|Year : 2017 | Volume
| Issue : 2 | Page : 41-45
Impacts of flood on health: Evidence from northern Iran
Ali Mohajervatan1, Assadollah Karnama2, Zainolabedin Sadeghi2, Zahra Hosseini3, Farideh Alizad4, Masoumeh Dehghani5
1 Attendant Expert of Emergencymanagemen Center (EMS) for Golestan University of Medical Sciences, Golestan Province, Iran
2 Assistant Professor of Faculty of Economics and Department of Management, Bahonar University of Kerman, Iran
3 M.Sc in Environmental Geology and Attendant Expert of Kerman Studying and Training Crisis Management Center, Iran
4 Nurse of 5-Azar Hospital of Golestan University of Medical Sciences, Golestan Province, Iran
5 Graduate Masters in Crisis Management of Bahonar University of Kerman, Kerman, Iran
|Date of Web Publication||31-Aug-2017|
Golestan University of Medical Sciences, Golestan Province
Source of Support: None, Conflict of Interest: None
Introduction: Unexpected events such as floods and earthquakes have long existed in the world and have imposed large losses to society. Every year, these events endanger lives and property of many people all over the world. Floods are the most common of all natural disasters which their consequences depend on factors such as flood causes, geographical location, economic situation, as well as society vulnerability. The aim of this study was to assess the vulnerability of different regions of the Golestan province of Iran to the flooding crisis. Methodology: This retrospective study was done to collect information in the census of all the documentation floods occurred from 1991 to 2013. Results: The results of this study show that 106 floods with frequency 514 have occurred in Golestan province and most severe floods have occurred in the first half of the years (69.8%) occurred. Most losses of human life's due to flooding occurred in the first half of the years. Conclusion: Flood has major impact on health in Golestan province. Therefore, the development of awareness and educational programs on natural disasters must be a priority, because human development largely depends on the ability of society to reduce its vulnerability.
Keywords: Crisis, flash flood, natural hazards, vulnerability
|How to cite this article:|
Mohajervatan A, Karnama A, Sadeghi Z, Hosseini Z, Alizad F, Dehghani M. Impacts of flood on health: Evidence from northern Iran. Int J Health Syst Disaster Manage 2017;5:41-5
|How to cite this URL:|
Mohajervatan A, Karnama A, Sadeghi Z, Hosseini Z, Alizad F, Dehghani M. Impacts of flood on health: Evidence from northern Iran. Int J Health Syst Disaster Manage [serial online] 2017 [cited 2018 Oct 17];5:41-5. Available from: http://www.ijhsdm.org/text.asp?2017/5/2/41/213886
| Introduction|| |
Natural hazards are defined as extreme events that originated on Earth, the lithosphere, hydrosphere, or atmosphere; they are a threat to people and property. The effects of natural hazards in the community are considerable and are clearly increasing. The deaths from storms, floods and earthquakes, and such natural hazards are more than the social and political issues and internal conflicts. Hence, it is clear that more people are affected. Most people exposed to the effects are on developed and developing regions, are from the low-income economic and social spectrum. Iran is a developing country and one of the most prone geographical areas which disasters happen in it. Approximately, 90% of its population is exposed to natural disasters, and in recent decades, in addition to local flooding and slight earthquakes, every 10 years, a national disaster will occur. Natural disasters with devastating effects mainly destroy the ability of a society in ensuring needs and demands. Effects and damage caused by them have the dramatic and undeniable impact on the lives and health of humans so that every year, a large number of people are died and dozens of them wounded and disabled. These events offer unique series of challenges which need a developed series of guidelines particularly when responding to them involve many organizations. During the last four decades, natural disasters such as droughts, floods, and storms are cause of death of human beings, the loss of livelihoods, the economic damage and the destruction of social infrastructure and environmental degradation. In 10 years of the end of 2011, flooding is most common type of disaster in the world, and the cause of half of all victims of natural disasters and economic losses close to $185 billion. Increasing the frequency and severity of flooding is due to rising sea levels and more frequent and intense rainfall; also, one of the most frequently cited impacts of future climate change is a potential increase in the river flood hazard. For example, a warmer climate would increase the risk of floods. In addition, the increasing of urbanization extent means that people are going to be more vulnerable to flood. Flood consequences are including the more patient, making people vulnerable to illness, death, and social disruption and economic, especially in low-income countries, including developing countries that are highly vulnerable. The consequences of the floods on the health depend on factors such as geographical and socioeconomic and also the vulnerability of the affected population , that according to the dimension of time are classified into three categories: short-term, medium-term, and long-term. In the short-term consequences of floods include drowning, burns, skin rashes, and outbreaks of digestive infections and respiratory infections.,, The outcomes in the medium term are including infected wounds, complications from injuries, poisoning, starvation, weakness of mental health, and infectious disease. The potential legacy left by the flood in the long term which can be noted, is chronic illness, disabilities, mental health problems, and nutritional deficiencies., Golestan province, with an area of over 20,437/7 km 2, between 53° and 57 min to 56° 22 min east longitude and 36° and 30 min to 38° and 8 min north latitude in the northern part of the country is located. The province has accounted for 1.2% of the country, is limited from the North to Turkmenistan, from southern Semnan province, from East to North Khorasan province and from the West to the Caspian Sea and Mazandaran province. The province is part of the Caspian Sea basin, which has formed 11.7% of the catchment area of the Caspian Sea and includes Atrak Sofla watershed, Gorgan River, the Ghareh Sou, the East Bay Gorgan, and is Neka River Olya. The area of this watershed is different so that the largest basin in the province is catchment of Gorgan River with 10,120 km 2, and the rest of the basins based on their extent are the catchment of Sofla Atrak by 8600 km 2 and the catchment of Gharehsou 1610 km 2, the catchment of the East Bay Gorgan 340 km 2, and catchment of Olya Neka river with 330 km 2. Golestan province is the most prominent areas in Iran that we saw rain and storm is short in warm seasons. In most cases rainfall has led to severe flooding and devastating especially in the eastern part of the province, that causes large financial damages and human losses, Mr. Lashkary said in a study that the pattern of rainfall in the province follow four types. The first pattern is migratory high pressure pattern, that is, cold advection over the Caspian Sea to European migratory high pressure system and hot and humid convection from East and South East by monsoon low pressure system at ground level and entrance of cold air in the Nawa divergence area of the North Russia which is in the upper levels of the atmosphere over the Caspian Sea, so among floods caused by the system can point to flood August 11, 2001 (according to Iranian calendar 20 Mordad 1380). The second pattern is the pattern of low pressure Sudanese entrance of European migratory high pressure system from North East and flowing polar cold air on the one hand and the entrance of the Sudanese low pressure system from South and South West on the other hand also entrance subtropical high elevation system to the central parts of the Caspian Sea in the middle layers of the atmosphere and locating the Caspian Sea in the Nawa divergence area of the North Aral created this system that the happened flood on August 11, 2001 (according to Iranian calendar 20 Mordad 1380), is caused by this system. The third model is Siberian high pressure caused by cold air advection on the Caspian Sea by the Siberian high pressure system and hot and humid convection in the East and Southeast of the country on the surface and continued hot and humid convection and entrance cold air in behind of the Nawa divergence area on the Caspian Sea. The flood caused by the pattern can be named 1 to 3 September 2000. The fourth type is European pressure pattern and Siberian high pressure, which is caused by the advection of cold air on the surface by European migratory and the Siberian high pressure systems, and warm air and locating the area in front of the deep Nawa of the Black Sea region, along with the heat ridges of middle levels. He concluded that rainfall causing floods in the province follow the four mentioned patterns. Hence, the most severe rainfall follows the second pattern. The study of natural disasters in the past provides the opportunity to have sufficient knowledge and information to prepare for the next disaster. Therefore, this study has aimed to assess the consequences of the floods on the health in the province that a clear picture of the effects of floods on human health as well as an understanding of natural disasters, especially floods during the past two decades displayed in the province.
| Methods|| |
This retrospective study was to gather information and documentation on a census of all floods occurred between 1991 and 2013 has been done in the Golestan province. To collect information on the basis of the available information in the health centers, the Department of Natural Resources has been done. Excel Worksheet was used for data entry. SPSS software was used to analytical statistics. A conventional significance level of P < 0.05 was used. To map vulnerable areas, floods spatial data by GIS software is provided on [Figure 2]. The data in this paper were obtained from the Form flood country. The survey was conducted in all districts of Golestan province [Figure 1]. In each district, a severely flooded commune and a less affected commune (control commune) were selected with reference to the district's Form flood, all information related to the years 1991–2013 has been recorded. There were 514 forms checked out. Data quality was controlled by the field supervisors as well as by the investigators of this survey.
|Figure 2: Distribution of deaths caused by floods in the Golestan province|
Click here to view
Before collecting data, the protocol was submitted to the internal Faculty of Management and Economics Committee Bahonar University adopted. Information has been collected in a neutral investigator.
| Results and Discussion|| |
The results of this study showed that in during 1991 till 2013 in total of 106 cases of rainfall led to flooding had happened in the Golestan province. The most frequent occurrence of rains led to flooding is 13 cases in 2012 (26.12%) and the lowest incidence is related to 2013. The spatial frequency of floods was 514 cases during the study [Table 1].
