Viet Nguyen (, February 25, 1981 – October 6, 2007) and Duc Nguyen (, born February 25, 1981) were a pair of conjoined twins born in Vietnam and surgically separated in 1988. Viet died in 2007 of natural causes.

Viet and Duc were born on February 25, 1981, in Kon Tum Province, Tây Nguyên, Vietnam. Viet was the elder and Duc was the younger of the two brothers. Their relatives claim that "the reason they became conjoined twins is the influence of Agent Orange that the U.S. military used as a defoliant during the Vietnam War". His mother was farming in the area doused with Agent Orange a year after the Vietnam War had ended. She also drank water from a well in that area. After that, Viet and Duc were born. On October 4, 1988, Viet and Duc were separated in the hospital in Ho Chi Minh City with the help of the Japanese Red Cross after Viet went into a coma.

Duc first entered junior high school, then dropped out and learned computer programming in a school. Now, he works at a hospital in Ho Chi Minh City. On December 16, 2006, he married Nguyen Thanh Tuyen in Ho Chi Minh City.

Viet's health problems continued after the separation, and he died due to liver failure and pneumonia on October 6, 2007, at the age of 26.

In Chinese alchemy, elixir poisoning refers to the toxic effects from elixirs of immortality that contained metals and minerals such as mercury and arsenic. The official "Twenty-Four Histories" record numerous Chinese emperors, nobles, and officials who ironically died from taking elixirs in order to prolong their lifespans. The first emperor to die from elixir poisoning was likely Qin Shi Huang (d. 210 BCE) and the last was Yongzheng (d. 1735). Despite common knowledge that immortality potions could be deadly, fangshi and Daoist alchemists continued the elixir-making practice for two millennia.

The distinction between Hua () and Yi (), also known as Sino–barbarian dichotomy, is an ancient Chinese concept that differentiated a culturally defined "China" (called Hua, Huaxia 華夏, or Xia 夏) from cultural or ethnic outsiders (Yi "barbarians"). Although Yi is often translated as "barbarian", other translations of this term in English include "foreigners",

"ordinary others" "wild tribes", and "uncivilized tribes."

The Hua–Yi distinction asserted Chinese superiority, but implied that outsiders could become "Hua" by adopting Chinese values and customs.

The etymology of English elixir derives from Medieval Latin "", from Arabic ("al-ʾiksīr"), probably from Ancient Greek ("xḗrion" "a desiccative powder for wounds"). "Elixir" originated in medieval European alchemy meaning "A preparation by the use of which it was sought to change metals into gold" (elixir stone or philosopher's stone) or "A supposed drug or essence with the property of indefinitely prolonging life" (elixir of life). The word was figuratively extended to mean "A sovereign remedy for disease. Hence adopted as a name for quack medicines" (e.g., Daffy's Elixir) and "The quintessence or soul of a thing; its kernel or secret principle". In modern usage, "elixir" is a pharmaceutical term for "A sweetened aromatic solution of alcohol and water, serving as a vehicle for medicine" ("Oxford English Dictionary", 2nd ed., 2009). Outside of Chinese cultural contexts, English "elixir poisoning" usually refers to accidental contamination, such as the 1937 Elixir sulfanilamide mass poisoning in the United States.

"Dān" 丹 "cinnabar; vermillion; elixir; alchemy" is the keyword for Chinese immortality elixirs. The red mineral cinnabar ("dānshā" 丹砂 lit. "cinnabar sand") was anciently used to produce the pigment vermilion ("zhūhóng" 朱紅) and the element mercury ("shuǐyín" 水銀 "watery silver" or "gǒng" 汞).

According to the "ABC Etymological Dictionary of Old Chinese", the etymology of Modern Standard Chinese "dān" from Old Chinese "*tān" (< *"tlan" ?) 丹 "red; vermillion; cinnabar", "gān" 矸 in "dāngān" 丹矸 from *"tân-kân" (< *"tlan-klan" ?) "cinnabar; vermillion ore", and "zhān" from *"tan" 旃 "a red flag" derive from Proto-Kam-Sui *"h-lan" "red" or Proto-Sino-Tibetan *"tja-n" or *"tya-n" "red". The *"t-" initial and *"t-" or *"k-" doublets indicate that Old Chinese borrowed this item. (Schuessler 2007: 204).

