Asymmetric cell division in plant development

Asymmetric cell division(ACD) is a fundamental process that generates new cell types during development in eukaryotic species.In plant development,post-embryonic organogenesis driven by ACD is universal and more important than in animals,in which organ pattern is preset during embryogenesis.Thus,plant development provides a powerful system to study molecular mechanisms underlying ACD.During the past decade,tremendous progress has been made in our understanding of the key components and mechanism...     

Basic Principles of a Psychological Analysis in the Theory of Activity

The general psychological theory of activity created by L. S. Vygotsky, A. N. Leontev, A. R. Luria, and their disciples has entered a critical phase in its development. An external sign of the advent of this phase is the increased frequency of discussions of the role of the category of activity in building the conceptual apparatus of psychology. One hears ever more insistently the idea that the category of activity is threatening to become a kind of monster, ready to devour all other psychological concepts [4,14,37,45]A.n internal sign of the advent of this critical phase in the development of the theory of activity is the discrepancy between the tremendous amount of factual material accumulated in the various special areas of psychology in which the theory of activity plays a special role and the initial principles of this theory, formulated very early, when it was just being developed. As a result, a paradox has emerged: a theory engendered by the exigencies of practice is beginning to be perceived as a theory independent of practice. A critical phase in the development of any theory, like a crisis in the development of the life of a child, means the beginning of a new stage in its existence. For such a critical phase to occur, at least the following steps are, I think, necessary. The first step is enumerating the original principles of the theory of activity. The second involves an analysis, through the prism of these original principles, of all the factual material accumulated in the special areas of psychology and in general psychology. This analysis will overcome the discrepancy between the key principles of the theory of activity and the factual material, and will also help to refine and modify those principles. Finally, the third stage is the development of prospects for basic and applied research, i.e., defining the area for the most immediate development of a psychology built on the basis of a general psychological theory of activity.     

The effect of minority status and social context on the development of depression and anxiety: a longitudinal study of Puerto Rican descent youth

Few longitudinal studies have explored to date whether minority status in disadvantaged neighborhoods conveys risk for negative mental health outcomes, and the mechanisms possibly leading to such risk. We investigated how minority status influences four developmental mental health outcomes in an ethnically homogeneous sample of Puerto Rican youth. We tested models of risk for major depressive disorder (MDD) and generalized anxiety disorder (GAD), depressive and anxiety symptoms (DAS), and psychological distress, as Puerto Rican youth (aged 5‐13 years) transitioned to early adulthood (15‐29 years) in two sites, one where they grew up as a majority (the island of Puerto Rico), and another where they were part of a minority group (South Bronx, New York). At baseline, a stratified sample of 2,491 Puerto Rican youth participated from the two sites. After baseline assessment (Wave 1), each youth participant and one caregiver were assessed annually for two years, for a total of three time points (Waves 1‐3). From April 2013 to August 2017, participants were contacted for a Wave 4 interview, and a total of 2,004 young people aged 15 to 29 years participated in the assessment (response rate adjusted for eligibility = 82.8%). Using a quasi‐experimental design, we assessed impacts of minority status on MDD, GAD, DAS and psychological distress. Via mediation analyses, we explored potential mechanisms underlying the observed relationships. Data from 1,863 Puerto Rican youth (after exclusion of those with MDD or GAD during Waves 1‐3) indicated links between minority status and higher rates of lifetime and past‐year GAD, DAS and past 30‐day psychological distress at Wave 4, and a marginal trend for MDD, even after adjustments. Childhood social support and peer relationships partially explained the differences, as did intercultural conflict, neighborhood discrimination, and unfair treatment in young adulthood. The experience of growing up as a minority, as defined by context, seemingly elevates psychiatric risks, with differences in social relationships and increased social stress as mediators of this relationship. Our findings suggest that interventions at the neighborhood context rather than at the individual level might be important levers to reduce risks for the development of mood disorders in minority youth.     