The results of our study showed that although there is varied climatic in the province, rain was the significant origin for 100% of occurred floods.
Frequency of floods on the season
The results of this study showed that 118 floods happened in July (23%) which is the most frequency. Respectively among other months, floods have occurred in September with a frequency of 85 (16.5%), abundance of 83 (16.1%) in October and August with a frequency of 62 (12.1%) during the study period, also February without flooding among the months of the year to be allocated. According to the results of our study: The highest incidence of floods during the year is related to the summer season with a frequency of 265 (51.6%). Winter flooding with 20% (nine cases) had the lowest incidence during the study period. Three hundred and fifty-eight cases (69.8%) had happened in the first six months and the rest into the second half of year [Table 2].
Relationship between the number of casualties and months
The results of this study showed the relationship between the number of casualties and months of the year showed the greatest human losses in August with a frequency of 375 people 92.6%) and least abundant in November with an abundance of one (0.2%) that the findings determined statistically significant (P = 0.00).
During the 23-year study 514 floods occurred, the information of time interval of rainfall and flood has been recorded in 418 cases that have been analyzed [Table 3]. Studied floods show the most frequent floods (28.9%) have an interval of more than 360 min between the start the end of the precipitation.
|Table 3: The time interval of start rainfall and start flooding of area (n=418)|
Click here to view
Flood and human
The results of this study showed that during the study period, 29 cases of floods in Golestan province (5.6%) had fatal damage. Accordingly, 416 people killed after the flooding, 261 injured, 92 missing. Our results showed that a total of 29 floods led to casualties, only depth of flooding of 18 cases has been documented.
Relation death and flooded depth
The analysis was conducted based on 18 floods, and the results showed that 75.4% of the human losses had happened in areas with 300 cm depth of flooding, which showed statistically significant difference (P = 0.00) [Table 4].
Our results show that everything we move from west to east in Golestan province The number of deaths from floods is increased and Major floods occur in the foothills where the concentration of population is located. According to the results of this study, in Golestan province with cultural, social, geographical, and specific ethnic diversity, flooding is one of the main disasters. The study results showed that rainfall has been caused 100% of the flooding and during the study floods caused by waves and melting snow have not occurred. Furthermore, findings determined that in 1991–2013, 106 precipitations led to the flood which happened in 514 areas. During the past 22 years, flooding occurred in average of 23 points per year and had economic losses over 667,912/3674 billion. It seems that our results would agree with statistics released by the international (in the 10 years before 2011) that the flood was responsible for almost half of the victims of natural disasters and cause economic losses of nearly 185 billion. The number of recorded floods in 1991 was three flood; the statistic in 2012 has reached to 13. It seems that flooding has caused by increasing in the frequency and severity of rainfall and rising sea level. In addition, extending of urbanization means that people are more at risk of flooding. Check occurred floods in Golestan province showed that most floods had happened in summer (with 51.67%). During the months of the year, the floods with a frequency of 23% were in July. The results of our analysis of flooding occurred in different parts of the province showed that the interval time of starting precipitation until starting flood, in less than 27% of cases at different points was less than 60 min. Moreover, in more than 70% of cases was greater than 60 min. The results of this study showed that in less than 18% of cases, the duration of flood waterlogging was less than 360 minutes(6 hours) And in other cases more than 360 minutes(6 hours). The immediate consequences of the floods on the health in the Golestan were including deaths and injuries. Our study showed that during the study period, 416 deaths, 261 injured and 92 people were lost. It seems that the impression of placing people at risk of flooding would be caused kills and injuries, is true in Golestan province. Floods in Golestan province have caused deaths more than other disasters and natural calamities. Comprehensive study on the deaths of other natural disasters does not exist in Golestan province, which determines ratio of deaths caused by floods to all deaths, but it seems that our result agrees with the findings of other studies,, in which, floods are responsible for 40%–50% of deaths from natural disasters. The results of this study showed that most deaths in floods were 254 people and related to the flood in August 2001, although this study due to lack of information about the medium- and long-term consequences has examined only the immediate effects of the floods on the health sector. However, it is thought that flood will increase plethora of diseases and expose people at risk of disease, death, social disruption, and economic, and a constant psychological stress for achieving health services as well. The immediate health effects of floods recognized include: drowning, injuries, acute asthma, skin rashes, diarrhea and vomiting and respiratory infections. Medium-term effects of flooding include wound infections, complications from injuries, poisoning, poor mental health, infectious disease, and hunger., Long-term chronic illness, disability, and poor mental health, poverty-related diseases including malnutrition threaten society. Flooding long-term effects on health from disease or other damage might be even more important because the psychological problems caused by flood events may subside for a longer time after the flood continues., It seems that potential need for understanding the medium- and long-term effects of floods remains in Golestan province and it is necessary to keep in mind these aspects for further study. Our findings suggest that mitigation program and also increase the preparation has affected on the decreasing of the number of deaths from flooding in the past to the present, but it seems that the need to improve understanding of hazard and the health damage and its consequences on people's health still remains potential. Our results show that there is a significant correlation in the relationship between the flood (of the location) and the time interval of rainfall to start flooding; About 75% of the deaths occurred in floods, the time interval between the start of rainfall and the beginning of the flood was very shorted. This shows that flash floods have a strong role in the creation of human damage. The findings corresponded to the study last  where flash floods occurred in summer and can cause serious injuries. It seems that the employed strategy for controlling of these floods should vary with other floods and be more focused on prediction and early warning to affected areas, that is based on flood evacuation; in this way, we will see a decline in injuries. The results of this study show that there is a significant relationship between the mortality and the depth of the flooding caused by the floods. This means that more than 75% of deaths occurred in floods of more than 300 cm flooding depth, and so increasing the water level plays an important role in increasing death. Using the ways, which are continuously exploring the flowing water volume in rivers and flood areas, can be effective in evacuating affected areas and thus reducing the damage. It seems that the development of awareness programs and training in natural disasters in Golestan province Must be given priority. Programs to improve the methods of forecasting and warning dissemination should be expanded and intensified.
| Conclusion|| |
Flood has major impact on health, agriculture, and housing in Golestan province. Therefore, the development of awareness and educational programs on natural disasters must be a priority, because human development largely depends on the ability of society to reduce its vulnerability hazard.
This article is extracted from Master's Thesis of shahid bahonar Kerman, Iran, and the authors would like to thank all those who have contributed to this article.
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[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3], [Table 4]


Many patients struggle to swallow medications may use substances such as yoghurt, fruit puree or jam to assist with swallowing (See our previous post ‘Gloup vs Food‘).
If this still doesn’t work, they may resort to crushing the medication.
Modern medicines are often very sophisticated, many are made using techniques which influence how they are absorbed by the body. For example, some tablets have a covering on them to protect your stomach from the medication or protect your medication from being attacked by stomach acid.
In Australia, they have a campaign called ‘Don’t Rush to Crush.’
“Don’t Rush to Crush provides information at the point of care that helps ensure patients receive their medicines in a manner that is safe and maintains medication efficacy.”
Editorial Chair and SHPA Board Director Dr Lisa Pont
It’s a resource for pharmacists and nurses described as an “essential guide to safely administering oral medicines to people with enteral feeding tubes or swallowing difficulties”.
What can we learn from Don’t Rush to Crush?
Crushing tablets that aren’t designed to be taken in this way may cause serious side effects; it could even slow down recovery from illness, prevent the medicine from working properly or result in incorrect dosage.
It is vitality important that you or your caregiver check the information leaflet which accompanies your medication, it will often state if you can crush your tablets or open your capsules if it doesn’t then be sure to ask your doctor or pharmacist for more information.
The image below shows abbreviations that could be used to describe slow-release medications.
