Merge artifacts and flow accumulation

Merge artifacts and flow accumulation

I've been struggling with this problem for awhile. Here is a curvature raster to illustrate the problem">

Wondering if the issue could be with rasters that are derived from elevations (curvature) rather than the original dem data. Some issue similar to hill shade rasters, which can be problematic to mosaic as mentioned here

'HILLSHADE NOTE: (Do not MOSAIC hillshades: MOSAIC the DEM's first and then create a hillshade). When working with multiple DEM files, it is important to MOSAIC the individual DEM files before creating a hillshade. A hillshade process cannot create any 'shading' at the edges of the dataset (there is nothing to compare the edge cells with). This will create data gaps if two hillshades are MOSAICed - even if the original DEM files did not have a gap… '

Fusion of high-resolution DEMs for water flow modeling

New technologies for terrain reconstruction have increased the availability of topographic data at a broad range of resolutions and spatial extents. The existing digital elevation models (DEMs) can now be updated at a low cost in selected study areas with newer, often higher resolution data using unmanned aerial systems (UAS) or terrestrial sensors. However, differences in spatial coverage and levels of detail often create discontinuities along the newly mapped area boundaries and subsequently lead to artifacts in results of DEM analyses or models of landscape processes.


To generate a seamless updated DEM, we propose a generalized approach to DEM fusion with a smooth transition while preserving important topographic features. The transition is controlled by distance-based weighted averaging along the DEMs’ blending overlap with spatially variable width based on elevation differences.


We demonstrate the method on two case studies exploring the effects of DEM fusion on water flow modeling in the context of precision agriculture. In the first case study, we update a lidar-based DEM with a fused set of two digital surface models (DSMs) derived from imagery acquired by UAS. In the second application, developed for a tangible geospatial interface, we fuse a georeferenced, physical sand model continuously scanned by a Kinect sensor with a lidar-based DEM of the surrounding watershed in order to computationally simulate and test methods for controlling storm water flow.


The results of our experiments demonstrate the importance of seamless, robust fusion for realistic simulation of water flow patterns using multiple high-resolution DEMs.

Nile River

The Nile River flows over 6,600 kilometers (4,100 miles) until emptying into the Mediterranean Sea. For thousands of years, the river has provided a source of irrigation to transform the dry area around it into lush agricultural land. Today, the river continues to serve as a source of irrigation, as well as an important transportation and trade route.

Anthropology, Sociology, Geography, Social Studies, Ancient Civilizations

Women and children on the banks of the nile

The Nile River has been a central feature of life in northeast Africa for thousands of years. Even today, families come to gather water from the riverbank, surrounded by ruins left by ancient civilizations.

Photograph by David Boyer

The Nile River flows from south to north through eastern Africa. It begins in the rivers that flow into Lake Victoria (located in modern-day Uganda, Tanzania, and Kenya), and empties into the Mediterranean Sea more than 6,600 kilometers (4,100 miles) to the north, making it one of the longest river in the world. The Nile River was critical to the development of ancient Egypt. In addition to Egypt, the Nile runs through or along the border of 10 other African countries, namely, Burundi, Tanzania, Rwanda, the Democratic Republic of the Congo, Kenya, Uganda, Sudan, Ethiopia, and South Sudan. Its three main tributaries are the White Nile, the Blue Nile, and the Atbara.

The soil of the Nile River delta between El Qâhira (Cairo) and the Mediterranean Sea is rich in nutrients, due to the large silt deposits the Nile leaves behind as it flows into the sea. The banks of the Nile all along its vast length contain rich soil as well, thanks to annual flooding that deposits silt. From space, the contrast between the Nile's lush green river banks and the barren desert through which it flows is obvious.

For millennia, much of Egypt's food has been cultivated in the Nile delta region. Ancient Egyptians developed irrigation methods to increase the amount of land they could use for crops and support a thriving population. Beans, cotton, wheat, and flax were important and abundant crops that could be easily stored and traded.

The Nile River delta was also an ideal growing location for the papyrus plant. Ancient Egyptians used the papyrus plant in many ways, such as making cloth, boxes, and rope, but by far its most important use was in making paper. Besides using the river's natural resources for themselves and trading them with others, early Egyptians also used the river for bathing, drinking, recreation, and transportation.

Today, 95 percent of Egyptians live within a few kilometers of the Nile. Canals bring water from the Nile to irrigate farms and support cities. The Nile supports agriculture and fishing. The Nile also has served as an important transportation route for thousands of years. Today, some residents of El Qâhira (Cairo) have begun using private speed boats, water taxis, or ferries to avoid crowded streets. Dams, such as the Aswân High Dam in Egypt, have been built to help to tame the river and provide a source of hydroelectric power.

However, the silt and sediment that used to flow north, enriching the soil and building the delta, is now building up behind the dam instead. Instead of growing in size through the soil deposits, the delta is now shrinking due to erosion along the Mediterranean Sea. In addition, routine annual flooding no longer occurs along parts of the Nile. These floods were necessary to flush and clean the water of human and agricultural waste. As a result, the water is becoming more polluted.

The Nile River also continues to be an important trade route, connecting Africa with markets in Europe and beyond.


Study area

The Ikkour watershed is located in the southwestern part of the Moroccan, Middle Atlas Mountain (Fig. 1), at 32°32′–32°40′N and 5°50′–5°58′W, and covered an area of 55 km 2 . It is characterized by a semi-arid climate with rains frequently grouped during a few days per month. Precipitations are characterized by irregular distribution, spread irregularly from October–November to April–May with predominance in December, and are almost non-existent in July and August. The mean annual rainfall in the Oum Er Rbia Basin is 666 mm. The temperature varies between 5 and 50 °C with an average value of 17.7 °C. The geology of the region is dominated by the Jurassic formations. These formations are mainly composed of limestone, dolomitic limestone, and marls underlying generally Permo-Triassic formations composed of red clays and doleritic basalts, and covered in places by Quaternary terraces. Soils and their evolution depend essentially on the nature of the lithological substrates, which under the influence of environmental factors (climate, vegetation, exhibition, topography…) gives birth to different soil types. The climate is of a continental type. This site is located in mountainous areas and is marked by a great irregularity in the amounts of precipitation and a regression of vegetation cover due to human action.