To punish or repair? Evolutionary psychology and lay intuitions about modern criminal justice

We propose that intuitions about modern mass-level criminal justice emerge from evolved mechanisms designed to operate in ancestral small-scale societies. By hypothesis, individuals confronted with a crime compute two distinct psychological magnitudes: one that reflects the crime's seriousness and another that reflects the criminal's long-term value as an associate. These magnitudes are computed based on different sets of cues and are fed into motivational mechanisms regulating different aspects of sanctioning. The seriousness variable regulates how much to react (e.g., how severely we want to punish); the variable indexing the criminal's association value regulates the more fundamental decision of how to react (i.e., whether we want to punish or repair). Using experimental designs embedded in surveys, we validate this theory across several types of crime and two countries. The evidence augments past research and suggests that the human mind contains dedicated psychological mechanisms for restoring social relationships following acts of exploitation.     

A network theory of mental disorders

In recent years, the network approach to psychopathology has been advanced as an alternative way of conceptualizing mental disorders. In this approach, mental disorders arise from direct interactions between symptoms. Although the network approach has led to many novel methodologies and substantive applications, it has not yet been fully articulated as a scientific theory of mental disorders. The present paper aims to develop such a theory, by postulating a limited set of theoretical principles regarding the structure and dynamics of symptom networks. At the heart of the theory lies the notion that symptoms of psychopathology are causally connected through myriads of biological, psychological and societal mechanisms. If these causal relations are sufficiently strong, symptoms can generate a level of feedback that renders them self‐sustaining. In this case, the network can get stuck in a disorder state. The network theory holds that this is a general feature of mental disorders, which can therefore be understood as alternative stable states of strongly connected symptom networks. This idea naturally leads to a comprehensive model of psychopathology, encompassing a common explanatory model for mental disorders, as well as novel definitions of associated concepts such as mental health, resilience, vulnerability and liability. In addition, the network theory has direct implications for how to understand diagnosis and treatment, and suggests a clear agenda for future research in psychiatry and associated disciplines.     

Relationship between Obstructive Sleep Apnea Severity and Sleep,Depression and Anxiety Symptoms in Newly-Diagnosed Patients

Obstructive sleep apnea (OSA) occurs in at least 10% of the population, and leads to higher morbidity and mortality; however, relationships between OSA severity and sleep or psychological symptoms are unclear. Existing studies include samples with wide-ranging comorbidities, so we assessed relationships between severity of OSA and common sleep and psychological disturbances in recently diagnosed OSA patients with minimal co-morbidities. We studied 49 newly diagnosed, untreated OSA patients without major co-morbidities such as mental illness, cardiovascular disease, or stroke; subjects were not using psychoactive medications or tobacco (mean ± std age: 46.8±9.1 years; apnea/hyponea index [AHI]: 32.1±20.5 events/hour; female/male: 12/37; weight <125 kg). We evaluated relationships between the AHI and daytime sleepiness (Epworth Sleepiness Scale; ESS), sleep quality (Pittsburg Sleep Quality Index; PSQI), depressive symptoms (Beck Depression Inventory-II; BDI), and anxiety symptoms (Beck Anxiety Inventory; BAI), as well as sex and body mass index (BMI). AHI was similar in females and males. Mean levels of all symptoms were above normal thresholds, but AHI was not correlated with age, ESS, PSQI, BDI, or BAI; only BMI was correlated with OSA severity. No differences in mean AHI appeared when subjects were grouped by normal versus elevated values of ESS, PSQI, BDI, or BAI. Consistent with other studies, a strong link between OSA severity and psychological symptoms did not appear in these newly diagnosed patients, suggesting that mechanisms additional to the number and frequency of hypoxic events and arousals occurring with apneas contribute to adverse health effects in OSA. OSA patients presenting with mild or moderate severity, and no major co-morbidities will not necessarily have low levels of sleep or psychological disturbances.     

