scholarly journals From Abbott Thayer to the present day: what have we learned about the function of countershading?

2008 ◽  
Vol 364 (1516) ◽  
pp. 519-527 ◽  
Author(s):  
Hannah M Rowland
Keyword(s):  
Empirical Work ◽  
Quantitative Measure ◽  
Convincing Evidence ◽  
Colour Pattern ◽  
Protective Effects ◽  
Empirical Testing ◽  
Background Matching ◽  
Visual Characteristics ◽  
Subjective Evidence ◽  
The Many

Of the many visual characteristics of animals, countershading (darker pigmentation on those surfaces exposed to the most lighting) is one of the most common, and paradoxically one of the least well understood. Countershading has been hypothesized to reduce the detectability of prey to visually hunting predators, and while the function of a countershaded colour pattern was proposed over 100 years ago, the field has progressed slowly; convincing evidence for the protective effects of countershading has only recently emerged. Several mechanisms have been invoked for the concealing function of countershading and are discussed in this review, but the actual mechanisms by which countershading functions to reduce attacks by predators lack firm empirical testing. While there is some subjective evidence that countershaded animals match the background on which they rest, no quantitative measure of background matching has been published for countershaded animals; I now present the first such results. Most studies also fail to consider plausible alternative explanations for the colour pattern, such as protection from UV or abrasion, and thermoregulation. This paper examines the evidence to support each of these possible explanations for countershading and discusses the need for future empirical work.

scholarly journals Food Bioactive Compounds and Emerging Techniques for Their Extraction: Polyphenols as a Case Study

Foods ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 37 ◽  
Author(s):  
José S. Câmara ◽  
Bianca R. Albuquerque ◽  
Joselin Aguiar ◽  
Rúbia C. G. Corrêa ◽  
João L. Gonçalves ◽  
...  
Keyword(s):  
Bioactive Compounds ◽  
Chemical Structure ◽  
Experimental Studies ◽  
Analytical Techniques ◽  
Convincing Evidence ◽  
Protective Effects ◽  
Extraction Techniques ◽  
Biological Impact ◽  
Preventive Effects

Experimental studies have provided convincing evidence that food bioactive compounds (FBCs) have a positive biological impact on human health, exerting protective effects against non-communicable diseases (NCD) including cancer and cardiovascular (CVDs), metabolic, and neurodegenerative disorders (NDDs). These benefits have been associated with the presence of secondary metabolites, namely polyphenols, glucosinolates, carotenoids, terpenoids, alkaloids, saponins, vitamins, and fibres, among others, derived from their antioxidant, antiatherogenic, anti-inflammatory, antimicrobial, antithrombotic, cardioprotective, and vasodilator properties. Polyphenols as one of the most abundant classes of bioactive compounds present in plant-based foods emerge as a promising approach for the development of efficacious preventive agents against NCDs with reduced side effects. The aim of this review is to present comprehensive and deep insights into the potential of polyphenols, from their chemical structure classification and biosynthesis to preventive effects on NCDs, namely cancer, CVDs, and NDDS. The challenge of polyphenols bioavailability and bioaccessibility will be explored in addition to useful industrial and environmental applications. Advanced and emerging extraction techniques will be highlighted and the high-resolution analytical techniques used for FBCs characterization, identification, and quantification will be considered.

scholarly journals Can't tell the caterpillars from the trees: countershading enhances survival in a woodland

2008 ◽  
Vol 275 (1651) ◽  
pp. 2539-2545 ◽  
Author(s):  
Hannah M Rowland ◽  
Innes C Cuthill ◽  
Ian F Harvey ◽  
Michael P Speed ◽  
Graeme D Ruxton
Keyword(s):  
Visual Cues ◽  
Field Experiments ◽  
Three Dimensional ◽  
Shape From Shading ◽  
The Body ◽  
Colour Pattern ◽  
Free Living ◽  
Background Matching ◽  
Lepidopteran Larvae ◽  
Beech Tree

Perception of the body's outline and three-dimensional shape arises from visual cues such as shading, contour, perspective and texture. When a uniformly coloured prey animal is illuminated from above by sunlight, a shadow may be cast on the body, generating a brightness contrast between the dorsal and ventral surfaces. For animals such as caterpillars, which live among flat leaves, a difference in reflectance over the body surface may degrade the degree of background matching and provide cues to shape from shading. This may make otherwise cryptic prey more conspicuous to visually hunting predators. Cryptically coloured prey are expected to match their substrate in colour, pattern and texture (though disruptive patterning is an exception), but they may also abolish self-shadowing and therefore either reduce shape cues or maintain their degree of background matching through countershading: a gradation of pigment on the body of an animal so that the surface closest to illumination is darker. In this study, we report the results from a series of field experiments where artificial prey resembling lepidopteran larvae were presented on the upper surfaces of beech tree branches so that they could be viewed by free-living birds. We demonstrate that countershading is superior to uniform coloration in terms of reducing attack by free-living predators. This result persisted even when we fixed prey to the underside of branches, simulating the resting position of many tree-living caterpillars. Our experiments provide the first demonstration, in an ecologically valid visual context, that shadowing on bodies (such as lepidopteran larvae) provides cues that visually hunting predators use to detect potential prey species, and that countershading counterbalances shadowing to enhance cryptic protection.