Location of the study area

The Oued Ikkour that is a tributary of the Oum Er Rbia River crosses a distance of 15 km before reaching the Zaouit Cheikh City. It is characterized by a steep slope of ≈10° on average, an elongated shape and an index of compactness of 1.25. The Ikkour watershed presents rugged terrain with the highest elevation of 2209 m. It is marked by a regression of forest cover due to agricultural extension, intensive pasture, and deforestation.

The soil erosion assessment depends upon the regional characteristics of the area, namely climate, soil condition, land use/land cover, topography, and lithology. To prepare maps of these characteristics, the data used in this study are collected from various sources. The Landsat 8 OLI image with a resolution of 30 m was downloaded from Earth Explorer dated June 21, 2015. It has been properly used for the spectral index method. The digital elevation model (DEM) of 30 m resolution of the study area was downloaded from ASTER GDEM. It was used to generate topographic parameters (slope, hydrographic network). The geological map (1:500,000) of Rabat was used to digitize geological formations. The monthly and annual rainfall data from 1985 to 2014 were obtained from the Hydraulic Basin Agency of Oum Er Rbia and Tadla-Azilal Regional Directorate of Water and Forests. The topsoil samples were collected over 22 locations within the study watershed in order to determine soil texture and organic matter content. The soil texture was determined by the Robinson pipette method, and the soil EC was determined from the suspension prepared by adding 50 ml de-ionized water to 10 g of sediment and shaking for 30 min. The topographic parameters of the watershed and the thematic factor maps were extracted using ArcGIS 10.2 software.

An icy ‘time machine’?

Since archaeologists started systematically surveying melting ice sites 15 years ago, ice patches from Norway to North America have yielded almost perfectly-preserved artifacts from long-ago time periods. In isolation, the individual finds contain information about craftsmanship and long-ago hunting traditions.

Langfonne, in fact, was one of the first ice patch sites to come to light, after a local hiker discovered a 3,300-year-old leather shoe sitting next to the edge of the ice patch in the summer of 2006 and reported it to archaeologist Lars Pilø, now a researcher at the Innlandet County Council Cultural Heritage Department and a co-author of the new study.

Ever since that discovery alerted Pilø to the possibility of artifacts preserved in mountain ice patches, researchers in Norway and beyond—there are similar sites in Canada’s Yukon, the Rockies in the U.S. and the Alps in Europe—have wondered if the distribution of objects on and around the ice might tell them about how and when the ice patch sites were used and how they grew over time.

Unlike glaciers, which are essentially slow-moving frozen rivers, ice patches are fixed deposits of snow and ice that may grow and shrink over time. Sites like Langfonne, researchers assumed, resemble a patch of snow at the end of winter: As temperatures increase, artifacts trapped inside melt out in the order they were deposited.

“The idea was, ice is like a time machine. Anything that lands on it stays there and is protected,” Pilø says.

That meant the oldest items would be found in the deepest core of the ice patch, in the same way that archaeologists working with artifacts buried in soil assume lower layers of dirt contain older artifacts. And because the ice patches were thought to grow steadily with each winter’s snowfall, more recent finds would be closer to the edges of the patch.

If ice patches froze artifacts exactly where they were lost, archaeologists theorized, those items could help reconstruct what people did there in the past, how big the ice patches were at specific points in prehistory, and how fast they grew and shrank over time.

The Langfonne arrows seemed like a way to test the time-machine theory.

The arrows and reindeer bones confirmed earlier suspicions that Norway’s high mountain ice patches were reindeer-hunting hotspots: When the cold-loving creatures retreated to the ice to avoid biting insects during the summer months, people followed with bows, arrows, and hunting knives.

But after radiocarbon dating all the arrows and gathering dozens more dates from reindeer remains they found on the ice, the researchers realized that, at Langfonne at least, the time-machine theory was unreliable. Researchers expected that the oldest items would be trapped in place from the day they were lost and preserved just as well as artifacts buried in the ice in later centuries. But the oldest artifacts at Langfonne, which date back to the Neolithic, were fragmented and heavily weathered, as though they’d been churned by the ice or exposed to sun and wind for years.

Arrows from later periods, like the 1,500-year-old arrow that used a sharpened mussel shell harvested from a river at least 50 miles away, looked as though they were shot just yesterday. “That raises the suspicion something happened inside the ice” that exposed and re-froze the older items, Pilø says.

And the arrows didn’t seem to be emerging in any particular order, as you’d expect if the ice formed perfect layers over time. Arrows made thousands of years apart were lying not far from each other along the ice edge. “The idea that you find the oldest evidence when the ice patch is at its smallest—that isn’t really true,” says Montana State Parks archaeologist Rachel Reckin, who was not part of the research team. “It looks like gravity and water are moving artifacts down a great deal.”

Co-author Atle Nesje, a glaciologist at the University of Bergen, says that thousands of years ago, warm summers probably exposed older artifacts, which were carried to the edge of the ice patch by streams of meltwater before freezing again. The weight of ice pressing down on lower layers might have caused them to shift, carrying their frozen contents with them. Or lightweight wooden arrow shafts might have been blown across the surface by fierce winds before getting lodged in rocks or getting covered again by snow. Arrows lost in the snow more recently, meanwhile, might have stayed in place.

