(Press-News.org) Fast growth of the global human population has long been regarded as a major challenge that faces mankind. Presently, this challenge is becoming even more serious than before, in particular because many natural resources are estimated to deplete before the end of this century.
The increasing population pressure on agriculture and ecosystems and the environment more generally is predicted to result in worldwide food and water shortages, pollution, lack of housing, poverty and social tension. The situation is exacerbated by global climate change as considerable areas of land are predicted to be flooded and hence taken out of human's use.
It is widely believed that, unless alternative scenarios of sustainable population growth and social development are identified and implemented, mankind is likely to experience stagnation or even decline.
Population growth in time is complemented with the population dynamics in space. Population distribution over space is hugely heterogeneous for a variety of reasons, to mention the climate, the history and the economy just as a few. The spatial heterogeneity may result in significant migration flows that in turn can have a significant feedback on the local demography and the population growth.
On a smaller scale of individual countries and states, understanding of the factors affecting the population distribution in space is needed to ensure adequate development of infrastructure, transport and energy network.
Poorly informed decisions are likely to result in overcrowding and social problems in urban areas and/or lower quality of life in rural neighbourhoods. Identification of scenarios of sustainable population growth and social development on various spatial and temporal scales requires good understanding of the relevant processes and mechanisms that affect both the population growth and the population distribution. Arguably, such understanding is unlikely to be achieved without a well-developed theory and the corresponding mathematical/modelling framework.
Indeed, mathematical models of human population dynamics has a long history dating back to the seventeenth century. Over the last few decades, the need for an adequate and efficient mathematical theory of the human population dynamics has been reflected by a steady growth in the number of studies where problems of demography along with related issues of economy were considered using mathematical models, tools and techniques.
In our recent paper, we use mathematical modelling to address the phenomenon of heterogeneous spatial population distribution. Heterogeneity of geographical features (mountains, forests, rivers, etc.) and natural resources (e.g. coal, iron and copper ore) are commonly accepted as factors leading to the demographic and economic heterogeneity.
Here we ask a question: is this natural heterogeneity the only underlying cause, or can there be another and perhaps more general principle responsible for emergence of heterogeneous population distribution? In order to answer this question, we first revisit available data on the population density over a few areas in different parts of the world to show that, in all cases considered, the population distribution exhibits a clear nearly periodic spatial pattern in spite of the fact that the environmental conditions are relatively uniform. Being inspired by this finding, we then consider a novel model of coupled economic-demographic dynamics in space and time and endeavour to use it to simulate the spatial population distribution. The model consists of two coupled partial-differential equations of reaction- diffusion type.
Following a similar modelling approaches that was successfully used in ecology and biology we then show that the emergence of spatial patterns in our model appears to be possible as a result of Turing instability.
Although it is not our goal to provide any direct comparison between the real-world demographic patterns and the model properties, we regard the qualitative agreement between the model predictions and the data on the human population density as an indication that the heterogeneous population distribution observed across different countries in different continents may, at least in some cases, have been caused by endogenous rather than exogenous factors, i.e. may have appeared due to intrinsic Turing instability of the corresponding economic-demographic dynamical system.
In many countries, the population distribution over space is distinctly heterogeneous, e.g. urbanized areas with a high population density alternate with rural areas with a low population density. Apparently, spatial variation in geographical and climatic factors can play a significant role in shaping the population distribution.
Our main hypothesis in our paper is the existence of a dynamical mechanism that may lead to the formation of heterogeneous population distribution regardless of the geographical heterogeneity. In our search for the real-world examples we focus on the cases where the environment may be regarded, up to a certain spatial scale, as relatively uniform. The environmental properties that we consider here as proxies for the environmental heterogeneity are the elevation, the annual mean temperature and the annual mean precipitation.
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According to the researchers, three songs from a playlist are enough to identify the person who chose the songs. Hence, companies like YouTube and Spotify can accumulate a great deal of information about their users based only on their musical preferences.
The study was led by Dr. Ori Leshman of the Jaime and Joan Constantiner School of Education at Tel Aviv University and Dr. Ron Hirschprung of the Department of Management and Industrial Engineering at Ariel University. The study was published in the journal Telematics and Informatics.
The study included ...