Image source: https://ww2.health.wa.gov.au/
Recent guidelines for health care professionals state that they should always ask the patient about swallowing difficulties before prescribing medicines. If you haven’t been asked to make sure you tell your doctor, nurse or pharmacist that you’re having a problem. There are solutions that can help you.
Gloup – The Safe Alternative to Crushing medication.
Gloup is a medical tool that has been designed in response to a growing need for support to caregivers in providing medicine to patients. Gloup is:
- Safe as water – doesn’t interfere with medication
- Solution inspired- meeting an existing need
- Has a pleasant taste – encourages regular use and effective medication consumption
Gloup’s solution is simplicity itself. A lightweight, smooth gel, it allows tablets to be swallowed as easily as a spoonful of yoghurt, or a sip of soup. It simply covers the tablet on the spoon, to allow for its safe transportation – so it can get to work in the way it was designed to.
Find out more: https://gloup.shop/for-patients/carers/


Sarah Wiggum would like to make a single investment and have $2.9 million at the time of her retirement in 25 years. She has found a mutual fund that will earn 3 percent annually. How much will Sarah have to invest today? If Sarah invests that amount and could earn a 15 percent annual return, how soon could she retire, assuming she is still going to retire when she has $2.9million? To have $2.9 million at retirement, the amount Sarah must invest today is $______? .
https://assignmentspool.com/wp-content/uploads/2021/01/logo-300x60.png 0 0 Davie https://assignmentspool.com/wp-content/uploads/2021/01/logo-300x60.png Davie2019-06-29 00:08:332019-06-29 00:08:33Sarah Wiggum


Psychiatric advance directives permit people to determine what treatment they will receive if and when they lose the capacity to make treatment decisions. Mental Health America supports and promotes the use of psychiatric advance directives as a tool for the expression of an individual's free will and self-determination in coping with mental health and substance use conditions. State laws regulate advance directives, and compliance is strongly advised. Resources include:
Mental Health America (MHA) is dedicated to promoting mental health, preventing mental health and substance use disorders and achieving victory over mental illnesses and substance abuse and dependency through advocacy, education, research and service. One of MHA’s goals is the development of a broad-based national research agenda that includes basic research, diagnostic and treatment research, services research and prevention research.
As elaborated in Position Statement 31, Mental Health America ("MHA") believes that people in recovery from mental illness or addiction need an array of integrated services that includes, in particular, access to paid employment. This is especially true for people residing in and transitioning from treatment facilities, who must be prepared for life outside of the facility.
Mental Health America (MHA) believes that effective protection of human rights and the best hope for recovery from mental illness comes from access to voluntary mental health treatment and services that are comprehensive, community-based, recovery-oriented and culturally and linguistically competent.
Mental Health America (MHA) supports careful implementation and clarification of the standards of confidentiality incorporated in the Health Information Portability and Accountability Act of 1996 ("HIPAA"), with the following additions: flexibility in emergency situations; requirement of minor assent as well as parental consent; appointment of a guardian when needed; mandatory reporting of child and elder abuse; lack of confidentiality in custody disputes; exceptions for court orders; and special protection of treatment re
Seclusion and restraints have no therapeutic value, contribute to human suffering, and have frequently resulted in severe emotional and physical harm, and death1. Therefore, as a matter of fundamental policy, Mental Health America (MHA) urges abolition of the use of seclusion and restraints to control symptoms of mental illnesses, and prohibition of the use of sedatives and other medications as chemical restraints.


Sap is where pancake syrup comes from, resin clogs your smoking pipes, and pitch is what you do with a ball, right? Well, not quite, close though. Sap is the lifeblood of trees or other plants, but usually when we refer to sap we are thinking in terms of a tree. Sap runs through the outer layer of a tree. If you were to cut through the bark and outer most layer of a tree, all the way around the tree, the tree will die.
Respect the Trees
This is why in survival situations if you are utilizing natural elements, you must consider the damage you are doing to the tree. A tree is a living, breathing organism. If you use it for materials needed for, say, making pitch to seal a vessel, or a canoe, or for affixing an arrowhead to an arrow, you must respect it and treat it as such so that it continues to live and breathe and provide materials for you.
Look for Naturally Occurring Resin
If you must collect resin from trees, look at several trees and try to find an area that is already secreting sap and gather that, rather than injuring the tree yourself for the intention of gathering sap for pitch or other uses. It should be mentioned that the best time for collecting sap is in the early spring when the sap is running. It can be done at other times of the year, but with greatly reduced results.
The “V” Cut
If you find that you MUST wound a tree to collect sap for pitch, or whatever use you intend, one method for doing so is to use your hatchet or knife and cut a “V” into the tree. Then use another piece of stick that you have sharpened to a point and flattened, insert that stick into the bottom of the “V,” and the sap will run and drip off the stick into a collection vessel.
If you find naturally occurring injury areas on the tree, you can collect the hardened resin from that area. If you were to collect that resin and mix it with charcoal dust, then it becomes a form of pitch. The terms pitch and resin are often used interchangeably.
READ FULL ARTICLE HERE
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In this blog, I’m explaining the abstraction and
In the Object oriented programming’s, Abstraction is one of
the principle of object oriented programming.
Abstraction is the process of separating ideas from specific instances
of those ideas at work. Abstraction means to show only the necessary details to
the client of the object. For example, take a look at your mouse. Is it
wireless? What kind of sensor does it have? How many buttons? Is it ergonomic?
How big is it? The answers to all of these questions can precisely describe
your mouse, but regardless of what the answers are, it's still a mouse, because
it's a pointing device with buttons. That's all it takes to be a mouse.
"Silver Logitech MX518" is a concrete, specific item, and
"mouse" is an abstraction of that. An important thing to think about
is that there's no such concrete object as a "mouse", it's just an
idea. The mouse on your desk is always something more specific - it's an Apple
Magic Mouse or a Dell Optical Mouse or a Microsoft IntelliMouse -
"mouse" is just an abstract concept. Let us take the example of our
laptop Keyboard itself, here we have a number of Keys, each performing some
function dependent on the value given. Now all keys have a certain value that
is accepted by the CPU when you press it. So we create a common object called
Key with methods. This is abstraction show only the details which matter to the
Encapsulation is the term of Object Oriented Programming
concept. Encapsulation like a capsule (medicine tablet) which hides medicine
inside it. The wrapping up of attributes and behaviors into a single unit
entity is called as encapsulation. Class is the best example of encapsulation.
In Encapsulation increase the accessibility level of protection. Now if we
consider a laptop, as an end user I have access only to some features of the
system. So I could use the mouse to move the cursor, or the keyboard for typing
text, but I would not have access to the internal components of the laptop.
Again the keyboard in turn is bound internally to a set of methods that operate
in response to a user action or an event.


The finest and most fascinating of the emperor Trajan's monuments is without a doubt Trajan's column, erected between the Greek and Latin libraries in front of the Basilica Ulpia in the Forum of Trajan. The column itself is more than 3m in diameter and rises to a height of 38m (100 Roman feet), and was constructed in 110 AD of 17 drums of marble from the Aegean island of Paros. Ascending in a spiral around the column is a continuous frieze more than 200m long, depicting in 23 turns of carved relief Trajan's military campaign against the Dacians. Contained within the frieze are around 2500 figures in 155 not-always-easily-distinguishable scenes; the frieze is separated from itself by a rough-cut band of varying thickness of the sort that, in Roman sculpture, typically represents earth. The column was originally topped with a statue of Trajan, which has since been replaced by a statue of St. Peter.
While this sort free-standing, decorated column seems to have been an entirely new form of expression (loosely based, perhaps, on Egyptian obelisks), much about the execution of the reliefs is clearly Greek in descent. The figures are typically well-proportioned, although their heads are slightly larger in relation to their bodies than Late Classical Greek works. The exception to this is the depiction of slain Romans and barbarians - their corpses are subtly out of proportion, distorted to emphasize their twisted, crumpled nature. In contrast to the earlier-style head-body proportions, this distortion mirrors much later Greek trends, first seen in some works at Pergamum. The figures on the column are often clad in some form of drapery (the barbarians' loose-fitting clothes, or Romans wearing cloaks over their armor) and when this is the case, the drapery looks very classically Greek - swirling in backdrop to the action and outlining the forms of the figures. However, the Roman artists stopped short of the Greek florid style, either in keeping with the earlier Classical proportions, or perhaps feeling that such ornamentation was not fitting to a monument to a down-to-earth Iberian soldier like Trajan.
