Prometheus

Author(s):  
Andrew C. Scott

It is sometimes said that humans were born of fire. While a wide range of animal species interact with fire, we appear to be the only species to have learned to tame it, and more importantly to make it. There is evidence that early humans were aware of fire and may have exploited naturally occurring fire, but only later did they control and manage it. Human interaction with fire must have proceeded through various levels, the first of which can be described as the opportunistic phase. In this phase, natural fire may have been exploited to help in hunting, for example. When, how, and why did this happen? It is widely agreed that our story begins in Africa. It is here that we see the evolution of hominins, a group of related genera that include the Australopithecines and later the genus Homo. How common would fire have been in the environments in which they lived? We already know from the study of fossil plants, as well as isotope data, that there were important changes in both the vegetation and climate over the past 10 million years. It is also during this time interval that hominins emerged from apes. Through the Oligocene and Miocene (30–8 million years ago), Africa was largely covered by tropical rainforest, where fire was present but infrequent, started both by lightning strikes and volcanic activity. As the climate began to dry and C4 grasses spread at the end of the Miocene Epoch, around 8 million years ago, habitats became more open. Fire became more frequent, and from an animal perspective would have become more visible, not just from flames but also smoke. Frequent fire in the landscape would have had many consequences for the early hominins, not just because game was more easily killed, but burned animals (naturally cooked meat) would have made a useful addition to the diet, and the new flush of growth following fire would also have attracted large herds of herbivores. Fire may have been conserved through adding fuel, including dung, which is slow burning.

2016 ◽  
Vol 3 (2) ◽  
pp. 82-93
Author(s):  
Gugulethu Shamaine Nkala ◽  
Rodreck David

Knowledge presented by Oral History (OH) is unique in that it shares the tacit perspective, thoughts, opinions and understanding of the interviewee in its primary form. While teachers, lecturers and other education specialists have at their disposal a wide range of primary, secondary and tertiary sources upon which to relate and share or impart knowledge, OH presents a rich source of information that can improve the learning and knowledge impartation experience. The uniqueness of OH is presented in the following advantages of its use: it allows one to learn about the perspectives of individuals who might not otherwise appear in the historical record; it allows one to compensate for the digital age; one can learn different kinds of information; it provides historical actors with an opportunity to tell their own stories in their own words; and it offers a rich opportunity for human interaction. This article discusses the placement of oral history in the classroom set-up by investigating its use as a source of learning material presented by the National Archives of Zimbabwe to students in the Department of Records and Archives Management at the National University of Science and Technology (NUST). Interviews and a group discussion were used to gather data from an archivist at the National Archives of Zimbabwe, lecturers and students in the Department of Records and Archives Management at NUST, respectively. These groups were approached on the usability, uniqueness and other characteristics that support this type of knowledge about OH in a tertiary learning experience. The findings indicate several qualities that reflect the richness of OH as a teaching source material in a classroom set-up. It further points to weak areas that may be addressed where the source is considered a viable strategy for knowledge sharing and learning. The researchers present a possible model that can be used to champion the use of this rich knowledge source in classroom education at this university and in similar set-ups. 


2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Birbal Singh ◽  
Gorakh Mal ◽  
Vinod Verma ◽  
Ruchi Tiwari ◽  
Muhammad Imran Khan ◽  
...  

Abstract Background The global health emergency of COVID-19 has necessitated the development of multiple therapeutic modalities including vaccinations, antivirals, anti-inflammatory, and cytoimmunotherapies, etc. COVID-19 patients suffer from damage to various organs and vascular structures, so they present multiple health crises. Mesenchymal stem cells (MSCs) are of interest to treat acute respiratory distress syndrome (ARDS) caused by SARS-CoV-2 infection. Main body Stem cell-based therapies have been verified for prospective benefits in copious preclinical and clinical studies. MSCs confer potential benefits to develop various cell types and organoids for studying virus-human interaction, drug testing, regenerative medicine, and immunomodulatory effects in COVID-19 patients. Apart from paving the ways to augment stem cell research and therapies, somatic cell nuclear transfer (SCNT) holds unique ability for a wide range of health applications such as patient-specific or isogenic cells for regenerative medicine and breeding transgenic animals for biomedical applications. Being a potent cell genome-reprogramming tool, the SCNT has increased prominence of recombinant therapeutics and cellular medicine in the current era of COVID-19. As SCNT is used to generate patient-specific stem cells, it avoids dependence on embryos to obtain stem cells. Conclusions The nuclear transfer cloning, being an ideal tool to generate cloned embryos, and the embryonic stem cells will boost drug testing and cellular medicine in COVID-19.