Although the word "dan" 丹 "cinnabar; red" frequently occurs in oracle script from the late Shang Dynasty (ca. 1600-1046 BCE) and bronzeware script and seal script from the Zhou Dynasty (1045-256 BCE), paleographers disagree about the graphic origins of the logograph 丹 and its ancient variants 𠁿 and 𠕑. Early scripts combine a 丶 dot or ⼀ stroke (depicting a piece of cinnabar) in the middle of a surrounding frame, which is said to represent:

- "jǐng" 井 "well" represents the mine from which the cinnabar is taken" ("Shuowen Jiezi")

- "the crucible of the Taoist alchemists" (Léon Wieger )

- "the contents of a square receptacle" (Bernhard Karlgren)

- "placed in a tray or palette to be used as red pigment" (Wang Hongyuan 王宏源)

- "mineral powder on a stretched filter-cloth" (Needham and Lu).

Many Chinese elixir names are compounds of "dan", such as "jīndān" 金丹 (with "gold") meaning "golden elixir; elixir of immortality; potable gold" and "xiāndān" 仙丹 (with "Daoist immortal") "elixir of immortality; panacea", and "shéndān" 神丹 (with "spirit; god") "divine elixir". "Bùsǐ zhī yào" 不死之藥 "drug of deathlessness" was another early name for the elixir of immortality. Chinese alchemists would "liàndān" 煉丹 (with "smelt; refine") "concoct pills of immortality" using a "dāndǐng" 丹鼎 (with "tripod cooking vessel; cauldron") "furnace for concocting pills of immortality". In addition, the ancient Chinese believed that other substances provided longevity and immortality, notably the "língzhī" 靈芝 ""Ganoderma" mushroom".

The transformation from chemistry-based "waidan" 外丹 "external elixir/alchemy" to physiology-based "neidan" 內丹 "internal elixir/alchemy" gave new analogous meanings to old terms. The human body metaphorically becomes a "ding" "cauldron" in which the adept forges the Three Treasures (essence, life-force, and spirit) within the "jindan" Golden Elixir within the "dāntián" 丹田 (with "field") "lower part of the abdomen".

In early China, alchemists and pharmacists were one in the same. Traditional Chinese Medicine also used less concentrated cinnabar and mercury preparations, and "dan" means "pill; medicine" in general, for example, "dānfāng" 丹方 semantically changed from "prescription for elixir of immortality" to "medical prescription". "Dan" was lexicalized into medical terms such as " dānjì" 丹劑 "pill preparation" and "dānyào" 丹藥 "pill medicine".

The Chinese names for immortality elixirs have parallels in other cultures and languages, for example, Indo-Iranian "soma" or "haoma", Sanskrit "amrita", and Greek "ambrosia".

The medical condition of being overweight or obesity is defined as "abnormal or excessive fat accumulation that may impair health". It is measured through the Body Mass Index (BMI), defined as a person's weight, in kilograms, divided by the square of the person's height, in meters. If an individual has a BMI of 25–29, he or she is overweight. Having a BMI of 30 or more means an individual is obese. The greater the BMI, the greater the risk of chronic diseases as a result of obesity. These diseases include cardiovascular diseases, diabetes, musculoskeletal disorders, cancer, and premature death.

The causes of childhood obesity can be based on both a combination of individual choices and socio-environmental adaptions with genetic factors playing an important role also.

The MONICA Project, sponsored by the World Health Organization, discovered that 30% of the population in the Arab World is overweight or obese, including adolescents and adults. This percentage is smaller for North African countries than oil-producing countries, but is still a prevalent trend. The spread of the Western lifestyle, defined as "the intake of attractive energy dense food with undesirable composition, increased consumption of animal fats and sugars and reduced consumption of dietary fiber, along with a lack of sufficient physical activity", is one of the leading causes. Specifically in the Arabian Peninsula, "physical activity of the population has significantly diminished with the availability of housemaids, private cars, television, and sophisticated household appliances. In addition, the types of food and fat intake have changed...".