The major theme of the column is the typically Greek triumph of civilization over barbarism, but the differentiation of civilization and barbarism is done in a very Roman fashion - with a specific, propagandistic aim in mind. The Romans are depicted as living embodiments of the Roman virtues of reason, industriousness, and discipline. The Roman soldiers on the frieze are constantly engaged in the actions that the Romans felt made them great and thus fated to overcome the forces of barbarism and chaos. The soldiers display their ratio and disciplina by fighting in organized formations, clad in standardized armor and armed with similar weapons. They are constantly exhibiting the Roman predilection for labor - when they are not fighting, they are building walls, bridges, or fortified camps. Furthermore, Trajan and the other Romans display virtus in their orderly treatment of prisoners and their clementia when accepting surrender. The Dacians are depicted as sympathetic and worthy adversaries, but sadly lacking in Roman virtues - they fight in wild mobs and build no walls or bridges; they treat their Roman prisoners with barbaric cruelty. Thus, the battle of civilization and barbarity is firmly cast in terms of a battle between Roman virtues and a lack thereof, and the inevitable victory is that of the Romans as ideals of virtue and industriousness.
Thus, while the techniques and proportions used to depict the forms of the figures is classically Greek, the manner in which the figures are portrayed is new and unique. Figures on the column are shown neither as idealized human archetypes nor as entirely accurate, true-to-life portraits, but rather as individuals possessed of an enhanced humanity. That is, they no longer are shown as ideal humans or real humans, but rather human ideals. This is well illustrated by the scene in which Trajan and his general Sura address the Roman troops. Trajan is identifiable by his features, but those features and his bearing are enhanced in order to portray Trajan as the perfect statesman and leader - obviously, a role the Romans wanted their emperor to fill. Likewise, in another scene, Trajan charges into battle with his arm raised as if to hurl forth thunderbolts in the manner of Jupiter. Here, Trajan is portrayed as the embodiment of the perfect warrior emperor, whose greatest function is to appear terrible to the Empire's enemies. Such portrayal of individuals fitting into perfected roles is not restricted to Trajan alone, either. Sura is depicted as an identifiable character who also happens to exude loyalty, inspiration, and battle-readiness, and each and every Roman soldier appears both as a man and as a living cog in the great machine of Roman civilization.
Even the Dacians are cast to fit into the slot the Romans felt they should occupy - the worthy adversary who nevertheless is doomed to defeat by a barbarous nature and lack of "Romanity." The artists who crafted the column portrayed the Dacians in a very sympathetic manner - the depiction of the Dacians fleeing their villages and enduring hardships is perhaps the kindest portrayal of an enemy to be found in the ancient world. This is a mark of the Roman mindset in the time of the Good Emperors - confident enough to be magnanimous and generous to their enemies, certain of their place - and that of their enemies - in the great order of the world.
Trajan's column is a work both of monumental greatness (Constantine is said to have sulked for three days after seeing Trajan's forum and column, for none of his own works could surpass it) and a work that demonstrates the evolution of the Romans' Greek artistic heritage. The Romans used Greek techniques and proportions to portray their characters and yet introduced their own enhancements - figures had grooves around them to enhance their relief and background details were sunken into the surface to give a greater feeling of depth. The Romans used Greek themes - the battle of the civilized and the barbaric - in new ways to express their own world views. Finally, the Romans moved away from both the Greek humanist ideal and their own earlier realism to portray people as both individuals and embodiments of idealized virtues.
I used information from Ranuccio Bandinelli's Rome, the Center of Power: 500BC - 200AD, Niels Hannestad's Roman Art and Imperial Policy, John Pedley's Greek Art and Archaeology, and John Wickstrom's lectures on "Late Antiquity and the Early Middle Ages" to prepare the report that I condensed into this writeup. Check out evilrooster's excellent writeup on the Forum of Trajan for more info on the column's environs.


This article needs attention from an expert in medicine.May 2018)(
Right human eye cross-sectional view; eyes vary significantly among animals.
|Artery||Central retinal artery|
The retina is the innermost, light-sensitive layer of tissue of the eye of most vertebrates and some molluscs. The optics of the eye create a focused two-dimensional image of the visual world on the retina, which translates that image into electrical neural impulses to the brain to create visual perception, the retina serving a function analogous to that of the film or image sensor in a camera.
The neural retina consists of several layers of neurons interconnected by synapses, and is supported by an outer layer of pigmented epithelial cells. The primary light-sensing cells in the retina are the photoreceptor cells, which are of two types: rods and cones. Rods function mainly in dim light and provide black-and-white vision. Cones function in well-lit conditions and are responsible for the perception of colour, as well as high-acuity vision used for tasks such as reading. A third type of light-sensing cell, the photosensitive ganglion cell, is important for entrainment of circadian rhythms and reflexive responses such as the pupillary light reflex.
Light striking the retina initiates a cascade of chemical and electrical events that ultimately trigger nerve impulses that are sent to various visual centres of the brain through the fibres of the optic nerve. Neural signals from the rods and cones undergo processing by other neurons, whose output takes the form of action potentials in retinal ganglion cells whose axons form the optic nerve. Several important features of visual perception can be traced to the retinal encoding and processing of light.
In vertebrate embryonic development, the retina and the optic nerve originate as outgrowths of the developing brain, specifically the embryonic diencephalon; thus, the retina is considered part of the central nervous system (CNS) and is actually brain tissue. It is the only part of the CNS that can be visualized non-invasively.
The vertebrate retina is inverted in the sense that the light sensing cells are in back of the retina, so that light has to pass through layers of neurons and capillaries before it reaches the rods and cones. The ganglion cells, whose axons form the optic nerve, are at the front of the retina; therefore the optic nerve must cross through the retina en route to the brain. In this region there are no photoreceptors, giving rise to the blind spot. In contrast, in the cephalopod retina the photoreceptors are in front, with processing neurons and capillaries behind them. Because of this, cephalopods do not have a blind spot.
Although the overlying neural tissue is partly transparent, and the accompanying glial cells have been shown to act as fibre-optic channels to transport photons directly to the photoreceptors, light scattering does occur. Some vertebrates, including humans, have an area of the central retina adapted for high-acuity vision. This area, termed the fovea centralis, is avascular (does not have blood vessels), and has minimal neural tissue in front of the photoreceptors, thereby minimizing light scattering.
The cephalopods have a non-inverted retina which is comparable in resolving power to the eyes of many vertebrates. Squid eyes do not have an analog of the vertebrate retinal pigment epithelium (RPE). Although their photoreceptors contain a protein, retinochrome, that recycles retinal and replicates one of the functions of the vertebrate RPE, one could argue that cephalopod photoreceptors are not maintained as well as in vertebrates and that, as a result, the useful lifetime of photoreceptors in invertebrates is much shorter than in vertebrates. Having easily replaced stalk-eyes (some lobsters) or retinae (some spiders, such as Deinopis) rarely occurs.
The cephalopod retina does not originate as an outgrowth of the brain, as the vertebrate one does. It is arguable that this difference shows that vertebrate and cephalopod eyes are not homologous but have evolved separately. From an evolutionary perspective, a more complex structure such as the inverted retina can generally come about as a consequence of two alternate processes: (a) an advantageous "good" compromise between competing functional limitations, or (b) as a historical maladaptive relic of the convoluted path of organ evolution and transformation. Vision is an important adaptation in higher vertebrates.
A third view of the "inverted" vertebrate eye is that it combines two benefits: the maintenance of the photoreceptors mentioned above, and the reduction in light intensity necessary to avoid blinding the photoreceptors, which are based on the extremely sensitive eyes of the ancestors of modern hagfishes (a fish that lives in very deep, dark water).
The vertebrate retina has ten distinct layers. From closest to farthest from the vitreous body:
These layers can be grouped into 4 main processing stages: photoreception; transmission to bipolar cells; transmission to ganglion cells, which also contain photoreceptors, the photosensitive ganglion cells; and transmission along the optic nerve. At each synaptic stage there are also laterally connecting horizontal and amacrine cells.
The optic nerve is a central tract of many axons of ganglion cells connecting primarily to the lateral geniculate body, a visual relay station in the diencephalon (the rear of the forebrain). It also projects to the superior colliculus, the suprachiasmatic nucleus, and the nucleus of the optic tract. It passes through the other layers, creating the optic disc in primates.
Additional structures, not directly associated with vision, are found as outgrowths of the retina in some vertebrate groups. In birds, the pecten is a vascular structure of complex shape that projects from the retina into the vitreous humour; it supplies oxygen and nutrients to the eye, and may also aid in vision. Reptiles have a similar, but much simpler, structure.