2021 ◽  
Author(s):  
Zhanyuan Yin ◽  
Leif Zinn-Brooks

Abstract Ball-rolling dung beetles shape a portion of dung into a ball and roll it away from the dung pile for later burial and consumption. These beetles perform dances (rotations and pauses) atop their dung balls in order to choose an initial rolling direction and to correct their rolling direction (reorient). Previous mathematical modeling showed that dung beetles can use reorientation to move away from the dung pile more efficiently. In this work, we study if reorientation can help beetles avoid competition (i.e., avoid having their dung balls captured), and if so, under what circumstances? This is investigated by implementing a model with two different type of beetles, a roller with a dung ball and a searcher which seeks to capture that dung ball. We show that reorientation can help rollers avoid searchers in a wide range of conditions, but that there are some circumstances in which rolling without reorienting can be a beetle's optimal strategy. We also show that rollers can minimize the probability that their dung ball is captured without making precise measurements of the time interval between dances or the angular deviation for dances.


2006 ◽  
Vol 21 (8) ◽  
pp. 551-562 ◽  
Author(s):  
Thomas A. Pagonis ◽  
Nikiforos V. Angelopoulos ◽  
George N. Koukoulis ◽  
Christos S. Hadjichristodoulou

AbstractObjectiveThe objective of our study was to evaluate the psychological consequences of real-world AAS use in athletes abusing such agents, in comparison with a placebo and control group of comparable athletes, while correlating the severity of abuse with the side effects observed. The hypothesis tested by the study was that the use of AAS induces a wide range of psychological side effects whose impact and emergence is dependent upon the severity of the abuse.DesignThe study includes a substantial group of AAS abusing athletes and two more groups demographically similar to the first, one composed of athletes not using any substance and a placebo group. All athletes were stratified according to the severity of AAS abuse. Psychometric instruments were applied to all athletes in specific time intervals, dependent to the AAS abusers' regimens, providing us with a final psychological profile that was to be compared to the pre-study profile. All results were comparable (within and between groups) for statistically significant differences and correlated to the severity of the abuse. Homogeneity of all groups was safeguarded by random doping controls, monitoring of drug levels and analysis of all self obtained drugs by method of liquid chromatography/mass spectrometry. All athletes were provided with a common exercise and dietary regime, so common training and nutritional conditions were achieved.MethodsWe studied a cohort of 320 body-building, amateur and recreational athletes, of whom 160 were active users of AAS (group C), 80 users administering placebo drugs (group B) and 80 not abusing any substance (Group A). Group C athletes were stratified according to AAS abuse parameters, thus providing us with three subgroups of “light, medium and heavy abuse”. Athletes of groups A and B were included in a “no abuse” subgroup. The psychometric instruments used were the Symptoms Check List-90 (SCL-90) and the Hostility and Direction of Hostility Questionnaire (HDHQ). The psychometric evaluations took place within a time interval of 13 months. Statistical analysis was performed by using the Mann–Whitney/Wilcoxon two-sample non-parametric test (Kruskal–Wallis test for two groups) for data that were not normally distributed and Linear regression analysis was used to ascertain the correlation between severity of use and escalation of side effects.ResultsThe study showed a statistically significant increase in all psychometric subscales recorded in group C, and no statistically significant difference in group C and A. There was a significant increase in the scorings of group C for all subscales of SCL-90 and HDHQ. Correlation of abuse severity and side effects showed that there was a statistical significant increase in Δ values of all SCL-90 and HDHQ subscales that escalated from light abuse to medium and heavy abuse/consumption patterns.ConclusionsThe results of the study suggest that the wide range of psychiatric side effects induced by the use of AAS is correlated to the severity of abuse and the force of these side effects intensifies as the abuse escalates.