scholarly journals Evolutionary fine-tuning of background-matching camouflage among geographical populations in the sandy beach tiger beetle

2020 ◽  
Vol 287 (1941) ◽  
pp. 20202315
Author(s):  
Nayuta Yamamoto ◽  
Teiji Sota
Keyword(s):  
Sequence Data ◽  
Evolutionary Process ◽  
Fine Tuning ◽  
Colour Pattern ◽  
Tiger Beetle ◽  
Background Matching ◽  
Geographical Populations ◽  
Geographical Distances ◽  
The Japanese Archipelago ◽  
Colour Patterns

Background-matching camouflage is a widespread adaptation in animals; however, few studies have thoroughly examined its evolutionary process and consequences. The tiger beetle Chaetodera laetescripta exhibits pronounced variation in elytral colour pattern among sandy habitats of different colour in the Japanese Archipelago. In this study, we performed digital image analysis with avian vision modelling to demonstrate that elytral luminance, which is attributed to proportions of elytral colour components, is fine-tuned to match local backgrounds. Field predation experiments with model beetles showed that better luminance matching resulted in a lower attack rate and corresponding lower mortality. Using restriction site-associated DNA (RAD) sequence data, we analysed the dispersal and evolution of colour pattern across geographical locations. We found that sand colour matching occurred irrespective of genetic and geographical distances between populations, suggesting that locally adapted colour patterns evolved after the colonization of these habitats. Given that beetle elytral colour patterns presumably have a quantitative genetic basis, our findings demonstrate that fine-tuning of background-matching camouflage to local habitat conditions can be attained through selection by visual predators, as predicted by the earliest proponent of natural selection.

The Indispensable Value of Clinical Trials in the Modernization of Traditional Chinese Medicine: 12 Years' Experience at CUHK and Future Perspectives

2014 ◽  
Vol 42 (03) ◽  
pp. 587-604 ◽  
Author(s):  
Willmann Liang ◽  
David T. Yew ◽  
Kam Lun Hon ◽  
Chun Kwok Wong ◽  
Timothy C. Y. Kwok ◽  
...  
Keyword(s):  
Clinical Trials ◽  
Chinese Medicine ◽  
Herbal Medicines ◽  
Chinese Herbs ◽  
Protective Effects ◽  
Beneficial Effects ◽  
Artery Disease ◽  
The Many

The last decade has seen a wealth of information reporting the beneficial effects of Chinese herbal medicines. While a lot more studies were done using in vitro and in vivo research platforms, much fewer investigations were conducted according to evidence-based requirements in clinical settings. The Institute of Chinese Medicine at the Chinese University of Hong Kong (CUHK) has had the opportunity to collaborate with clinicians over the years to initiate and conduct dozens of clinical trials investigating and verifying the therapeutic values of Chinese herbs in selected disease conditions. Of the many disorders, we chose to focus on those that are known for their difficulties achieving perfect results with conventional treatment methods. Examples include non-healing ulcers, allergic conditions, degenerative diseases and cancer. Protective effects of the herbs in such chronic diseases as coronary artery disease and osteoporosis were also part of our focus. Even in healthy individuals and those recovering from chemotherapy, Chinese herbs could help with the immune system and were studied in our clinical trials as well. This paper aims to highlight the important findings from these clinical studies while at the same time, stressing the indispensable value of clinical trials in modernizing the use of Chinese herbs in present-day medicine.