Because old arrows might be washed down by meltwater and then re-freeze, the spot where they were found could be a long way from where they originally landed. That meant using radiocarbon dated arrows to map the size of the ice patch in the past was a dead end. “Glaciologists and ice patch archaeologists were hoping that artifacts could give us an idea of the size over time, but that’s not the case,” Reckin says.

The specter of chaos

Cultural heritage experts may be divided over the Taliban’s sincerity, but they agree that chaos, rather than an Islamist takeover, poses the greater danger.

“Our fears are less about a possible threat posed by the Taliban than the prospect of a breakdown in law and order,” said Jolyon Leslie, a preservationist currently working to shore up an ancient Buddhist stupa outside Kabul. He has worked to involve local communities that are better placed to protect such monuments.

Hewadwall argues that chaos already prevails, particularly in rural regions. A lack of security and constantly shifting alliances have enabled looters—whether poverty-stricken villagers, roving gangs, Taliban, or various militia—to pilfer artifacts that then are smuggled to art market hubs like Dubai. Buddhist sites, often packed with highly valuable statues, have been particularly hard hit. (See 20 of the world’s most beautiful Buddhist temples.)

Despite fears of a Taliban-dominated regime, the United States last month returned to Afghanistan over 33 artifacts worth an estimated $1.8 million. The objects had been stolen in the past decade and were part of an extensive collection owned by a New York art dealer.

“These recovered works are irreplaceable pieces of Afghanistan’s diverse culture and rich history,” said Afghan Ambassador Roya Rahmani at the repatriation ceremony in New York. “It is my greatest honor to help facilitate their return home.”

Neighborhood Operations

Tobler’s first law of geography states that “everything is related to everything else, but near things are more related than distant things.” Neighborhood operations Operations performed on a central, target cell and surrounding cells. represent a group of frequently used spatial analysis techniques that rely heavily on this concept. Neighborhood functions examine the relationship of an object with similar surrounding objects. They can be performed on point, line, or polygon vector datasets as well as on raster datasets. In the case of vector datasets, neighborhood analysis is most frequently used to perform basic searches. For example, given a point dataset containing the location of convenience stores, a GIS could be employed to determine the number of stores within 5 miles of a linear feature (i.e., Interstate 10 in California).

Neighborhood analyses are often more sophisticated when used with raster datasets. Raster analyses employ moving windows, also called filters or kernels, to calculate new cell values for every location throughout the raster layer’s extent. These moving windows can take many different forms depending on the type of output desired and the phenomena being examined. For example, a rectangular, 3-by-3 moving window is commonly used to calculate the mean, standard deviation, sum, minimum, maximum, or range of values immediately surrounding a given “target” cell (Figure 8.6 "Common Neighborhood Types around Target Cell “x”: (a) 3 by 3, (b) Circle, (c) Annulus, (d) Wedge"). The target cell Cell found in the center of the 3-by-3 moving window. is that cell found in the center of the 3-by-3 moving window. The moving window passes over every cell in the raster. As it passes each central target cell, the nine values in the 3-by-3 window are used to calculate a new value for that target cell. This new value is placed in the identical location in the output raster. If one wanted to examine a larger sphere of influence around the target cells, the moving window could be expanded to 5 by 5, 7 by 7, and so forth. Additionally, the moving window need not be a simple rectangle. Other shapes used to calculate neighborhood statistics include the annulus, wedge, and circle (Figure 8.6 "Common Neighborhood Types around Target Cell “x”: (a) 3 by 3, (b) Circle, (c) Annulus, (d) Wedge").

Figure 8.6 Common Neighborhood Types around Target Cell “x”: (a) 3 by 3, (b) Circle, (c) Annulus, (d) Wedge

Neighborhood operations are commonly used for data simplification on raster datasets. An analysis that averages neighborhood values would result in a smoothed output raster with dampened highs and lows as the influence of the outlying data values are reduced by the averaging process. Alternatively, neighborhood analyses can be used to exaggerate differences in a dataset. Edge enhancement is a type of neighborhood analysis that examines the range of values in the moving window. A large range value would indicate that an edge occurs within the extent of the window, while a small range indicates the lack of an edge.


The Age of Exploration generally refers to the period between the 15th and 17th centuries. During this time, technological advances in shipbuilding and navigation made it easier for nations to explore outside previous boundaries. Globalization has had many benefits, for example, new products to Europeans were discovered, such as tea, silk and sugar when Europeans developed new trade routes around Africa to India and the Spice Islands, Asia, and eventually running to the Americas.

In addition to trading in goods, many nations began to trade in slavery. Trading in slaves was another way by which diseases were carried to new locations and peoples, for instance, from sub-Saharan Africa to the Caribbean and the Americas. During this time, different societies began to integrate, increasing the concentration of humans and animals in certain places, which led to the emergence of new diseases as some jumped in mutation from animals to humans.

During this time sorcerers' and witch doctors' treatment of disease was often focused on magic and religion, and healing the entire body and soul, rather than focusing on a few symptoms like modern medicine. Early medicine often included the use of herbs and meditation. Based on archaeological evidence, some prehistoric practitioners in both Europe and South America used trephining, making a hole in the skull to release illness. [4] Severe diseases were often thought of as supernatural or magical. The result of the introduction of Eurasian diseases to the Americas was that many more native peoples were killed by disease and germs than by the colonists' use of guns or other weapons. Scholars estimate that over a period of four centuries, epidemic diseases wiped out as much as 90 percent of the American indigenous populations. [3]