In adult humans, the entire retina is approximately 72% of a sphere about 22 mm in diameter. The entire retina contains about 7 million cones and 75 to 150 million rods. The optic disc, a part of the retina sometimes called "the blind spot" because it lacks photoreceptors, is located at the optic papilla, where the optic-nerve fibres leave the eye. It appears as an oval white area of 3 mm². Temporal (in the direction of the temples) to this disc is the macula, at whose centre is the fovea, a pit that is responsible for our sharp central vision but is actually less sensitive to light because of its lack of rods. Human and non-human primates possess one fovea, as opposed to certain bird species, such as hawks, who are bifoviate, and dogs and cats, who possess no fovea but a central band known as the visual streak. Around the fovea extends the central retina for about 6 mm and then the peripheral retina. The farthest edge of the retina is defined by the ora serrata. The distance from one ora to the other (or macula), the most sensitive area along the horizontal meridian is about 32 mm.[clarification needed]
In section, the retina is no more than 0.5 mm thick. It has three layers of nerve cells and two of synapses, including the unique ribbon synapse. The optic nerve carries the ganglion cell axons to the brain, and the blood vessels that supply the retina. The ganglion cells lie innermost in the eye while the photoreceptive cells lie beyond. Because of this counter-intuitive arrangement, light must first pass through and around the ganglion cells and through the thickness of the retina, (including its capillary vessels, not shown) before reaching the rods and cones. Light is absorbed by the retinal pigment epithelium or the choroid (both of which are opaque).
The white blood cells in the capillaries in front of the photoreceptors can be perceived as tiny bright moving dots when looking into blue light. This is known as the blue field entoptic phenomenon (or Scheerer's phenomenon).
Between the ganglion cell layer and the rods and cones there are two layers of neuropils where synaptic contacts are made. The neuropil layers are the outer plexiform layer and the inner plexiform layer. In the outer neuropil layer, the rods and cones connect to the vertically running bipolar cells, and the horizontally oriented horizontal cells connect to ganglion cells.
The central retina predominantly contains cones, while the peripheral retina predominantly contains rods. In total, there are about seven million cones and a hundred million rods. At the centre of the macula is the foveal pit where the cones are narrow and long, and, arranged in a hexagonal mosaic, the most dense. At the foveal pit the other retinal layers are displaced, before building up along the foveal slope until the rim of the fovea, or parafovea, is reached, which is the thickest portion of the retina. The macula has a yellow pigmentation, from screening pigments, and is known as the macula lutea. The area directly surrounding the fovea has the highest density of rods converging on single bipolar cells. Since its cones have a much lesser convergence of signals, the fovea allows for the sharpest vision the eye can attain.
Though the rod and cones are a mosaic of sorts, transmission from receptors, to bipolars, to ganglion cells is not direct. Since there are about 150 million receptors and only 1 million optic nerve fibres, there must be convergence and thus mixing of signals. Moreover, the horizontal action of the horizontal and amacrine cells can allow one area of the retina to control another (e.g. one stimulus inhibiting another). This inhibition is key to lessening the sum of messages sent to the higher regions of the brain. In some lower vertebrates (e.g. the pigeon), there is a "centrifugal" control of messages - that is, one layer can control another, or higher regions of the brain can drive the retinal nerve cells, but in primates this does not occur.
From innermost to outermost, the layers identifiable by OCT are as follows:
|#||OCT Layer / Conventional Label||Anatomical Correlate||Reflectivity||Specific
|1||Posterior cortical vitreous||Posterior cortical vitreous||Hyper-reflective||Yes|||
|2||Preretinal space||In eyes where the vitreous has fully or partially detached from the retina, this is the space created between the posterior cortical vitreous face and the internal limiting membrane of the retina.||Hypo-reflective|||
|3||Internal limiting membrane (ILM)||Formed by Müller cell endfeet
(unclear if it can be observed on OCT)
|Nerve fiber layer (NFL)||Ganglion cell axons travelling towards the optic nerve|
|4||Ganglion cell layer (GCL)||Ganglion cell bodies (and some displaced amacrine cells)||Hypo-reflective|||
|5||Inner plexiform layer (IPL)||Synapses between bipolar, amacrine and ganglion cells||Hyper-reflective|||
|6||Inner nuclear layer (INL)||a) Horizontal, bipolar and amacrine cell bodies
b) Müller cell nuclei
|7||Outer plexiform layer (OPL)||Synapses between photoreceptor, bipolar and horizontal cells||Hyper-reflective|||
|8||(Inner half) Henle's nerve fiber layer (HL)||Photoreceptor axons
(obliquely orientated fibres; not present in mid-peripheral or peripheral retina)
|(Outer half) Outer nuclear layer (ONL)||The photoreceptor cell bodies|
|9||External limiting membrane (ELM)||Made of zonulae adherens between Müller cells and photoreceptor inner segments||Hyper-reflective|||
|10||Myoid zone (MZ)||The innermost portion of the photoreceptor inner segment (IS) containing:||Hypo-reflective||No|||
|11||Ellipsoid zone (EZ)||The outermost portion of the photoreceptor inner segment (IS) packed with mitochondria||Very Hyper-reflective||No|||
|IS/OS junction or Photoreceptor integrity line (PIL)||The photoreceptor connecting cilia which bridge the inner and outer segments of the photoreceptor cells.|
|12||Photoreceptor outer segments (OS)||The photoreceptor outer segments (OS) which contain disks filled with opsin, the molecule that absorbs photons.||Hypo-reflective|||
|13||Interdigitation zone (IZ)||Apices of the RPE cells which encase part of the cone OSs.
Poorly distinguishable from RPE. Previously: "cone outer segment tips line" (COST)
|14||RPE/Bruch's complex||RPE phagosome zone||Very Hyper-reflective||No|||
|RPE melanosome zone||Hypo-reflective|
|RPE mitochondria zone + Junction between the RPE & Bruch's membrane||Very Hyper-reflective|
|15||Choriocapillaris||Thin layer of moderate reflectivity in inner choroid||No|||
|16||Sattler's layer||Thick layer of round or ovalshaped hyperreflective profiles, with hyporeflective cores in mid-choroid|||
|17||Haller's layer||Thick layer of oval-shaped hyperreflective profiles, with hyporeflective cores in outer choroid|||
|18||Choroidal-scleral juncture||Zone at the outer choroid with a marked change in texture, in which large circular or ovoid profiles abut a
homogenous region of variable reflectivity
Retinal development begins with the establishment of the eye fields mediated by the SHH and SIX3 proteins, with subsequent development of the optic vesicles regulated by the PAX6 and LHX2 proteins. The role of Pax6 in eye development was elegantly demonstrated by Walter Gehring and colleagues, who showed that ectopic expression of Pax6 can lead to eye formation on Drosophila antennae, wings, and legs. The optic vesicle gives rise to three structures: the neural retina, the retinal pigmented epithelium, and the optic stalk. The neural retina contains the retinal progenitor cells (RPCs) that give rise to the seven cell types of the retina. Differentiation begins with the retinal ganglion cells and concludes with production of the Muller glia. Although each cell type differentiates from the RPCs in a sequential order, there is considerable overlap in the timing of when individual cell types differentiate. The cues that determine a RPC daughter cell fate are coded by multiple transcription factor families including the bHLH and homeodomain factors.
In addition to guiding cell fate determination, cues exist in the retina to determine the dorsal-ventral (D-V) and nasal-temporal (N-T) axes. The D-V axis is established by a ventral to dorsal gradient of VAX2, whereas the N-T axis is coordinated by expression of the forkhead transcription factors FOXD1 and FOXG1. Additional gradients are formed within the retina. This spatial distribution may aid in proper targeting of RGC axons that function to establish the retinotopic map.
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The retina is stratified into distinct layers, each containing specific cell types or cellular compartments that have metabolisms with different nutritional requirements. To satisfy these requirements, the ophthalmic artery bifurcates and supplies the retina via two distinct vascular networks: the choroidal network, which supplies the choroid and the outer retina, and the retinal network, which supplies the retina's inner layer.
At first glance, one may think that the vertebrate retina is "wired wrongly" or "badly designed"; but in fact, the retina could not function if it were not inverted. The photoreceptor layer must be embedded in the retinal pigment epithelium (RPE), which performs at least seven vital functions, one of the most obvious being to supply oxygen and other necessary nutrients needed for the photoreceptors to function. These nutrients include glucose, fatty acids, and retinal. The mammalian photoreceptor amplification process uses large quantities energy for vision in photopic conditions (requiring less under scotopic conditions) and, thus, requires the large supply nutrients supplied by the blood vessels in the choroid, which lies beyond the RPE. The choroid supplies about 75% of these nutrients to the retina and the retinal vasculature only 25%.