Advances in SEM of Polymers

1984 ◽  
Vol 57 (3) ◽  
pp. 457-506 ◽  
Author(s):  
J. R. White ◽  
E. L. Thomas
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
High Resolution ◽  
Radiation Damage ◽  
Convincing Evidence ◽  
Conductive Coating ◽  
The Many ◽  
Scanning Electron

Abstract We hope that this review contains convincing evidence of the value of scanning electron microscopy in polymer studies. Much information has been provided by this technique which could not be obtained by any other means. We hope, too, that we have indicated the kinds of problems that are confronted when dealing with this class of materials. Charging can be a problem, but this can normally be countered by applying a conductive coating. More serious is radiation damage, which may cause image deterioration and artifact production. Sometimes this will obscure the features about which information is sought and could lead to false interpretation. Proper controls should be applied and observations made at several magnifications and several beam potentials and currents to establish the best conditions. Although we have emphasized the difficulties that may be encountered when studying polymers in the SEM, many polymers provide very easy subjects, especially if high resolution (∼ 10 nm) is not sought, and standard SEM procedures are very straightforward. We hope that the value of the technique indicated by the many successful applications to which we have referred will act as sufficient incentive to outweigh any deterrent message that might be derived from our more cautionary passages relating to the difficulties.

scholarly journals Antioxidant Supplementation in the Treatment of Neurotoxicity Induced by Platinum-Based Chemotherapeutics—A Review

2020 ◽  
Vol 21 (20) ◽  
pp. 7753
Author(s):  
Jelena S. Katanic Stankovic ◽  
Dragica Selakovic ◽  
Vladimir Mihailovic ◽  
Gvozden Rosic
Keyword(s):  
Ros Generation ◽  
Protective Effects ◽  
Therapeutic Approaches ◽  
Platinum Drug ◽  
Drug Induced ◽  
Root Cause ◽  
Antioxidant Agents ◽  
Plant Antioxidants ◽  
The Many

Cancer represents one of the most pernicious public health problems with a high mortality rate among patients worldwide. Chemotherapy is one of the major therapeutic approaches for the treatment of various malignancies. Platinum-based drugs (cisplatin, oxaliplatin, carboplatin, etc.) are highly effective chemotherapeutic drugs used for the treatment of several types of malignancies, but their application and dosage are limited by their toxic effects on various systems, including neurotoxicity. Simultaneously, researchers have tried to improve the survival rate and quality of life of cancer patients and decrease the toxicity of platinum-containing drugs by combining them with non-chemotherapy-based drugs, dietary supplements and/or antioxidants. Additionally, recent studies have shown that the root cause for the many side effects of platinum chemotherapeutics involves the production of reactive oxygen species (ROS) in naive cells. Therefore, suppression of ROS generation and their inactivation with antioxidants represents an appropriate approach for platinum drug-induced toxicities. The aim of this paper is to present an updated review of the protective effects of different antioxidant agents (vitamins, dietary antioxidants and supplements, medicaments, medicinal plants and their bioactive compounds) against the neurotoxicity induced by platinum-based chemotherapeutics. This review highlights the high potential of plant antioxidants as adjuvant strategies in chemotherapy with platinum drugs.

scholarly journals III. Studies in colour changes of fish. - Part II. —An analysis of the colour patterns of the dab. - Part III. —The action of nicotin and adrenalin in the dab. - Part IV. —The action of caffeine in the dab, and a theory of the control of colour changes in fish

1927 ◽  
Vol 215 (421-430) ◽  
pp. 177-200 ◽  
Keyword(s):  
The Body ◽  
Colour Pattern ◽  
Complete Analysis ◽  
Morphological Variations ◽  
Differential Reaction ◽  
Flat Fish ◽  
Colour Changes ◽  
Morphological Differences ◽  
Colour Patterns ◽  
The Many

In the course of investigations on the action of certain drugs on the colour of the dab, it became increasingly evident that not only should a microscopic examination be made of the results, but that apart from a complete analysis of the colour pattern of the fish, such an examination would be unintelligible. I am not aware that any such analysis has been made of so complicated a colour scheme. Abolin (see List of Papers, p. 198) has analysed the colour pattern of the minnow, and in a previous paper I have pointed out that the barring on the minnow is partly due to physiological differences and partly to morphological variations. Sumner has also given a description of the patterns on certain flat-fish, but his observations were purely macroscopic. The main problem which has presented itself in this field is this :—Do all the chromatophores on the skin expand and contract synchronously and to the same degree? In other words: Are the various colour phases and manifestations of markings due to morphological differences alone? Sumner, as the result of researches carried out on flat-fish, has come to the conclusion that the many variations of colour, pattern and shade cannot be altogether explained by the assumption of a synchronous reaction of all the chromatophores, and that there must be some differential reaction of the chromatophores situated on the markings. Hogben is opposed to this view and thinks that, as “the extent of melanophore expansion in response to the intensity of a uniform background displays a very subtle gradation, it is not unlikely that the effect of a variegated background is simply to reproduce throughout the body a state of melanophore response, which renders more or less apparent a pattern dependent wholly on the numerical distribution of the melanophores in different areas.” In the present research this problem has been approached by a study of the reactions of the dab to uniform backgrounds, to ascertain the extent of the “subtle gradation” and to supply the necessary data for the further discussion of this problem.