In Europe during the age of exploration, diseases such as smallpox, measles and tuberculosis (TB) had already been introduced centuries before through trade with Asia and Africa. People had developed some antibodies to these and other diseases from the Eurasian continent. When the Europeans traveled to new lands, they carried these diseases with them. (Note: Scholars believe TB was already endemic in the Americas.) When such diseases were introduced for the first time to new populations of humans, the effects on the native populations were widespread and deadly. The Columbian Exchange, referring to Christopher Columbus's first contact with the native peoples of the Caribbean, began the trade of animals, and plants, and unwittingly began an exchange of diseases. [3]

It was not until the 1800s that humans began to recognize the existence and role of germs and microbes in relation to disease. Although many thinkers had ideas about germs, it was not until French doctor Louis Pasteur spread his theory about germs, and the need for washing hands and maintaining sanitation (particularly in medical practice), that anyone listened. Many people were quite skeptical, but on May 22, 1881 Pasteur persuasively demonstrated the validity of his germ theory of disease with an early example of vaccination. The anthrax vaccine was administered to 25 sheep while another 25 were used as a control. On May 31, 1881 all of the sheep were exposed to anthrax. While every sheep in the control group died, each of the vaccinated sheep survived. [5] Pasteur's experiment would become a milestone in disease prevention. His findings, in conjunction with other vaccines that followed, changed the way globalization affected the world.

Effects of globalization on disease in the modern world Edit

Modern modes of transportation allow more people and products to travel around the world at a faster pace they also open the airways to the transcontinental movement of infectious disease vectors. [6] One example is the West Nile virus. It is believed that this disease reached the United States via “mosquitoes that crossed the ocean by riding in airplane wheel wells and arrived in New York City in 1999.” [6] With the use of air travel, people are able to go to foreign lands, contract a disease and not have any symptoms of illness until after they get home, and having exposed others to the disease along the way. Another example of the potency of modern modes of transportation in increasing the spread of disease is the 1918 Spanish Flu pandemic. Global transportation, back in the early 20th century, was able to spread a virus because the network of transmittance and trade was already global. The virus was found on crew members of ships and trains, and all the infected employees spread the virus everywhere they traveled. [7] As a result, almost 50-100 million people died of this global transmission. [7]

As medicine has progressed, many vaccines and cures have been developed for some of the worst diseases (plague, syphilis, typhus, cholera, malaria) which people suffer. But, because the evolution of disease organisms is very rapid, even with vaccines, there is difficulty providing full immunity to many diseases. Since vaccines are made partly from the virus itself, when an unknown virus is introduced into the environment, it takes time for the medical community to formulate a curable vaccine. [8] The lack of operational and functional research and data, which provide a quicker and more strategized pathway to a reliable vaccine, makes for a lengthy vaccine development timeline. Even though frameworks are set up and preparations plans are utilized to decrease the COVID-19 cases, a vaccine is the only way to ensure complete immunization. Some systems like the IIS, Immunization Information System, help give preliminary structure for quick responses to outbreaks and unknown viruses. [9] These systems employ past data and research-based on modern world vaccine development successes. [9] Finding vaccines at all for some diseases remains extremely difficult. Without vaccines, the global world remains vulnerable to infectious diseases.

Evolution of disease presents a major threat in modern times. For example, the current "swine flu" or H1N1 virus is a new strain of an old form of flu, known for centuries as Asian flu based on its origin on that continent. From 1918 to 1920, a post-World War I global influenza epidemic killed an estimated 50–100 million people, including half a million in the United States alone. [10] H1N1 is a virus that has evolved from and partially combined with portions of avian, swine, and human flu. [11]

Globalization has increased the spread of infectious diseases from South to North, but also the risk of non-communicable diseases by transmission of culture and behavior from North to South. It is important to target and reduce the spread of infectious diseases in developing countries. However, addressing the risk factors of non-communicable diseases and lifestyle risks in the South that cause disease, such as use or consumption of tobacco, alcohol, and unhealthy foods, is important as well. [12]

Even during pandemics, it is vital to recognize economic globalization in being a catalyst in the spread of the coronavirus. Economic factors are especially damaged by increased global lockdown regulations and trade blockades. As transportation globalized, economies expanded. Internalized economies saw great financial opportunities in global trade. [13] With increased interconnectivity among economies and the globalization of the world economy, the spread of the coronavirus maximized the potentiality of global recessions. The coronavirus pandemic caused many economic disruptions, which caused a functional disconnect in the supply chain and the flow of goods. As transportation modes are relevant to the spread of infectious diseases, it is important to also recognize the economy being the motor of this globalized transmission system. [13]

Plague Edit

Bubonic plague is a variant of the deadly flea-borne disease plague, which is caused by the enterobacteria Yersinia pestis, that devastated human populations beginning in the 14th century. Bubonic plague is primarily spread by fleas that lived on the black rat, an animal that originated in south Asia and spread to Europe by the 6th century. It became common to cities and villages, traveling by ship with explorers. A human would become infected after being bitten by an infected flea. The first sign of an infection of bubonic plague is swelling of the lymph nodes, and the formation of buboes. These buboes would first appear in the groin or armpit area, and would often ooze pus or blood. Eventually infected individuals would become covered with dark splotches caused by bleeding under the skin. The symptoms would be accompanied by a high fever, and within four to seven days of infection, more than half the victims would die.

The first recorded outbreak of plague occurred in China in the 1330s, a time when China was engaged in substantial trade with western Asia and Europe. The plague reached Europe in October 1347. It was thought to have been brought into Europe through the port of Messina, Sicily, by a fleet of Genoese trading ships from Kaffa, a seaport on the Crimean peninsula. When the ship left port in Kaffa, many of the inhabitants of the town were dying, and the crew was in a hurry to leave. By the time the fleet reached Messina, all the crew were either dead or dying the rats that took passage with the ship slipped unnoticed to shore and carried the disease with them and their fleas.