Other common factors, besides a sedentary lifestyle and unhealthy food choices, across the Arab world include urbanization, technology, and a cultural appreciation of female plumpness and the practice of "leblouh" ("fattening").

Poverty and disease are tied closely together, with each factor aiding the other. Many diseases that primarily affect the poor serve to also deepen poverty and worsen conditions. Poverty also significantly reduces people's capabilities making it more difficult to avoid poverty related diseases.

The majority of diseases and related mortality in poor countries is due to preventable, treatable diseases for which medicines and treatment regimes are readily available. Poverty is in many cases the single dominating factor in higher rates of prevalence of these diseases. Poor hygiene, ignorance in health-related education, non-availability of safe drinking water, inadequate nutrition and indoor pollution are factors exacerbated by poverty.

Just the big three PRDs — TB, AIDS/HIV and Malaria — account for 18% of diseases in poor countries. The disease burden of treatable childhood diseases in high-mortality, poor countries is 5.2% in terms of disability-adjusted life years but just 0.2% in the case of advanced countries.

In addition, infant mortality and maternal mortality are far more prevalent among the poor. For example, 98% of the 11,600 daily maternal and neonatal deaths occur in developing countries.

Though heart disease is not exclusive to the poor, there are aspects of a life of poverty that contribute to its development. This category includes coronary heart disease, stroke and heart attack. Heart disease is the leading cause of death worldwide and there are disparities of morbidity between the rich and poor. Studies from around the world link heart disease to poverty. Low neighborhood income and education were associated with higher risk factors. Poor diet, lack of exercise and limited (or no) access to a specialist were all factors related to poverty, though to contribute to heart disease.

Both low income and low education were predictors of coronary heart disease, a subset of cardiovascular disease. Of those admitted to hospital in the United States for heart failure, women and African Americans were more likely to reside in lower income neighborhoods. In the developing world, there is a 10 fold increase in cardiac events in the black and urban populations.

Genetics, according to the Australian Health Survey plays a primary role in determining obesity. In 2011/2012 it was recorded that 90% of the Australian population had inherited their obese tendencies due to the epigenetic modifications of their mothers during pregnancy. Interchanging closely with the genetic factor, the environment and individual temptations are also highlighted as contributing causes to the worldwide epidemic. The genetic configuration influences the tendencies to become overweight, and diet and physical activity determines to what extent those tendencies are elaborated.

Islamophobia is an intense fear or hatred of, or prejudice against, the Islamic religion or Muslims, especially when seen as a geopolitical force or the source of terrorism.

The term was first used in the early 20th century and it emerged as a neologism in the 1970s, then it became increasingly salient during the 1980s and 1990s, and it reached public policy prominence with the report by the Runnymede Trust's Commission on British Muslims and Islamophobia (CBMI) entitled "Islamophobia: A Challenge for Us All" (1997). The introduction of the term was justified by the report's assessment that "anti-Muslim prejudice has grown so considerably and so rapidly in recent years that a new item in the vocabulary is needed".

The causes and characteristics of Islamophobia are still debated. Some commentators have posited an increase in Islamophobia resulting from the September 11 attacks, some from multiple terror attacks in Europe and the United States, while others have associated it with the increased presence of Muslims in the United States and in the European Union. Some people also question the validity of the term. The academics S. Sayyid and Abdoolkarim Vakil maintain that Islamophobia is a response to the emergence of a distinct Muslim public identity globally, the presence of Muslims is in itself not an indicator of the degree of Islamophobia in a society. Sayyid and Vakil maintain that there are societies where virtually no Muslims live but many institutionalized forms of Islamophobia still exist in them.

There is most likely a link between children's linear growth and household sanitation practices. The ingestion of high quantities of fecal bacteria by young children through putting soiled fingers or household items in the mouth leads to intestinal infections. This affect children's nutritional status by diminishing appetite, reducing nutrient absorption, and increasing nutrient losses.