When light strikes 11-cis-retinal (in the disks in the rods and cones), 11-cis-retinal changes to all-trans-retinal which then triggers changes in the opsins. Now, the outer segments do not regenerate the retinal back into the cis- form once it has been changed by light. Instead the retinal is pumped out to the surrounding RPE where it is regenerated and transported back into the outer segments of the photoreceptors. This recycling function of the RPE protects the photoreceptors against photo-oxidative damage and allows the photoreceptor cells to have decades-long useful lives.
The bird retina is devoid of blood vessels, perhaps to give unobscured passage of light for forming images, thus giving better resolution. It is, therefore, a considered view that the bird retina depends for nutrition and oxygen supply on a specialized organ, called the "pecten" or pecten oculi, located on the blind spot or optic disk. This organ is extremely rich in blood vessels and is thought to supply nutrition and oxygen to the bird retina by diffusion through the vitreous body. The pecten is highly rich in alkaline phosphatase activity and polarized cells in its bridge portion - both befitting its secretory role. Pecten cells are packed with dark melanin granules, which have been theorized to keep this organ warm with the absorption of stray light falling on the pecten. This is considered to enhance metabolic rate of the pecten, thereby exporting more nutritive molecules to meet the stringent energy requirements of the retina during long periods of exposure to light.
The bifurcations and other physical characteristics of the inner retinal vascular network are known to vary among individuals, and these individual variances have been used for biometric identification and for early detection of the onset of disease. The mapping of vascular bifurcations is one of the basic steps in biometric identification. Results of such analyses of retinal blood vessel structure can be evaluated against the ground truth data of vascular bifurcations of retinal fundus images that are obtained from the DRIVE dataset. In addition, the classes of vessels of the DRIVE dataset have also been identified, and an automated method for accurate extraction of these bifurcations is also available. Changes in retinal blood circulation are seen with aging and exposure to air pollution, and may indicate cardiovascular diseases such as hypertension and atherosclerosis. Determining the equivalent width of arterioles and venules near the optic disc is also a widely used technique to identify cardiovascular risks.
The retina translates an optical image into neural impulses starting with the patterned excitation of the colour-sensitive pigments of its rods and cones, the retina's photoreceptor cells. The excitation is processed by the neural system and various parts of the brain working in parallel to form a representation of the external environment in the brain.
The cones respond to bright light and mediate high-resolution colour vision during daylight illumination (also called photopic vision). The rod responses are saturated at daylight levels and don't contribute to pattern vision. However, rods do respond to dim light and mediate lower-resolution, monochromatic vision under very low levels of illumination (called scotopic vision). The illumination in most office settings falls between these two levels and is called mesopic vision. At mesopic light levels, both the rods and cones are actively contributing pattern information. What contribution the rod information makes to pattern vision under these circumstances is unclear.
The response of cones to various wavelengths of light is called their spectral sensitivity. In normal human vision, the spectral sensitivity of a cone falls into one of three subtypes, often called blue, green, and red, but more accurately known as short, medium, and long wavelength-sensitive cone subtypes. It is a lack of one or more of the cone subtypes that causes individuals to have deficiencies in colour vision or various kinds of colour blindness. These individuals are not blind to objects of a particular colour, but are unable to distinguish between colours that can be distinguished by people with normal vision. Humans have this trichromatic vision, while most other mammals lack cones with red sensitive pigment and therefore have poorer dichromatic colour vision. However, some animals have four spectral subtypes, e.g. the trout adds an ultraviolet subgroup to short, medium, and long subtypes that are similar to humans. Some fish are sensitive to the polarization of light as well.
In the photoreceptors, exposure to light hyperpolarizes the membrane in a series of graded shifts. The outer cell segment contains a photopigment. Inside the cell the normal levels of cyclic guanosine monophosphate (cGMP) keep the Na+ channel open, and thus in the resting state the cell is depolarised. The photon causes the retinal bound to the receptor protein to isomerise to trans-retinal. This causes the receptor to activate multiple G-proteins. This in turn causes the Ga-subunit of the protein to activate a phosphodiesterase (PDE6), which degrades cGMP, resulting in the closing of Na+ cyclic nucleotide-gated ion channels (CNGs). Thus the cell is hyperpolarised. The amount of neurotransmitter released is reduced in bright light and increases as light levels fall. The actual photopigment is bleached away in bright light and only replaced as a chemical process, so in a transition from bright light to darkness the eye can take up to thirty minutes to reach full sensitivity.
When thus excited by light, the photoceptor sends a proportional response synaptically to bipolar cells which in turn signal the retinal ganglion cells. The photoreceptors are also cross-linked by horizontal cells and amacrine cells, which modify the synaptic signal before it reaches the ganglion cells, the neural signals being intermixed and combined. Of the retina's nerve cells, only the retinal ganglion cells and few amacrine cells create action potentials.
In the retinal ganglion cells there are two types of response, depending on the receptive field of the cell. The receptive fields of retinal ganglion cells comprise a central, approximately circular area, where light has one effect on the firing of the cell, and an annular surround, where light has the opposite effect. In ON cells, an increment in light intensity in the centre of the receptive field causes the firing rate to increase. In OFF cells, it makes it decrease. In a linear model, this response profile is well described by a difference of Gaussians and is the basis for edge detection algorithms. Beyond this simple difference, ganglion cells are also differentiated by chromatic sensitivity and the type of spatial summation. Cells showing linear spatial summation are termed X cells (also called parvocellular, P, or midget ganglion cells), and those showing non-linear summation are Y cells (also called magnocellular, M, or parasol retinal ganglion cells), although the correspondence between X and Y cells (in the cat retina) and P and M cells (in the primate retina) is not as simple as it once seemed.
In the transfer of visual signals to the brain, the visual pathway, the retina is vertically divided in two, a temporal (nearer to the temple) half and a nasal (nearer to the nose) half. The axons from the nasal half cross the brain at the optic chiasma to join with axons from the temporal half of the other eye before passing into the lateral geniculate body.
Although there are more than 130 million retinal receptors, there are only approximately 1.2 million fibres (axons) in the optic nerve. So, a large amount of pre-processing is performed within the retina. The fovea produces the most accurate information. Despite occupying about 0.01% of the visual field (less than 2° of visual angle), about 10% of axons in the optic nerve are devoted to the fovea. The resolution limit of the fovea has been determined to be around 10,000 points. The information capacity is estimated at 500,000 bits per second (for more information on bits, see information theory) without colour or around 600,000 bits per second including colour.
When the retina sends neural impulses representing an image to the brain, it spatially encodes (compresses) those impulses to fit the limited capacity of the optic nerve. Compression is necessary because there are 100 times more photoreceptor cells than ganglion cells. This is done by "decorrelation", which is carried out by the "centre-surround structures", which are implemented by the bipolar and ganglion cells.
There are two types of centre-surround structures in the retina - on-centres and off-centres. On-centres have a positively weighted centre and a negatively weighted surround. Off-centres are just the opposite. Positive weighting is more commonly known as excitatory, and negative weighting as inhibitory.
These centre-surround structures are not physical apparent, in the sense that one cannot see them by staining samples of tissue and examining the retina's anatomy. The centre-surround structures are logical (i.e., mathematically abstract) in the sense that they depend on the connection strengths between bipolar and ganglion cells. It is believed that the connection strength between cells is caused by the number and types of ion channels embedded in the synapses between the bipolar and ganglion cells.
The centre-surround structures are mathematically equivalent to the edge detection algorithms used by computer programmers to extract or enhance the edges in a digital photograph. Thus, the retina performs operations on the image-representing impulses to enhance the edges of objects within its visual field. For example, in a picture of a dog, a cat and a car, it is the edges of these objects that contain the most information. In order for higher functions in the brain (or in a computer for that matter) to extract and classify objects such as a dog and a cat, the retina is the first step to separating out the various objects within the scene.
As an example, the following matrix is at the heart of a computer algorithm that implements edge detection. This matrix is the computer equivalent to the centre-surround structure. In this example, each box (element) within this matrix would be connected to one photoreceptor. The photoreceptor in the centre is the current receptor being processed. The centre photoreceptor is multiplied by the +1 weight factor. The surrounding photoreceptors are the "nearest neighbors" to the centre and are multiplied by the -1/8 value. The sum of all nine of these elements is finally calculated. This summation is repeated for every photoreceptor in the image by shifting left to the end of a row and then down to the next line.