Within Europe, the plague struck port cities first, then followed people along both sea and land trade routes. It raged through Italy into France and the British Isles. It was carried over the Alps into Switzerland, and eastward into Hungary and Russia. For a time during the 14th and 15th centuries, the plague would recede. Every ten to twenty years, it would return. Later epidemics, however, were never as widespread as the earlier outbreaks, when 60% of the population died.

The third plague pandemic emerged in Yunnan province of China in the mid-nineteenth century. It spread east and south through China, reaching Guangzhou (Canton) and Hong Kong in 1894, where it entered the global maritime trade routes. Plague reached Singapore and Bombay in 1896. China lost an estimated 2 million people between plague's reappearance in the mid-nineteenth century and its retreat in the mid-twentieth. In India, between 1896 and the 1920s, plague claimed an estimated 12 million lives, most in the Bombay province. Plague spread into the countries around the Indian Ocean, the Red Sea and the Mediterranean. From China it also spread eastward to Japan, the Philippines and Hawaii, and in Central Asia it spread overland into the Russian territories from Siberia to Turkistan. By 1901 there had been outbreaks of plague on every continent, and new plague reservoirs would produce regular outbreaks over the ensuing decades. [14] [15]

Measles Edit

Measles is a highly contagious airborne virus spread by contact with infected oral and nasal fluids. When a person with measles coughs or sneezes, he releases microscopic particles into the air. During the 4- to 12-day incubation period, an infected individual shows no symptoms, but as the disease progresses, the following symptoms appear: runny nose, cough, red eyes, extremely high fever and a rash.

Measles is an endemic disease, meaning that it has been continually present in a community, and many people developed resistance. In populations that have not been exposed to measles, exposure to the new disease can be devastating. In 1529, a measles outbreak in Cuba killed two-thirds of the natives who had previously survived smallpox. Two years later measles was responsible for the deaths of half the indigenous population of Honduras, and ravaged Mexico, Central America, and the Inca civilization. [ citation needed ]

Historically, measles was very prevalent throughout the world, as it is highly contagious. According to the National Immunization Program, 90% of people were infected with measles by age 15, acquiring immunity to further outbreaks. Until a vaccine was developed in 1963, measles was considered to be deadlier than smallpox. [16] Vaccination reduced the number of reported occurrences by 98%. Major epidemics have predominantly occurred in unvaccinated populations, particularly among nonwhite Hispanic and African American children under 5 years old. [16] In 2000 a group of experts determined that measles was no longer endemic in the United States. The majority of cases that occur are among immigrants from other countries.

Typhus Edit

Typhus is caused by rickettsia, which is transmitted to humans through lice. The main vector for typhus is the rat flea. Flea bites and infected flea feaces in the respiratory tract are the two most common methods of transmission. In areas where rats are not common, typhus may also be transmitted through cat and opossum fleas. [17] The incubation period of typhus is 7–14 days. The symptoms start with a fever, then headache, rash, and eventually stupor. Spontaneous recovery occurs in 80–90% of victims.

The first outbreak of typhus was recorded in 1489. Historians believe that troops from the Balkans, hired by the Spanish army, brought it to Spain with them. [3] By 1490 typhus traveled from the eastern Mediterranean into Spain and Italy, and by 1494, it had swept across Europe. From 1500 to 1914, more soldiers were killed by typhus than from all the combined military actions during that time. It was a disease associated with the crowded conditions of urban poverty and refugees as well. Finally, during World War I, governments instituted preventative delousing measures among the armed forces and other groups, and the disease began to decline. [18] The creation of antibiotics has allowed disease to be controlled within two days of taking a 200 mg dose of tetracycline.

Syphilis Edit

Syphilis is a sexually transmitted disease that causes open sores, delirium and rotting skin, and is characterized by genital ulcers. Syphilis can also do damage to the nervous system, brain and heart. The disease can be transmitted from mother to child.

The origins of syphilis are unknown, and some historians argue that it descended from a twenty-thousand-year-old African zoonosis. Other historians place its emergence in the New World, arguing that the crews of Columbus's ships first brought the disease to Europe. [3] The first recorded case of syphilis occurred in Naples in 1495, after King Charles VIII of France besieged the city of Naples, Italy. The soldiers, and the prostitutes who followed their camps, came from all corners of Europe. When they went home, they took the disease with them and spread it across the continent. [3]

Smallpox Edit

Smallpox is a highly contagious disease caused by the Variola virus. There are four variations of smallpox variola major, variola minor, haemorrhagic, and malignant, with the most common being variola major and variola minor. Symptoms of the disease including hemorrhaging, blindness, back ache, vomiting, which generally occur shortly after the 12- to 17-day incubation period. The virus begins to attack skin cells, and eventually leads to an eruption of pimples that cover the whole body. As the disease progresses, the pimples fill up with pus or merge. This merging results in a sheet that can detach the bottom layer from the top layer of skin. The disease is easily transmitted through airborne pathways (coughing, sneezing, and breathing), as well as through contaminated bedding, clothing or other fabrics,

It is believed that smallpox first emerged over 3000 years ago, probably in India or Egypt. There have been numerous recorded devastating epidemics throughout the world, with high losses of life.

Smallpox was a common disease in Eurasia in the 15th century, and was spread by explorers and invaders. After Columbus landed on the island of Hispaniola during his second voyage in 1493, local people started to die of a virulent infection. Before the smallpox epidemic started, more than one million indigenous people had lived on the island afterward, only ten thousand had survived. [3]

During the 16th century, Spanish soldiers introduced smallpox by contact with natives of the Aztec capital Tenochtitlan. A devastating epidemic broke out among the indigenous people, killing thousands. [19]

In 1617, smallpox reached Massachusetts, probably brought by earlier explorers to Nova Scotia, Canada.” [3] By 1638 the disease had broken out among people in Boston, Massachusetts. In 1721 people fled the city after an outbreak, but the residents spread the disease to others throughout the thirteen colonies. Smallpox broke out in six separate epidemics in the United States through 1968.