Evolutionary precursors of social norms in chimpanzees: a new approach

Moral behaviour, based on social norms, is commonly regarded as a hallmark of humans. Hitherto, humans are perceived to be the only species possessing social norms and to engage in moral behaviour. There is anecdotal evidence suggesting their presence in chimpanzees, but systematic studies are lacking. Here, we examine the evolution of human social norms and their underlying psychological mechanisms. For this, we distinguish between conventions, cultural social norms and universal social norms. We aim at exploring whether chimpanzees possess evolutionary precursors of universal social norms seen in humans. Chimpanzees exhibit important preconditions for their presence and enforcement: tolerant societies, well-developed social-cognitive skills and empathetic competence. Here, we develop a theoretical framework for recognizing different functional levels of social norms and distinguish them from mere statistical behavioural regularities. Quasi social norms are found where animals behave functionally moral without having moral emotions. In proto social norms, moral emotions might be present but cannot be collectivized due to the absence of a uniquely human psychological trait, i.e. shared intentionality. Human social norms, whether they are universal or cultural, involve moral emotions and are collectivized. We will discuss behaviours in chimpanzees that represent potential evolutionary precursors of human universal social norms, with special focus on social interactions involving infants. We argue that chimpanzee infants occupy a special status within their communities and propose that tolerance towards them might represent a proto social norm. Finally, we discuss possible ways to test this theoretical framework.     

Uncovering the basis for nonideal behavior of biological molecules

The molecular origin of the nonideal behavior for concentrated binary solutions of biochemical compounds is examined. The difference between activities expressed in the molar and molal conventions can be large. Considering the range from dilute to concentrated, we show that molar activity coefficients can be represented by simple but rigorous equations involving between one and three parameters only. We derive a universal relationship interconverting the scales of molarity and molality without requiring the density of the solution. The equations are developed from first principles using a statistical thermodynamic theory of molar activity coefficients. It is shown how to express activity coefficients in different concentration scales, and the advantages and disadvantages of using certain scales are discussed and compared with the experimental data. Several classes of biochemically relevant compounds, many of which are naturally occurring osmolytes, are discussed: six saccharides (glucose, xylose, maltose, mannose, raffinose, and sucrose), four polyols (glycerol, mannitol, erythritol, and sorbitol), five amino acids (glycine, alanine, sarcosine, glycine betaine, and proline), and urea. Of the 16 solutes, 10 could be described in terms of a single parameter that is due to pure first-order effects (packing, hydration, or space limitation). The remaining six exhibit significant second-order effects (solute-solute interactions) and require two additional parameters, one typically identified with the volume occupied per solute molecule in the pure solute (crystal or liquid) and the other with a self-association constant. The activity coefficients of the osmolytes roughly display the rank order found with respect to their ability to stabilize proteins. These findings are discussed in terms of the physical principles that give rise to the activity coefficients.     

Psychological processes mediating the association between developmental trauma and specific psychotic symptoms in adults: a systematic review and meta‐analysis

Experiencing psychological trauma during childhood and/or adolescence is associated with an increased risk of psychosis in adulthood. However, we lack a clear knowledge of how developmental trauma induces vulnerability to psychotic symptoms. Understanding the psychological processes involved in this association is crucial to the development of preventive interventions and improved treatments. We sought to systematically review the literature and combine findings using meta‐analytic techniques to establish the potential roles of psychological processes in the associations between developmental trauma and specific psychotic experiences (i.e., hallucinations, delusions and paranoia). Twenty‐two studies met our inclusion criteria. We found mediating roles of dissociation, emotional dysregulation and post‐traumatic stress disorder (PTSD) symptoms (avoidance, numbing and hyperarousal) between developmental trauma and hallucinations. There was also evidence of a mediating role of negative schemata, i.e. mental constructs of meanings, between developmental trauma and delusions as well as paranoia. Many studies to date have been of poor quality, and the field is limited by mostly cross‐sectional research. Our findings suggest that there may be distinct psy­chological pathways from developmental trauma to psychotic phenomena in adulthood. Clinicians should carefully ask people with psychosis about their history of developmental trauma, and screen patients with such a history for dissociation, emotional dysregulation and PTSD symptoms. Well conducted research with prospective designs, including neurocognitive assessment, is required in order to fully understand the biopsychosocial mechanisms underlying the association between developmental trauma and psychosis.     