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The study, published in the Journal of Allergy and Clinical Immunology, was possible because of a collaboration with the University of Pittsburgh Asthma and Environmental Lung Health Institute at UPMC and the Allegheny County Health Department, with funding from The Heinz Endowments.
"In addition to verifying that people living within a 10-mile radius of the coke works had higher rates of asthma exacerbations and use of albuterol rescue medication than those living outside the radius, we learned ...
A comprehensive study from Uppsala University demonstrates that socioeconomic deprivation modifies genetic effects on higher education and abstract reasoning. The paper illustrates how genes play a greater role in educational attainment in more socioeconomically deprived regions of the United Kingdom. The study was recently published in the American Journal of Psychiatry.
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Breast cancer diagnosis: Around 88 percent of patients survive the dangerous disease in the first five years. Work is important for getting back to normality. Researchers from the University of Bonn and the German Cancer Society investigated how satisfied former patients are with their occupational development over a period of five to six years since diagnosis. About half experienced at least one job change during the study period. Around ten percent of those affected even report involuntary changes. The researchers conclude that there is a need for long-term support measures for patients. The study is now published in the Journal of Cancer Survivorship.
Breast cancer is the most commonly occurring cancer in women. ...
Amsterdam, April 28, 2021 - Parkinson's disease (PD) is characterized by slowness of movement and tremors, which often appear asymmetrically in patients. The new model of PD described in this review article published in the Journal of Parkinson's Disease may explain these perplexing asymmetrical motor symptoms and other known variations such as different degrees of constipation and sleep disorders.
PD is a heterogenous disorder. Symptoms and the speed with which symptoms progress vary greatly among patients. In three-quarters of patients, motor symptoms initially appear in one side of the body. Some ...
In an interdisciplinary research project carried out at Tel Aviv University, researchers from the School of Plant Sciences affiliated with the George S. Wise Faculty of Life Sciences collaborated with their colleagues from the Sackler Faculty of Medicine in order to study the course of plant root growth. The plant researchers were aided by a computational model constructed by cancer researchers studying cancer cells, which they adapted for use with plant root cells.
The fascinating and groundbreaking findings: For the first time in the world, it has been demonstrated, at the resolution of a single cell, that the root grows ...
In the quantum realm, electrons can group together to behave in interesting ways. Magnetism is one of these behaviors that we see in our day-to-day life, as is the rarer phenomena of superconductivity. Intriguingly, these two behaviors are often antagonists, meaning that the existence of one of them often destroys the other. However, if these two opposite quantum states are forced to coexist artificially, an elusive state called a topological superconductor appears, which is exciting for researchers trying to make topological qubits.
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Even though more and more vaccines against the coronavirus are being administered all over the world, many countries are still battling with outbreaks and face difficulties providing help to those in need.
One of those countries is Brazil. Here, they are facing a massive second wave outbreak, many daily deaths and instances of the health care systems collapsing. In the city of Manaus things have looked exceptionally bleak from December and through to the early spring.
The city was hit so hard by the first wave in 2020 that it was actually thought to be one of the few places in the world to have reached herd immunity. An estimated 75 percent of the population in the city had been infected. But then the second wave ...
The research team led by Prof. WENG Jianping from University of Science and Technology of China (USTC) of the Chinese Academy of Sciences has implemented a comprehensive preconception-to-pregnancy management plan, namely CARNATION study, for women with type1 diabetes (T1D), to reduce the risks of adverse pregnancy outcomes and improve the pregnancy care since 2015. The study was published in Diabetes Care.
The management plan, approved by the National Health and Family Planning Commission of the People's Republic of China, is made up of the checklist for the relevant health care providers (HCPs) covering 20 items of care in different ...
Computer scientists often encounter problems relevant to real-life scenarios. For instance, "multiagent problems," a category characterized by multi-stage decision-making by multiple decision makers or "agents," has relevant applications in search-and-rescue missions, firefighting, and emergency response.
Multiagent problems are often solved using a machine learning technique known as "reinforcement learning" (RL), which concerns itself with how intelligent agents make decisions in an environment unfamiliar to them. An approach usually adopted in such an endeavor is policy iteration (PI), which starts off with a "base policy" and then improves on it to generate a "rollout policy" (with the process of generation ...