The smallpox vaccine was developed in 1798 by Edward Jenner. By 1979 the disease had been completely eradicated, with no new outbreaks. The WHO stopped providing vaccinations and by 1986, vaccination was no longer necessary to anyone in the world except in the event of future outbreak.

Leprosy Edit

Leprosy, also known as Hansen's Disease, is caused by a bacillus, Mycobacterium leprae. It is a chronic disease with an incubation period of up to five years. Symptoms often include irritation or erosion of the skin, and effects on the peripheral nerves, mucosa of the upper respiratory tract and eyes. The most common sign of leprosy are pale reddish spots on the skin that lack sensation.

Leprosy originated in India, more than four thousand years ago. It was prevalent in ancient societies in China, Egypt and India, and was transmitted throughout the world by various traveling groups, including Roman Legionnaires, Crusaders, Spanish conquistadors, Asian seafarers, European colonists, and Arab, African, and American slave traders. Some historians believe that Alexander the Great's troops brought leprosy from India to Europe during the 3rd century BC. [20] With the help of the crusaders and other travelers, leprosy reached epidemic proportions by the 13th century.

Once detected, leprosy can be cured using multi-drug therapy, composed of two or three antibiotics, depending on the type of leprosy. In 1991 the World Health Assembly began an attempt to eliminate leprosy. By 2005 116 of 122 countries were reported to be free of leprosy. [21]

Malaria Edit

On Nov. 6, 1880 Alphonse Laveran discovered that malaria (then called "Marsh Fever") was a protozoan parasite, and that mosquitoes carry and transmit malaria. [22] Malaria is a protozoan infectious disease that is generally transmitted to humans by mosquitoes between dusk and dawn. The European variety, known as "vivax" after the Plasmodium vivax parasite, causes a relatively mild, yet chronically aggravating disease. The west African variety is caused by the sporozoan parasite, Plasmodium falciparum, and results in a severely debilitating and deadly disease.

Malaria was common in parts of the world where it has now disappeared, as the vast majority of Europe (disease of African descent are particularly diffused in the Empire romain) and North America . In some parts of England, mortality due to malaria was comparable to that of sub-Saharan Africa today. Although William Shakespeare was born at the beginning of a colder period called the "Little Ice Age", he knew enough ravages of this disease to include in eight parts. Plasmodium vivax lasted until 1958 in the polders of Belgium and the Netherlands. In the 1500s, it was the European settlers and their slaves who probably brought malaria on the American continent (we know that Columbus was suffering from this disease before his arrival in the new land). The Spanish Jesuit missionaries saw the Indians bordering on Lake Loxa Peru used the Cinchona bark powder to treat fevers. However, there is no reference to malaria in the medical literature of the Maya or Aztecs. The use of the bark of the "fever tree" was introduced into European medicine by Jesuit missionaries whose Barbabe Cobo who experimented in 1632 and also by exports, which contributed to the precious powder also being called "Jesuit powder". A study in 2012 of thousands of genetic markers for Plasmodium falciparum samples confirmed the African origin of the parasite in South America (Europeans themselves have been affected by this disease through Africa): it borrowed from the mid-sixteenth century and the mid-nineteenth the two main roads of the slave trade, the first leading to the north of South America (Colombia) by the Spanish, the second most leading south (Brazil) by Portugueses.

Parts of Third World countries are more affected by malaria than the rest of the world. For instance, many inhabitants of sub-Saharan Africa are affected by recurring attacks of malaria throughout their lives. [23] In many areas of Africa, there is limited running water. The residents' use of wells and cisterns provides many sites for the breeding of mosquitoes and spread of the disease. Mosquitoes use areas of standing water like marshes, wetlands, and water drums to breed.

Tuberculosis Edit

The bacterium that causes tuberculosis, Mycobacterium tuberculosis, is generally spread when an infected person coughs and another person inhales the bacteria. Once inhaled TB frequently grows in the lungs, but can spread to any part of the body. Although TB is highly contagious, in most cases the human body is able to fend off the bacteria. But, TB can remain dormant in the body for years, and become active unexpectedly. If and when the disease does become active in the body, it can multiply rapidly, causing the person to develop many symptoms including cough (sometimes with blood), night sweats, fever, chest pains, loss of appetite and loss of weight. This disease can occur in both adults and children and is especially common among those with weak or undeveloped immune systems.

Tuberculosis (TB) has been one of history's greatest killers, taking the lives of over 3 million people annually. It has been called the "white plague". According to the WHO, approximately fifty percent of people infected with TB today live in Asia. It is the most prevalent, life-threatening infection among AIDS patients. It has increased in areas where HIV seroprevalence is high. [24]

Air travel and the other methods of travel which have made global interaction easier, have increased the spread of TB across different societies. Luckily, the BCG vaccine was developed, which prevents TB meningitis and miliary TB in childhood. But, the vaccine does not provide substantial protection against the more virulent forms of TB found among adults. Most forms of TB can be treated with antibiotics to kill the bacteria. The two antibiotics most commonly used are rifampicin and isoniazid. There are dangers, however, of a rise of antibiotic-resistant TB. The TB treatment regimen is lengthy, and difficult for poor and disorganized people to complete, increasing resistance of bacteria. [24] Antibiotic-resistant TB is also known as "multidrug-resistant tuberculosis." "Multidrug-resistant tuberculosis" is a pandemic that is on the rise. Patients with MDR-TB are mostly young adults who are not infected with HIV or have other existing illness. Due to the lack of health care infrastructure in underdeveloped countries, there is a debate as to whether treating MDR-TB will be cost effective or not. The reason is the high cost of "second-line" antituberculosis medications. It has been argued that the reason the cost of treating patients with MDR-TB is high is because there has been a shift in focus in the medical field, in particular the rise of AIDS, which is now the world's leading infectious cause of death. Nonetheless, it is still important to put in the effort to help and treat patients with "multidrug-resistant tuberculosis" in poor countries. [25]