Bioethics: An Export Product? Reflections on Hands-On Involvement in Exploring the “External” Validity of International Bioethical Declarations

As the technosciences, including genomics, develop into a global phenomenon, the question inevitably emerges whether and to what extent bioethics can and should become a globalised phenomenon as well. Could we somehow articulate a set of core principles or values that ought to be respected worldwide and that could serve as a universal guide or blueprint for bioethical regulations for embedding biotechnologies in various countries? This article considers one universal declaration, the UNESCO Declaration on Bioethics and Human Rights (2005a). General criticisms made in a recent special issue of Developing World Bioethics are that the concepts used in the Declaration are too general and vague to generate real commitment; that the so-called universal values are not universal; and, that UNESCO should not be engaged in producing such declarations which are the domain of professional bioethicists. This article considers these and other criticisms in detail and presents an example of an event in which the Declaration was used: the request by the Republic of Sakha, in Siberia, for a UNESCO delegation to advise on the initiation of a bioethics programme. The Declaration was intended to provide an adequate “framework of principles and procedures to guide states in the formulation of their legislation, policies and other instruments in the field of bioethics” (article 2a). The Declaration was produced, and principles agreed upon, in an interactive and deliberative manner with world-wide expert participation. We argue that the key issue is not whether the general principles can be exported worldwide (in principle they can), but rather how processes of implementation and institutionalisation should take shape in different social and cultural contexts. In particular, broader publics are not routinely involved in bioethical debate and policy-making processes worldwide.     

Complementary variational principles for diffusion problems with Michaelis-Menten kinetics

The theory of complementary variational principles is used to obtain maximum and minimum principles for diffusion problems with Michaelis-Menten kinetics. In an illustrative calculation we obtain an extremely accurate variational solution in good agreement with the numerical solution of McElwain (1978).     

Adaptive pattern classification and universal recoding: I. Parallel development and coding of neural feature detectors

This paper analyses a model for the parallel development and adult coding of neural feature detectors. The model was introduced in Grossberg (1976). We show how experience can retune feature detectors to respond to a prescribed convex set of spatial patterns. In particular, the detectors automatically respond to average features chosen from the set even if the average features have never been experienced. Using this procedure, any set of arbitrary spatial patterns can be recoded, or transformed, into any other spatial patterns (universal recoding), if there are sufficiently many cells in the network's cortex. The network is built from short term memory (STM) and long term memory (LTM) mechanisms, including mechanisms of adaptation, filtering, contrast enhancement, tuning, and nonspecific arousal. These mechanisms capture some experimental properties of plasticity in the kitten visual cortex. The model also suggests a classification of adult feature detector properties in terms of a small number of functional principles. In particular, experiments on retinal dynamics, including amarcrine cell function, are suggested.Supported in part by the Advanced Research Projects Agency under ONR Contract No. N00014-76-C-0185     

Evolution of aging: individual life history trade‐offs and population heterogeneity account for mortality patterns across species

A broad range of mortality patterns has been documented across species, some even including decreasing mortality over age. Whether there exist a common denominator to explain both similarities and differences in these mortality patterns remains an open question. The disposable soma theory, an evolutionary theory of aging, proposes that universal intracellular trade‐offs between maintenance/lifespan and reproduction would drive aging across species. The disposable soma theory has provided numerous insights concerning aging processes in single individuals. Yet, which specific population mortality patterns it can lead to is still largely unexplored. In this article, we propose a model exploring the mortality patterns which emerge from an evolutionary process including only the disposable soma theory core principles. We adapt a well‐known model of genomic evolution to show that mortality curves producing a kink or mid‐life plateaus derive from a common minimal evolutionary framework. These mortality shapes qualitatively correspond to those of Drosophila melanogaster, Caenorhabditis elegans, medflies, yeasts and humans. Species evolved in silico especially differ in their population diversity of maintenance strategies, which itself emerges as an adaptation to the environment over generations. Based on this integrative framework, we also derive predictions and interpretations concerning the effects of diet changes and heat‐shock treatments on mortality patterns.     