Author(s):  
Andrew C. Scott

Fire has a bad reputation. Wildfires raging across parts of California and Australia make headlines. In the news bulletins, it is a destructive force that has to be quenched. But that is far from the whole story. Fire has a long history. In our deep past, wildfire helped shape aspects of our planet, and plants and animals have adapted to it in a variety of ways. In this book, we will follow the story of fire through time. But we begin with the present, with the fires that occur around the world today, and how satellites are changing our view of wildfire. Most of us have little or no experience of a wildfire, apart from those dramatic scenes shown on our television sets from time to time. Almost invariably, two questions are asked: who started the fire, and how quickly can it be put out? Reasonable though they seem, these two questions betray a potential misunderstanding of how fire works on our planet. We assume that the fire was started by humans, either accidentally or deliberately. This may indeed be true, but more than half of the fires started across the globe have a natural cause—mostly lightning strikes, but also other causes such as volcanic activity. Every moment of every day, a fire is burning somewhere in the world. The second assumption is that a fire should always be suppressed. But should we always be rushing to put out a vegetation fire? Wildfire is one of nature’s most frightening manifestations. Winds and storms may die down, and we can seek shelter from them, but fire can be difficult to outrun and escape. Many who are killed by wildfire have underestimated this force of nature, and even those with experience in putting out fires can find themselves cut off, and succumbing to the flames. As we shall discover, not all vegetation burns in the same way, and there are many different kinds of fire, from those burning surface vegetation to those moving through the crowns of trees. Their consequences may also be very different.


Sensors ◽  
2020 ◽  
Vol 20 (20) ◽  
pp. 5820
Author(s):  
Zhenzhou Deng ◽  
Yushan Deng ◽  
Guandong Chen

Positron emission tomography (PET) has a wide range of applications in the treatment and prevention of major diseases owing to its high sensitivity and excellent resolution. However, there is still much room for optimization in the readout circuit and fast pulse sampling to further improve the performance of the PET scanner. In this work, a LIGHTENING® PET detector using a 13 × 13 lutetium-yttrium oxyorthosilicate (LYSO) crystal array read out by a 6 × 6 silicon photomultiplier (SiPM) array was developed. A novel sampling method, referred to as the dual time interval (DTI) method, is therefore proposed to realize digital acquisition of fast scintillation pulse. A semi-cut light guide was designed, which greatly improves the resolution of the edge region of the crystal array. The obtained flood histogram shown that all the 13 × 13 crystal pixels can be clearly discriminated. The optimum operating conditions for the detector were obtained by comparing the flood histogram quality under different experimental conditions. An average energy resolution (FWHM) of 14.3% and coincidence timing resolution (FWHM) of 972 ps were measured. The experimental results demonstrated that the LIGHTENING® PET detector achieves extremely high resolution which is suitable for the development of a high performance time-of-flight PET scanner.


Ozone Therapy ◽  
2019 ◽  
Vol 4 (1) ◽  
Author(s):  
Giuseppe Vitali ◽  
Luigi Valdenassi

Ozone (O3) is a bluish-coloured gas with a characteristic odour that forms in the layers of the atmosphere, near electric shocks, sparks or lightning; the extremely high voltages reached during thunderstorms produce ozone from oxygen. The particular fresh, clean odour, the smell of spring rain is the result of the ozone reproduced by nature. Ozone comes from the Greek word ozein, which means to sense the odour of. Ozone is an essential gas for life on Earth, allowing the absorption of ultraviolet light emanating from the Sun; in fact, the ozone layer in the stratosphere protects against the harmful action of UV-B ultraviolet rays. The gas, not being stable over the long term, is therefore not produced in cylinders; it can currently be prepared through special, certified and authorised devices, which use small electric discharges to convert the oxygen into ozone. It is a molecule formed by three oxygen atoms (O3), with a negative electric charge. It has a short half-life, and will therefore decay after a certain time back to its original form: oxygen. Essentially ozone is nothing but oxygen (O2) with an extra oxygen atom, which has a high electrical charge. Ozone works according to the principle of oxidation. The oxidation mechanism follows two paths: i) Direct: contact of the molecule with the contaminant; ii) Indirect: the ozone decomposes into hydroxyl radicals, more powerful but short-lived. Both reactions occur simultaneously. When the static charged ozone molecule (O3) comes into contact with something capable of oxidising, the ozone molecule’s charge flows directly over it. This happens because ozone is very unstable and tends to change back into its original form (O2). Ozone can oxidise with all kinds of materials, but also with odours and microorganisms such as bacteria, viruses and fungi. The supplemental oxygen atom is released from the ozone molecule and binds to the other material. In the end, only the pure and stable oxygen molecule remains. Ozone is one of the strongest oxidation techniques available for oxidising solutes. The supplemental/added oxygen atom will bind (=oxidation) in a second to each component that comes into contact with ozone. It is used for a wide range of purification processes. It can be employed for disinfection in municipal wastewater and in drinking water treatment plants. However, ozone is increasingly used in the industrial sector. In the food industry, for example, it is used for disinfection, and in the textile and paper industry it is used to oxidise wastewater. The main benefit of ozone is its clean nature, because it only oxidises the materials, barely forming any by-products. Since ozone has a strong characteristic distinctive odour, even very low concentrations can be quickly perceived. This generally makes it safe to work with. Since Chlorine is still the best-known oxidising and disinfectant agent, ozone is often compared with chlorine. Unlike chlorine, antibiotics or various chlorine derivatives that have no effect, ozone acts on viruses and spores. In its sterilising action, ozone directly attacks bacteria by inducing a catalytic oxidation process on the mass of bacterial proteins, unlike chlorine which acts only through specific enzymatic poisoning of vital centres, a process which requires a longer time interval and sensitive quantity for its diffusion inside the cytoplasm. Regarding the virucidal action, it is interesting to keep in mind that with a residual ozone rate of 0.6 ppm (parts per million) and with a contact time of 2 minutes, the percentage of inactivation for bacteria and viruses present in the disinfection liquid is total. Ozone’s oxidising power is 120 times greater than that of chlorine.