HIV and AIDS are among the newest and deadliest diseases. According to the World Health Organization, it is unknown where the HIV virus originated, but it appeared to move from animals to humans. It may have been isolated within many groups throughout the world. It is believed that HIV arose from another, less harmful virus, that mutated and became more virulent. The first two AIDS/HIV cases were detected in 1981. As of 2013, an estimated 1.3 million persons in the United States were living with HIV or AIDS, [26] almost 110,000 in the UK [27] and an estimated 35 million people worldwide are living with HIV”. [28]

Despite efforts in numerous countries, awareness and prevention programs have not been effective enough to reduce the numbers of new HIV cases in many parts of the world, where it is associated with high mobility of men, poverty and sexual mores among certain populations. Uganda has had an effective program, however. Even in countries where the epidemic has a very high impact, such as Swaziland and South Africa, a large proportion of the population do not believe they are at risk of becoming infected. Even in countries such as the UK, there is no significant decline in certain at-risk communities. 2014 saw the greatest number of new diagnoses in gay men, the equivalent of nine being diagnosed a day. [29]

Initially, HIV prevention methods focused primarily on preventing the sexual transmission of HIV through behaviour change. The ABC Approach - "Abstinence, Be faithful, Use a Condom". However, by the mid-2000s, it became evident that effective HIV prevention requires more than that and that interventions need to take into account underlying socio-cultural, economic, political, legal and other contextual factors. [30]

Ebola Edit

The Ebola outbreak, which was the 26th outbreak since 1976, started in Guinea in March 2014. The WHO warned that the number of Ebola patients could rise to 20,000, and said that it used $489m (£294m) to contain Ebola within six to nine months. [31] The outbreak was accelerating. Medecins sans Frontieres has just opened a new Ebola hospital in Monrovia, and after one week it is already a capacity of 120 patients. It said that the number of patients seeking treatment at its new Monrovia centre was increasing faster than they could handle both in terms of the number of beds and the capacity of the staff, adding that it was struggling to cope with the caseload in the Liberian capital. Lindis Hurum, MSF's emergency coordinator in Monrovia, said that it was humanitarian emergency and they needed a full-scale humanitarian response. [31] Brice de la Vinge, MSF director of operations, said that it was not until five months after the declaration of the Ebola outbreak that serious discussions started about international leadership and coordination, and said that it was not acceptable.

Leptospirosis Edit

Leptospirosis, also known as the "rat fever" or "field fever" is an infection caused by Leptospira. Symptoms can range from none to mild such as headaches, muscle pains, and fevers to severe with bleeding from the lungs or meningitis. Leptospira is transmitted by both wild and domestic animals, most commonly by rodents. It is often transmitted by animal urine or by water or soil containing animal urine coming into contact with breaks in the skin, eyes, mouth, or nose. [32] The countries with the highest reported incidence are located in the Asia-Pacific region (Seychelles, India, Sri Lanka and Thailand) with incidence rates over 10 per 1000,000 people s well as in Latin America and the Caribbean (Trinidad and Tobago, Barbados, Jamaica, El Salvador, Uruguay, Cuba, Nicaragua and Costa Rica) [33] However, the rise in global travel and eco-tourism [34] has led to dramatic changes in the epidemiology of leptospirosis, and travelers from around the world have become exposed to the threat of leptospirosis. Despite decreasing prevalence of leptospirosis in endemic regions, previously non-endemic countries are now reporting increasing numbers of cases due to recreational exposure [35] International travelers engaged in adventure sports are directly exposed to numerous infectious agents in the environment and now comprise a growing proportion of cases worldwide. [36]

Disease X Edit

The World Health Organization (WHO) proposed the name Disease X in 2018 to focus on preparations and predictions of a major pandemic. [37]

COVID-19 (SARS-CoV-2) worldwide crisis Edit

The virus outbreak originated in Wuhan, China. [38] It was first detected back in December 2019, which is why scientists called it COVID-19 (coronavirus disease 2019). [39] This outbreak has since caused a health issue in the city of Wuhan, China which evolved into a global pandemic. The World Health Organization officially declared it a pandemic back on March 11, 2020. [40]

As of May 2020, scientists believe that the coronavirus, a zoonotic disease, is linked to the wet markets in China. [41] Epidemiologists have also warned of the virus's contagiousness. Specialists have declared that the spread of SARS-Cov-2 is still unknown. The generally accepted notion among virologists and experts is that the action of inhaling droplets from an infected person is most likely the way SARS-Cov-2 is spreading. [42] As more people travel and more goods and capital are traded globally, COVID-19 cases started to slowly appear all over the world.