EEG Biofeedback Treatment Improves Certain Attention and Somatic Symptoms in Fibromyalgia: A Pilot Study

Fibromyalgia (FMS) is a chronic, painful disorder often associated with measurable deficiencies in attention. Since EEG biofeedback (EEG-BF) has been used successfully to treat attention problems, we reasoned that this modality might be helpful in the treatment of attention problems in FMS. We also speculated that improvement in central nervous system (CNS) function might be accompanied by improvement in FMS somatic symptoms. We studied fifteen FMS patients with attention problems, demonstrated by visual and auditory continuous performance testing (CPT), while completing 40 or more EEG-BF sessions. Training consisted of a “SMR protocol” that augmented 12–15 Hz brainwaves (sensory motor rhythm; SMR), while simultaneously inhibiting 4–7 Hz brainwaves (theta) and 22–30 Hz brainwaves (high beta). Serial measurements of pain, fatigue, psychological distress, morning stiffness, and tenderness were also obtained. Sixty-three FMS patients who received standard medical care, but who did not receive EEG-BF, served as controls. Visual, but not auditory, attention improved significantly (P < 0.008). EEG-BF treated subjects also showed improvement in tenderness, pain and fatigue. Somatic symptoms did not change significantly in controls. Visual attention parameters and certain somatic features of FMS appear to improve with an EEG-BF SMR protocol. EEG-BF training in FMS deserves further study.     

Abnormal parietal function in conversion paresis

The etiology of medically unexplained symptoms such as conversion disorder is poorly understood. This is partly because the interpretation of neuroimaging results in conversion paresis has been complicated by the use of different control groups, tasks and statistical comparisons. The present study includes these different aspects in a single data set. In our study we included both normal controls and feigners to control for conversion paresis. We studied both movement execution and imagery, and we contrasted both within-group and between-group activation. Moreover, to reveal hemisphere-specific effects that have not been reported before, we performed these analyses using both flipped and unflipped data. This approach resulted in the identification of abnormal parietal activation which was specific for conversion paresis patients. Patients also showed reduced activity in the prefrontal cortex, supramarginal gyrus and precuneus, including hemisphere-specific activation that is lateralized in the same hemisphere, regardless of right- or left-sided paresis. We propose that these regions are candidates for an interface between psychological mechanisms and disturbed higher-order motor control. Our study presents an integrative neurophysiological view of the mechanisms that contribute to the etiology of this puzzling psychological disorder, which can be further investigated with other types of conversion symptoms.     

A Theory of Cheap Control in Embodied Systems

We present a framework for designing cheap control architectures of embodied agents. Our derivation is guided by the classical problem of universal approximation, whereby we explore the possibility of exploiting the agent’s embodiment for a new and more efficient universal approximation of behaviors generated by sensorimotor control. This embodied universal approximation is compared with the classical non-embodied universal approximation. To exemplify our approach, we present a detailed quantitative case study for policy models defined in terms of conditional restricted Boltzmann machines. In contrast to non-embodied universal approximation, which requires an exponential number of parameters, in the embodied setting we are able to generate all possible behaviors with a drastically smaller model, thus obtaining cheap universal approximation. We test and corroborate the theory experimentally with a six-legged walking machine. The experiments indicate that the controller complexity predicted by our theory is close to the minimal sufficient value, which means that the theory has direct practical implications.     