Electoral Systems and Policy Outcomes

2017 ◽  
Author(s):  
Stephanie J. Rickard
Keyword(s):  
Electoral Systems ◽  
Empirical Work ◽  
Electoral System ◽  
Policy Outcomes ◽  
Causal Mechanism ◽  
Electoral Institutions ◽  
Policy Effects ◽  
The Many ◽  
The Relationship ◽  
Cross National

Policies as diverse as tariffs, exchange rates, and unemployment insurance vary across democratic countries. In an attempt to explain this cross-national variation, scholars have turned to the institutions that govern countries’ elections. The institutions that regulate elections, also known as an electoral system, vary significantly across democracies. Can these varied electoral institutions explain the diversity of policies observed? This question remains unanswered. Despite a growing body of research, little consensus exists as to precisely how electoral institutions affect policy. Why is it so difficult to untangle the effects of electoral institutions on economic policy? One reason for the confusion may be the imprecise manner in which electoral institutions are often measured. Better measures of electoral systems may improve our understanding of their policy effects. Improved theories that clarify the causal mechanism(s) linking electoral systems to policy outcomes will also help to clarify the relationship between electoral systems and policies. To better understand the policy effects of electoral institutions, both theoretical and empirical work must take seriously contextual factors, such as geography, which likely mediate the effects of electoral institutions. Finally, different types of empirical evidence are needed to shed new light on the policy effects of electoral institutions. It is difficult to identify the effects of electoral systems in cross-national studies because of the many other factors that vary across countries. Examining within-country variations, such as changes in district magnitude, may provide useful new insights regarding the effects of electoral institutions on policy.

scholarly journals Sleep Paralysis and Hallucinosis

1998 ◽  
Vol 11 (2) ◽  
pp. 109-112 ◽  
Author(s):  
Gregory Stores
Keyword(s):  
Bipolar Affective Disorder ◽  
Sleep Onset ◽  
Convincing Evidence ◽  
Sleep Paralysis ◽  
Diagnostic Uncertainty ◽  
Physical Conditions ◽  
Psychotic State ◽  
Appropriate Treatment ◽  
The Many ◽  
Isolated Sleep Paralysis

Background:Sleep paralysis is one of the many conditions of which visual hallucinations can be a part but has received relatively little attention. It can be associated with other dramatic symptoms of a psychotic nature likely to cause diagnostic uncertainty.Methods and results:These points are illustrated by the case of a young man with a severe bipolar affective disorder who independently developed terrifying visual, auditory and somatic hallucinatory episodes at sleep onset, associated with a sense of evil influence and presence. The episodes were not obviously related to his psychiatric disorder. Past diagnoses included nightmares and night terrors. Review provided no convincing evidence of various other sleep disorders nor physical conditions in which hallucinatory experiences can occur. A diagnosis of predormital isolated sleep paralysis was made and appropriate treatment recommended.Conclusions:Sleep paralysis, common in the general population, can be associated with dramatic auxiliary symptoms suggestive of a psychotic state. Less common forms are either part of the narcolepsy syndrome or (rarely) they are familial in type. Interestingly, sleep paralysis (especially breathing difficulty) features prominently in the folklore of various countries.

Representing qualitative social science in computational models to aid reasoning under uncertainty: National security examples

2016 ◽  
Vol 14 (1) ◽  
pp. 57-78 ◽  
Author(s):  
Paul K Davis ◽  
Angela O’Mahony
Keyword(s):  
Social Science ◽  
Computational Modeling ◽  
National Security ◽  
Computational Models ◽  
Empirical Work ◽  
Empirical Testing ◽  
Special Issue ◽  
Reasoning Under Uncertainty ◽  
Social Science Knowledge ◽  
Qualitative Models

Representing causal social science knowledge in models is difficult: much of the best knowledge is qualitative and ambiguously conditional, unlike the knowledge in “physics models.” This paper describes a stream of RAND research that began with qualitative models providing a structured depiction of casual factors creating effects. That has subsequently been extended to an unusual kind of uncertainty sensitive computational modeling that enables exploratory reasoning and analysis. We illustrate the approach with applications to counterterrorism, detection of terrorists, and nuclear crises. We believe that the approach will complement other approaches that can reflect social science phenomena [see other papers in this special issue of JDMS] and that the approach has broad potential within and beyond the national security domain. We also believe that it has the potential to inform empirical work—encouraging a transition from the step-by-step empirical testing of simple discrete hypotheses to the testing and refinement of more comprehensive causal models.

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