The diseases recurrent diarrhoea and intestinal worm infections (helminthiasis) which are both linked to poor sanitation have been shown to contribute to child stunting. The evidence that a condition called environmental enteropathy also stunts children is not conclusively available yet, although the link is plausible and several studies are underway on this topic. Environmental enteropathy is a syndrome causing changes in the small intestine of persons and can be brought on due to lacking basic sanitary facilities and being exposed to faecal contamination on a long-term basis.

Research on a global level has found that the proportion of stunting that could be attributed to five or more episodes of diarrhoea before two years of age was 25%. Since diarrhoea is closely linked with water, sanitation and hygiene (WASH), this is a good indicator for the connection between WASH and stunted growth. To what extent improvements in drinking water safety, toilet use and good handwashing practices contribute to reduce stunting depends on the how bad these practices were prior to interventions.

Heat-related illnesses from occupational heat stress have several risk factors. Some of these factors include high temperatures, humidity, radiant heat sources, limited air movement, metabolic heat from physical exertion of energy, not drinking enough fluids, personal protective equipment and clothing, physical condition and health problems, medications, pregnancy, lack of acclimatization, advanced age, having a previous heat-related illness and others.

Poor maternal nutrition during pregnancy and breastfeeding can lead to stunted growth of their children. Women who are underweight or anemic during pregnancy, are more likely to have stunted children which perpetuates the inter-generational transmission of stunting.

Heat alert programs should be developed for implementation when hotter than normal temperatures, or a heat wave occurs.

Obesity in Mexico is a relatively recent phenomenon, having been widespread since the 1980s with the introduction of processed food into much of the Mexican food market. Prior to that, dietary issues were limited to under and malnutrition, which is still a problem in various parts of the country. Following trends already ongoing in other parts of the world, Mexicans have been foregoing traditional whole grains and vegetables in favor of a diet with more animal products, more fat, and more sugar much of which is a consequence of processed food. It has seen dietary energy intake and rates of overweight and obese people rise with seven out of ten at least overweight and a third clinically obese.

One reason that poverty produces such high rates of fistula cases is the malnutrition that exists in such areas. Lack of money and access to proper nutrition, as well as vulnerability to diseases that exist in impoverished areas because of limited basic health care and disease prevention methods, cause inhabitants of these regions to experience stunted growth. Sub-Saharan Africa is one such environment where the shortest women have on average lighter babies and more difficulties during birth when compared with full-grown women. This stunted growth causes expectant mothers to have skeletons unequipped for proper birth, such as an underdeveloped pelvis. This weak and underdeveloped bone structure increases the chances that the baby will get stuck in the pelvis during birth, cutting off circulation and leading to tissue necrosis. Because of the correlation between malnutrition, stunted growth, and birthing difficulties, maternal height can at times be used as a measure for expected labor difficulties.

While moderate to severe traumatic brain injury is a risk for ALS, it is unclear if mild traumatic brain injury increases rates.

In 1994 the National Institute for Occupational Safety and Health (NIOSH) reported a nonsignificant increase in nervous system disorders due to four cases of ALS among National Football League (NFL) players. It was unclear if this was due to chance or not. Another study from 2012 also found a possible increase in ALS in NFL football players. An older study did not find an increased risk among high school football players. A 2007 review found an increased risk among soccer players. ALS may also occur more often among the US military veterans however the reason is unknown. This may be due to head injury.

After the 2012 report was released, some NFL players involved in the legal settlement with the NFL complained that the NFL, which initially agreed to pay $765 million, was not doing enough to help players. The judge in the case concurred, and the NFL then agreed to pay an unlimited amount of damages for players found to have ALS, Parkinson's disease, Alzheimer's disease and dementia.

High levels of poverty also lead to low levels of education among impoverished women concerning maternal health. This lack of information in combination with obstacles preventing rural women to easily travel to and from hospitals lead many to arrive at the birthing process without prenatal care. This can cause a development of unplanned complications that may arise during home births, in which traditional techniques are used. These techniques often fail in the event of unplanned emergencies, leading women to go to hospital for care too late, desperately ill, and therefore vulnerable to the risks of anesthesia and surgery that must be used on them. In a study of women who had prenatal care and those who had unbooked emergency births, “the death rate in the booked-healthy group was as good as that in many developed countries, [but] the death rate in the unbooked emergencies was the same as the death rate in England in the 16th and 17th centuries.” In this study, 62 unbooked emergency women were diagnosed with obstetric fistulae out of 7,707 studied, in comparison to three diagnosed booked mothers out of 15,020 studied. In addition, studies find that education is associated with lower desired family size, greater use of contraceptives, and increased use of professional medical services. Educated families are also more likely to be able to afford health care, especially maternal healthcare.