Some of the symptoms that COVID-19 patients could experience is shortness of breath (which might be a sign of pneumonia), cough, fever, and diarrhea. [43] The three most recorded and common symptoms are fever, tiredness, and coughing, as reported by the World Health Organization. [43] COVID-19 is also categorized among the viruses that can show no symptoms in the carrier. Asymptomatic COVID-19 carriers transmitted the virus to many people which eventually did show symptoms, some being deadly. [43]

The first number of cases was detected in Wuhan, China, the origin of the outbreak. [44] On December 31, 2019, Wuhan Municipal Health Commission announced to the World Health Organization that the number of pneumonia cases that have been previously detected in Wuhan, Hubei Province is now under investigation. [44] Proper identification of a novel coronavirus was developed and reported, making the pneumonia cases in China the first reported cases of COVID-19. [44] As of June 18, 2020, there are around 8.58 million confirmed COVID-19 cases around the world. [45] Confirmed deaths as a result of COVID-19 is just under 460,000 globally. [45] Almost 4.5 million of the 8.58 million confirmed COVID-19 cases have successfully recovered. [45] Countries showing lack of preparation and awareness back in January and February 2020 are now reporting the highest numbers of COVID-19 cases. The United States leads the worldwide count with almost 2.26 million confirmed cases. [45] Deaths in The United States have just crossed 120,000, the highest death count in any country to date. [45] Brazil, Russia, Spain, UK, and Italy have all suffered because of the increase in cases, leading to a crippled health system unable to attend to so many sick people at one time.

The first-ever confirmed case of COVID-19 in the United States was in Washington State back on January 21, 2020. [46] It was a man who had just returned from China. Following this incident, on January 31, 2020, Trump announced that travel to and from China is restricted, effective on February 2, 2020. [46] On March 11, 2020, Trump issues executive order to restrict travel from Europe, except for the UK and Ireland. [46] On May 24, 2020, Trump bans travel from Brazil, as Brazil becomes the new center of the coronavirus pandemic. [46] International restrictions were set to decrease international entities of entering a country, potentially carrying the virus. This is because governments understand that with the accessibility in travel and free trade, any person can travel and carry the virus to a new environment. Recommendations to U.S. travelers have been set by the State Department. As of March 19, 2020, some countries have been marked Level 4 “do not travel”. [47] The coronavirus pandemic travel restrictions have affected almost 93% of the global population. [47] Increased travel restrictions effectively aid multilateral and bilateral health organizations to control the number of confirmed cases of COVID-19.

Globalization can benefit people with non-communicable diseases such as heart problems or mental health problems. Global trade and rules set forth by the World Trade Organization can actually benefit the health of people by making their incomes higher, allowing them to afford better health care. While it has to be admitted making many non-communicable diseases more likely as well. Also the national income of a country, mostly obtained by trading on the global market, is important because it dictates how much a government spends on health care for its citizens. It also has to be acknowledged that an expansion in the definition of disease often accompanies development, so the net effect is not clearly beneficial due to this and other effects of increased affluence. Metabolic syndrome is one obvious example. Although poorer countries have not yet experienced this and are still suffering from diseases listed above. [48]

Globalization is multifaceted in implementation and is objective in the framework and systemic ideology. Infectious diseases spread mainly as a result of the modern globalization of many and almost all industries and sectors. Economic globalization is the interconnectivity of world economies and the interdependency of internal and external supply chains. [49] With the advancement of science and technology, the possibility of economic globalization is enabled even more. Economic factors have been defined by global boundaries rather than national. The cost of activities of economic measures has been significantly decreased as a result of the advancements in the fields of technology and science, slowly creating an interconnected economy lacking centralized integration. [49] As economies increase levels of integration and singularity within the partnership, any global financial and economic disruptions would cause a global recession. [50] Collateral damage is further observed with the increase in integrated economic activity. Countries lean more on economic benefits than health benefits, which lead to a miscalculated and ill-reported health issue.

A dying tradition

In an attempt to understand how and why the practice died out, archaeologist Emma Brownlee, a research fellow at the University of Cambridge’s Girton College who specializes in early medieval burial practices, dug into archaeological records that document more than 33,000 early medieval graves. Her analysis, recently published in the journal Antiquity, covered 237 cemeteries in northwestern Europe, the majority of them in England.

Using descriptions and drawings of tens of thousands of graves excavated over the past 60 years, Brownlee painstakingly calculated the average number of objects per grave, down to the last bead. She also gathered other important information, such as how long the cemeteries were in use, and what the most reliable dating techniques suggested about their age.

Then the number crunching began. Her map shows England abandoning grave goods as early as the mid-sixth century. By the time the Anglo-Saxon warrior was interred around 625, furnished burials were well on their way to abandonment.

“After the seventh century, nobody is being buried with things in their graves,” says Brownlee.

Since her data skews toward England, Brownlee cautions that English people didn’t necessarily lead the way. Nonetheless, her data shows that England finished its turn toward simpler burials by the 720s, while the rest of northwestern Europe took another half-century to follow suit.

Evaluation of Microalgae Biofuel Production Potential and Cultivation Sites Using Geographic Information Systems: A Review

Geographic Information System (GIS) tools have been used to strategically locate bioenergy facilities and optimize the relationship between biomass supply and demand, aiming to minimize overall fuel production costs. Microalgae, also termed third generation bioenergy feedstocks, are discussed for their potential to meet future energy demands. This study reviews literature on GIS applications to locate algae cultivation sites and estimate algae biofuel potential. To highlight the diversity of results, a quantitative comparison for the US studies is presented. We found two major assumptions that primarily limited the algae biofuel production potential estimates: (1) the production technology (open pond or photobioreactor), and (2) the number and type of resources considered, such as land type, CO2, water source, water quality, etc. All studies used binary (a location is either unsuitable or suitable) suitability models to determine areas for algae production. Most studies considered water, land, and CO2 resources, while some also accounted for infrastructure, soil properties, and work force requirements. We found that potential cultivation area in the USA is most sensitive to the constraints of CO2 availability and land cost. This review explains the wide range of algal biofuel potential estimates (from 0.09 to over 600 billion L yr −1 ) by identifying underlying assumptions, methodologies, and data. The highly variable outputs indicate the need for a comprehensive analysis of different criteria individually and in combination to estimate realistic biofuel potential. The results suggest that with models becoming increasingly detailed in considering resources and conversion/production technologies, further decrease in estimated theoretical production potential is expected under available technology.

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