The total sum of this matrix is zero, if all the inputs from the nine photoreceptors are of the same value. The zero result indicates the image was uniform (non-changing) within this small patch. Negative or positive sums mean the image was varying (changing) within this small patch of nine photoreceptors.
The above matrix is only an approximation to what really happens inside the retina. The differences are:
Here is an example of an input image and how edge detection would modify it.
Once the image is spatially encoded by the centre-surround structures, the signal is sent out along the optic nerve (via the axons of the ganglion cells) through the optic chiasm to the LGN (lateral geniculate nucleus). The exact function of the LGN is unknown at this time. The output of the LGN is then sent to the back of the brain. Specifically, the output of the LGN "radiates" out to the V1 primary visual cortex.
Simplified signal flow: Photoreceptors -> Bipolar -> Ganglion -> Chiasm -> LGN -> V1 cortex
There are many inherited and acquired diseases or disorders that may affect the retina. Some of them include:
A number of different instruments are available for the diagnosis of diseases and disorders affecting the retina. Ophthalmoscopy and fundus photography have long been used to examine the retina. Recently, adaptive optics has been used to image individual rods and cones in the living human retina, and a company based in Scotland has engineered technology that allows physicians to observe the complete retina without any discomfort to patients.
The electroretinogram is used to non-invasively measure the retina's electrical activity, which is affected by certain diseases. A relatively new technology, now becoming widely available, is optical coherence tomography (OCT). This non-invasive technique allows one to obtain a 3D volumetric or high resolution cross-sectional tomogram of the fine structures of the retina, with histologic quality. Retinal vessel analysis is a non-invasive method to examine the small arteries and veins in the retina which allows to draw conclusions about the morphology and the function of small vessels elsewhere in the human body. It has been established as a predictor of cardiovascular disease and seems to have, according to a study published in 2019, potential in the early detection of Alzheimer's disease.
Treatment depends upon the nature of the disease or disorder.
The following are commonly modalities of management for retinal disease:
Rare or uncommon methods of treatment for retinal disease
Retinal gene therapy
Gene therapy holds promise as a potential avenue to cure a wide range of retinal diseases. This involves using a non-infectious virus to shuttle a gene into a part of the retina. Recombinant adeno-associated virus (rAAV) vectors possess a number of features that render them ideally suited for retinal gene therapy, including a lack of pathogenicity, minimal immunogenicity, and the ability to transduce postmitotic cells in a stable and efficient manner. rAAV vectors are increasingly utilized for their ability to mediate efficient transduction of retinal pigment epithelium (RPE), photoreceptor cells and retinal ganglion cells. Each cell type can be specifically targeted by choosing the appropriate combination of AAV serotype, promoter, and intraocular injection site.
Several clinical trials have already reported positive results using rAAV to treat Leber's congenital amaurosis, showing that the therapy was both safe and effective. There were no serious adverse events, and patients in all three studies showed improvement in their visual function as measured by a number of methods. The methods used varied among the three trials, but included both functional methods such as visual acuity and functional mobility as well as objective measures that are less susceptible to bias, such as the pupil's ability to respond to light and improvements on functional MRI. Improvements were sustained over the long-term, with patients continuing to do well after more than 1.5 years.
The unique architecture of the retina and its relatively immune-privileged environment help this process.Tight junctions that form the blood retinal barrier separate the subretinal space from the blood supply, thus protecting it from microbes and most immune-mediated damage, and enhancing its potential to respond to vector-mediated therapies. The highly compartmentalized anatomy of the eye facilitates accurate delivery of therapeutic vector suspensions to specific tissues under direct visualization using microsurgical techniques. In the sheltered environment of the retina, AAV vectors are able to maintain high levels of transgene expression in the retinal pigmented epithelium (RPE), photoreceptors, or ganglion cells for long periods of time after a single treatment. In addition, the eye and the visual system can be routinely and easily monitored for visual function and retinal structural changes after injections with noninvasive advanced technology, such as visual acuities, contrast sensitivity, fundus auto-fluorescence (FAF), dark-adapted visual thresholds, vascular diameters, pupillometry, electroretinography (ERG), multifocal ERG and optical coherence tomography (OCT).
This strategy is effective against a number of retinal diseases that have been studied, including neovascular diseases that are features of age-related macular degeneration, diabetic retinopathy and retinopathy of prematurity. Since the regulation of vascularization in the mature retina involves a balance between endogenous positive growth factors, such as vascular endothelial growth factor (VEGF) and inhibitors of angiogenesis, such as pigment epithelium-derived factor (PEDF), rAAV-mediated expression of PEDF, angiostatin, and the soluble VEGF receptor sFlt-1, which are all antiangiogenic proteins, have been shown to reduce aberrant vessel formation in animal models. Since specific gene therapies cannot readily be used to treat a significant fraction of patients with retinal dystrophy, there is a major interest in developing a more generally applicable survival factor therapy. Neurotrophic factors have the ability to modulate neuronal growth during development to maintain existing cells and to allow recovery of injured neuronal populations in the eye. AAV encoding neurotrophic factors such as fibroblast growth factor (FGF) family members and GDNF either protected photoreceptors from apoptosis or slowed down cell death.
Organ transplantation Transplantation of retinas has been attempted, but without much success. At MIT, The University of Southern California, RWTH Aachen University, and the University of New South Wales, an "artificial retina" is under development: an implant which will bypass the photoreceptors of the retina and stimulate the attached nerve cells directly, with signals from a digital camera.
A recent University of Pennsylvania study calculated that the approximate bandwidth of human retinas is 8.75 megabits per second, whereas a guinea pig's retinal transfer rate is 875 kilobits per second.
MacLaren & Pearson and colleagues at University College London and Moorfields Eye Hospital in London, in 2006, showed that photoreceptor cells could be transplanted successfully in the mouse retina if donor cells were at a critical developmental stage. Recently Ader and colleagues in Dublin showed, using the electron microscope, that transplanted photoreceptors formed synaptic connections.
In 2012, Sebastian Seung and his laboratory at MIT launched EyeWire, an online Citizen science game where players trace neurons in the retina. The goals of the EyeWire project are to identify specific cell types within the known broad classes of retinal cells, and to map the connections between neurons in the retina, which will help to determine how vision works.


West Virginia's wildlife-management program maintains diverse and high-quality habitats for a variety of wildlife and opportunities for hunters and anglers throughout the state. More than 1.4 million acres -- eight percent of the state's total land mass -- is managed by the West Virginia DNR as part of a vast network of public-access hunting and fishing areas (this does not include the more than three million acres of public-access federal lands in the state).
Officials not only work to improve habitat on these Wildlife Management Areas, or West Virginia WMAs, such as by planting or thinning of certain trees, planting shrubs for food and cover, maintenance of food plots and development of wetland areas, they also construct roads, parking areas, trails, public shooting ranges and infrastructure to make some areas handicap accessible. Over the next 10 years, the DNR plans to create nearly two dozen handicap accessible trails on its WMAs.
In 1915, the West Virginia legislature gave the Division of Natural Resources, then known as the Game and Fish Commission, the authority to purchase land to set aside as game refuges, where no hunting would be allowed. The division started buying land in the 1920s. These properties were set aside as game refuges, although when populations eventually needed culling, these areas could have been considered public-hunting areas. Most of these areas became state parks – including Kumbrabrow, Holly River and Watoga state parks, which were originally purchased in the 1920s as wildlife refuges.
For the next several decades, officials didn't see much of a need for true public-hunting areas. Private land was readily accessible for most and federal authorities started purchasing the first tracts of the Monongahelia National Forest as early as 1911.
By the 1980s, however, deer and turkey populations were re-established throughout the state and there wasn't much need for game refuges, but a new trend emerged that put the DNR back in the real-estate market.
Bob Miles, who retired as DNR wildlife-resources chief in 1994, noticed the trend that access for hunters and anglers was becoming more restrictive. He foresaw a day when only landowners would have access to hunting and fishing. There were, of course, millions of acres of federal public-hunting land in the national forests, but those were all in the eastern highlands and difficult for people in the most populous areas of the state.
Miles thought it vital to set aside property upon which any properly-licensed person could hunt or fish. To pay for it, he created the conservation stamp, which hunters are required to purchase in addition to their licenses.
His vision was that every citizen of West Virginia should have state-managed hunting and fishing access within a two hour drive of their home. The program has exceeded his wildest expectations, most residents have at least one WMA within a half hour drive. For instance, from my home in Putnam County, there are nine WMAs within a 40-minute drive of my home. One, Amherst-Plymouth (where my son shot his first squirrel) is only 10 minutes away.