Until the late 20th century, dietary issues in Mexico were solely a question of undernutrition or malnutrition, generally because of poverty and distribution issues. For this reason, obesity was associated with wealth and health, the latter especially in children. Despite changes in the Mexican diet and food distribution, malnutrition still remains problematic in various parts of the country.

Patients with severe forms of MJD have a life expectancy of approximately 35 years. Those with mild forms have a normal life expectancy. The cause of death of those who die early is often aspiration pneumonia.

Twelve percent of all infertility cases are a result of a woman either being underweight or overweight. Fat cells produce estrogen, in addition to the primary sex organs. Too much body fat causes production of too much estrogen and the body begins to react as if it is on birth control, limiting the odds of getting pregnant. Too little body fat causes insufficient production of estrogen and disruption of the menstrual cycle. Both under and overweight women have irregular cycles in which ovulation does not occur or is inadequate. Proper nutrition in early life is also a major factor for later fertility.

A study in the US indicated that approximately 20% of infertile women had a past or current eating disorder, which is five times higher than the general lifetime prevalence rate.

A review from 2010 concluded that overweight and obese subfertile women have a reduced probability of successful fertility treatment and their pregnancies are associated with more complications and higher costs. In hypothetical groups of 1000 women undergoing fertility care, the study counted approximately 800 live births for normal weight and 690 live births for overweight and obese anovulatory women. For ovulatory women, the study counted approximately 700 live births for normal weight, 550 live births for overweight and 530 live births for obese women. The increase in cost per live birth in anovulatory overweight and obese women were, respectively, 54 and 100% higher than their normal weight counterparts, for ovulatory women they were 44 and 70% higher, respectively.

According to the American Society for Reproductive Medicine (ASRM), Age, Smoking, Sexually Transmitted Infections, and Being Overweight or Underweight can all affect fertility.

In broad sense, acquired factors practically include any factor that is not based on a genetic mutation, including any intrauterine exposure to toxins during fetal development, which may present as infertility many years later as an adult.

Panayiotopoulos syndrome is probably genetically determined, though conventional genetic influences may be less important than other mechanisms. Usually, there is no family history of similar seizures, although siblings with Panayiotopoulos syndrome or Panayiotopoulos syndrome and rolandic epilepsy or, less common, Panayiotopoulos syndrome and idiopathic childhood occipital epilepsy of Gastaut have been reported. There is a high prevalence of febrile seizures (about 17%).

SCN1A mutations have been reported in a child and in 2 siblings with relatively early onset of seizures, prolonged time over which many seizures have occurred, and strong association of seizures with febrile precipitants even after the age of 5 years. However, no such mutations were found in another couple of siblings and many other cases with typical Panayiotopoulos syndrome. These data indicate that SCN1A mutations when found contribute to a more severe clinical phenotype of Panayiotopoulos syndrome.

About 5–10% of cases are directly inherited from a person's parents. Overall, first-degree relatives of an individual with ALS have a 1% risk of developing ALS.

A defect on chromosome 21, which codes for superoxide dismutase, is associated with about 20% of familial cases of ALS, or about 2% of ALS cases overall. This mutation is believed to be transmitted in an autosomal dominant manner, and has over a hundred different forms of mutation. The most common ALS-causing mutation is a mutant "SOD1" gene, seen in North America; this is characterized by an exceptionally rapid progression from onset to death. The most common mutation found in Scandinavian countries, D90A-SOD1, is more slowly progressive than typical ALS, and people with this form of the disorder survive for an average of 11 years.

In 2011, a genetic abnormality known as a hexanucleotide repeat was found in a region called C9orf72, which is associated with ALS combined with frontotemporal dementia ALS-FTD, and accounts for some 6% of cases of ALS among white Europeans.