The fractal nature of nature: power laws,ecological complexity and biodiversity

Underlying the diversity of life and the complexity of ecology is order that reflects the operation of fundamental physical and biological processes. Power laws describe empirical scaling relationships that are emergent quantitative features of biodiversity. These features are patterns of structure or dynamics that are self-similar or fractal-like over many orders of magnitude. Power laws allow extrapolation and prediction over a wide range of scales. Some appear to be universal, occurring in virtually all taxa of organisms and types of environments. They offer clues to underlying mechanisms that powerfully constrain biodiversity. We describe recent progress and future prospects for understanding the mechanisms that generate these power laws, and for explaining the diversity of species and complexity of ecosystems in terms of fundamental principles of physical and biological science.     

Integral Periodization of General Psychological Development

The desire to generalize current knowledge of the phased structure of human psychological development into a unified sequence that covers various stages of the developmental process as well as its mechanisms will continue to occupy psychologists until they construct this synthetic depiction. Such a universal schema could play a role in developmental psychology similar to that of the evolutionary tree in biology or the periodic table in chemistry—the role of pointing up the gaps in our knowledge. If a general picture of development is constructed, psychologists and educational theorists would be able to see the blanks or gaps, in the cultural and educational spaces that they construct in order to support optimal ways of facilitating human development at different ages (from the standpoint of particular cultural values).     

Next-Generation Individual-Based Models Integrate Biodiversity and Ecosystems: Yes We Can,and Yes We Must

Ecosystem and community ecology have evolved along different pathways, with little overlap. However, to meet societal demands for predicting changes in ecosystem services, the functional and structural view dominating these two branches of ecology, respectively, must be integrated. Biodiversity–ecosystem function research has addressed this integration for two decades, but full integration that makes predictions relevant to practical problems is still lacking. We argue that full integration requires going, in both branches, deeper by taking into account individual organisms and the evolutionary and physico-chemical principles that drive their behavior. Individual-based models are a major tool for this integration. They have matured by using individual-level mechanism to replace the demographic thinking which dominates classical theoretical ecology. Existing individual-based ecosystem models already have proven useful both for theory and application. Still, next-generation individual-based models will increasingly use standardized and re-usable submodels to represent behaviors and mechanisms such as growth, uptake of nutrients, foraging, and home range behavior. The strategy of pattern-oriented modeling then helps make such ecosystem models structurally realistic by developing theory for individual behaviors just detailed enough to reproduce and explain patterns observed at the system level. Next-generation ecosystem scientists should include the individual-based approach in their toolkit and focus on addressing real systems because theory development and solving applied problems go hand-in-hand in individual-based ecology.     

Warming reduces metabolic rate in marine snails: adaptation to fluctuating high temperatures challenges the metabolic theory of ecology

The universal temperature-dependence model (UTD) of the metabolic theory of ecology (MTE) proposes that temperature controls mass-scaled, whole-animal resting metabolic rate according to the first principles of physics (Boltzmann kinetics). Controversy surrounds the model''s implication of a mechanistic basis for metabolism that excludes the effects of adaptive regulation, and it is unclear how this would apply to organisms that live in fringe environments and typically show considerable metabolic adaptation. We explored thermal scaling of metabolism in a rocky-shore eulittoral-fringe snail (Echinolittorina malaccana) that experiences constrained energy gain and fluctuating high temperatures (between 25°C and approximately 50°C) during prolonged emersion (weeks). In contrast to the prediction of the UTD model, metabolic rate was often negatively related to temperature over a benign range (30–40°C), the relationship depending on (i) the temperature range, (ii) the degree of metabolic depression (related to the quiescent period), and (iii) whether snails were isolated within their shells. Apparent activation energies (E) varied between 0.05 and −0.43 eV, deviating excessively from the UTD''s predicted range of between 0.6 and 0.7 eV. The lowering of metabolism when heated should improve energy conservation in a high-temperature environment and challenges both the theory''s generality and its mechanistic basis.