Author(s):  
Christopher J. Fettweis

The study of international relations has always been multidisciplinary. Over the course of the last century, political scientists have borrowed concepts, methods, and logic from a wide range of fields—from history, psychology, economics, law, sociology, anthropology, and others—in their effort to understand why states act as they do. Few of those disciplines contributed more to the course of 20th-century international relations scholarship than geography. As the layout of the chessboard shapes the game, so do the features of the Earth provide the most basic influence upon states. That geography affects international relations is uncontroversial; what is not yet clear, however, is exactly how, under what conditions, and to what extent. After all, a board can teach only a limited amount about the nature of a game. Many theories of state behavior involve several ceteris-paribus assumptions about the setting for international interaction, even if the substantial variation in geographical endowments assures that all things will never be equal. Some states are blessed (or cursed) with a rich supply of natural resources, good ports, arable land, and temperate climate; others struggle with too little (or too much) rainfall, temperature extremes, mountain ranges or deserts, powerful neighbors, or lack of access to the sea. While the number of studies examining the effects of the constants of geography on state behavior may pale in comparison to those that focus on the variables of human interaction, international relations has not been silent about geography. What insights have come from the many investigations into the relationship between the game of international politics and the board it is played on, the surface of the Earth?


2014 ◽  
Vol 88 (4) ◽  
pp. 633-635 ◽  
Author(s):  
Imran A. Rahman ◽  
Selena Y. Smith

‘Virtual paleontology’ entails the use of computational methods to assist in the three-dimensional (3-D) visualization and analysis of fossils, and has emerged as a powerful approach for research on the history of life. Three-dimensional imaging techniques allow poorly understood or previously unknown anatomies of fossil plants, invertebrates, and vertebrates, as well as microfossils and trace fossils, to be described in much greater detail than formerly possible, and are applicable to a wide range of preservation types and specimen sizes (Table 1). These methods include non-destructive high-resolution scanning technologies such as conventional X-ray micro-tomography and synchrotron-based X-ray tomography. In addition, form and function can be rigorously investigated through quantitative analysis of computer models, for example finite-element analysis.


2017 ◽  
Vol 24 (2) ◽  
pp. 401-412 ◽  
Author(s):  
Dariusz Chaberski ◽  
Robert Frankowski ◽  
Maciej Gurski ◽  
Marek Zieliński

AbstractThe paper describes the construction, operation and test results of three most popular interpolators from a viewpoint of time-interval (TI) measurement systems consisting of many tapped-delay lines (TDLs) and registering pulses of a wide-range changeable intensity. The comparison criteria include the maximum intensity of registered time stamps (TSs), the dependency of interpolator characteristic on the registered TSs’ intensity, the need of using either two counters or a mutually-complementing pair counter-register for extending a measurement range, the need of calculating offsets between TDL inputs and the dependency of a resolution increase on the number of used TDL segments. This work also contains conclusions about a range of applications, usefulness and methods of employing each described TI interpolator. The presented experimental results bring new facts that can be used by the designers who implement precise time delays in the field-programmable gate arrays (FPGA).


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