What We Knew in ’81
April 9, 2012
A lot of people really appreciated getting a look at Mike MacCracken’s 1982 (above) lecture at Sandia Labs, which gave a comprehensive overview of what was then known about climate change. Quite a lot, it turns out.(if you’ve seen it, keep going. if not, watch now. I’ll wait)
RealClimate has just posted a reminder of a similar compilation a year earlier, James Hansen’s 1981 Science piece.
Sometimes it helps to take a step back from the everyday pressures of research (falling ill helps). It was in this way we stumbled across Hansen et al (1981) (pdf). In 1981 the first author of this post was in his first year at university and the other just entered the KNMI after finishing his masters. Global warming was not yet an issue at the KNMI where the focus was much more on climate variability, which explains why the article of Hansen et al. was unnoticed at that time by the second author. It turns out to be a very interesting read.
They got 10 pages in Science, which is a lot, but in it they cover radiation balance, 1D and 3D modelling, climate sensitivity, the main feedbacks (water vapour, lapse rate, clouds, ice- and vegetation albedo); solar and volcanic forcing; the uncertainties of aerosol forcings; and ocean heat uptake. Obviously climate science was a mature field even then: the concepts and conclusions have not changed all that much. Hansen et al clearly indicate what was well known (all of which still stands today) and what was uncertain.
Next they attribute global mean temperature trend 1880-1980 to CO2, volcanic and solar forcing. Most interestingly, Fig.6 (below) gives a projection for the global mean temperature up to 2100. At a time when the northern hemisphere was cooling and the global mean temperature still below the values of the early 1940s, they confidently predicted a rise in temperature due to increasing CO2 emissions. They assume that no action will be taken before the global warming signal will be significant in the late 1990s, so the different energy-use scenarios only start diverging after that.
The first 31 years of this projection are thus relatively well-defined and can now be compared to the observations. We used the GISS Land-Ocean Index that uses SST over the oceans (the original one interpolated from island stations) and overlaid the graph from the KNMI Climate Explorer on the lower left-hand corner of their Fig.6.
Given the many uncertainties at the time, notably the role of aerosols, the agreement is very good indeed. They only underestimated the observed trend by about 30%, similar or better in magnitude than the CMIP5 models over the same period (although these tend to overestimate the trend, still mainly due to problems related to aerosols).
To conclude, a projection from 1981 for rising temperatures in a major science journal, at a time that the temperature rise was not yet obvious in the observations, has been found to agree well with the observations since then, underestimating the observed trend by about 30%, and easily beating naive predictions of no-change or a linear continuation of trends. It is also a nice example of a statement based on theory that could be falsified and up to now has withstood the test. The “global warming hypothesis” has been developed according to the principles of sound science.
- J. Hansen, D. Johnson, A. Lacis, S. Lebedeff, P. Lee, D. Rind, and G. Russell, “Climate Impact of Increasing Atmospheric Carbon Dioxide”, Science, vol. 213, 1981, pp. 957-966.DOI.


New to Experimental Economics? Let us answer a few questions...
»What is Experimental Economics
+-What Is the Economic Science Institute (ESI)?
Started as an alternate, more hands-on method to economic education, the Economic Science Institute at Chapman University is an academic center that uses the laboratory method of inquiry to study the role human institutions play in creating social rules and order, and also builds and tests market and management systems. ESI’s research spans the fields of accounting, economics, finance, information systems, engineering, psychology, neuroscience, computer science and philosophy.
+-What Is Experimental Economics?
Traditionally, economists relied heavily on mathematical abstractions to understand how people behave and how markets work. But Vernon Smith recognized that markets in natural environments are dynamic and operate in specialized institutional settings. He began laboratory work to determine if those mathematical abstractions actually described market behavior, and whether they could be tested using a scientific approach.
This method has become known as Experimental Economics and earned Smith the honor of Nobel laureate and Chapman the honor of having a distinguished institute working at the frontiers of economic science.
+-Why Use Experimental Economics in the Classroom?
One of the challenges for economics students is that classes often start with theory, dealing in abstract principles that aren’t intuitive. In our courses, students start by participating in experiments related to markets and other exchange settings before discussing the theory behind the experiment.
After an experiment is complete, students have the opportunity to observe and discuss how well their own behavior – before they had any knowledge of the theory – conforms to the economic principles being examined. Sometimes traditional economic tools do an excellent job of organizing and explaining their behavior, and sometimes they don’t. Either way, the class explores the fundamental question: why?
+-Want to Read More About Experimental Economics?
See the following resources:
- Smith, V. Economics in the Laboratory,( http://www.chapman.edu/ESI/PDFs/EconomicsInLab.pdf) Journal of Economic Perspectives 8(1), 113-131, 1994. (Web-published with permission.)
- Smith, V. Experimental Methods in Economics(http://www.chapman.edu/ESI/PDFs/ExpMethodsinEconomics.pdf), The New Palgrave: A Dictionary of Economics (http://www.dictionaryofeconomics.com/dictionary), John Eatwell, Murray Milgate, and Peter Newman, 1987 (reproduced with permission of Palgrave.)
- Smith, V. Microeconomic Systems as an Experimental Science(http://www.chapman.edu/ESI/PDFs/MicroEconSystems.pdf), American Economic Review 72(5), 923-955, 1982. (Web-published with permission.)
- Wilson, B. Eexperimental Economics and Antitrust: What Can We Learn from Laboratory Markets? Antitrust, 21(2), 54-58, 2007. (Web-published with permission.)


Federal and Arizona State Minimum Wage Laws
Many aspects of wages, including payment of minimum wage, are controlled by both federal (the Fair Labor Standards Act) and state laws. When the requirements of federal and state laws differ, employers must follow the law most beneficial to employees. Arizona’s minimum wage is higher than the federal minimum wage (which currently is $7.25), hence Arizona’s minimum wage applies to Arizona employees.
Arizona recently passed the Fair Wages and Healthy Families Act (the “the Arizona Act”) establishing a new state minimum wage each year through 2020, with annual raises thereafter based on the increase in the cost of living. As of January 1, 2018, almost without exception all employees in Arizona – whether full-time, part-time or temporary – must be paid at least $10.50 an hour for all hours worked (and more for overtime hours, which is not discussed in this article). Arizona will increase the minimum hourly rate to $11 in 2019 and to $12 in 2020. Each year after that, Arizona’s minimum wage will increase in line with cost of living increases. Although the Arizona Act also requires that every employee be allowed to accrue and then use paid sick leave for a wide range of reasons outlined in the law, this article addresses only minimum wage requirements. [Earned paid sick leave is addressed in separate articles on our website.]
An employee may not agree to work for less than Arizona’s minimum wage; the minimum wage obligation cannot be waived by any oral or written agreement, or in an employment contract. Minimum wage must be paid for all hours worked, regardless of the frequency of payment and regardless of whether the wage is paid on an hourly, salaried, commissioned, piece rate, or any other basis. If in any workweek the wages paid for the hours an employee worked are less than the applicable minimum wage, the employer must pay, in addition to sums already earned, an amount sufficient to bring the employee’s weekly wage up to the current minimum wage. An exception Arizona recognizes to the minimum wage rule is that employers may pay employees receiving tips up to $3.00 per hour less than the minimum wage, provided that the tips the employee earns in each workweek bring him/her up to at least minimum wage. Arizona employers need to be aware that in contrast to federal law, which in some limited circumstances allows a lower hourly rate to be paid to youth employees for a limited period of time (among other potential exceptions), Arizona does not distinguish between adults and minors when it comes to minimum wage.
Employers subject to Arizona’s minimum wage law must comply with notice, posting, and recordkeeping requirements. Penalties for violations of the Arizona minimum wage law can be substantial. An employer who violates the Act’s recordkeeping and posting requirements is subject to a civil penalty of at least $250 for the first violation and at least $1000 for each subsequent or willful violation. Special monitoring and inspections may also be imposed. Additionally, if an employer fails to maintain required records, the employer will be presumed to have not paid the required minimum wage (or earned paid sick time) in a disputed case. An employer has the right to rebut this presumption with evidence that the employer paid the employee the required minimum wage.
We are available to help employers craft policies to comply with state and federal wage law. If you are an employee and believe you have not been paid in compliance with this or any other state or federal law, we can help. The wage and hour attorneys at Faulkner Law Offices, PLLC have decades of experience in helping employers and employees comply with these complex laws.