The COVID-19 pandemic and related restrictions led to major transit demand decline for many public transit systems in the United States. This paper is a systematic analysis of the dynamics and ...dimensions of this unprecedented decline. Using transit demand data derived from a widely used transit navigation app, we fit logistic functions to model the decline in daily demand and derive key parameters: base value, the apparent minimal level of demand and cliff and base points, representing the initial date when transit demand decline began and the final date when the decline rate attenuated. Regression analyses reveal that communities with higher proportions of essential workers, vulnerable populations (African American, Hispanic, Female, and people over 45 years old), and more coronavirus Google searches tend to maintain higher levels of minimal demand during COVID-19. Approximately half of the agencies experienced their decline before the local spread of COVID-19 likely began; most of these are in the US Midwest. Almost no transit systems finished their decline periods before local community spread. We also compare hourly demand profiles for each system before and during COVID-19 using ordinary Procrustes distance analysis. The results show substantial departures from typical weekday hourly demand profiles. Our results provide insights into public transit as an essential service during a pandemic.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Abstract
Obesity is a chronic recurring disease whose prevalence has almost tripled over the past 40 years. In individuals with obesity, there is significant increased risk of morbidity and ...mortality, along with decreased quality of life. Increased obesity prevalence results, at least partly, from the increased global food supply that provides ubiquitous access to tasty, energy-dense foods. These hedonic foods and the nonfood cues that through association become reward predictive cues activate brain appetitive control circuits that drive hyperphagia and weight gain by enhancing food-seeking, motivation, and reward. Behavioral therapy (diet and lifestyle modifications) is the recommended initial treatment for obesity, yet it often fails to achieve meaningful weight loss. Furthermore, those who lose weight regain it over time through biological regulation. The need to effectively treat the pathophysiology of obesity thus centers on biologically based approaches such as bariatric surgery and more recently developed drug therapies. This review highlights neurobiological aspects relevant to obesity causation and treatment by emphasizing the common aspects of the feeding-inhibitory effects of multiple signals. We focus on glucagon like peptide-1 receptor (GLP-1R) signaling as a promising obesity treatment target by discussing the activation of intestinal- and brain-derived GLP-1 and GLP-1R expressing central nervous system circuits resulting from normal eating, bariatric surgery, and GLP-1R agonist drug therapy. Given the increased availability of energy-dense foods and frequent encounters with cues that drive hyperphagia, this review also describes how bariatric surgery and GLP-1R agonist therapies influence food reward and the motivational drive to overeat.
The evolutionary origin of the six-layered mammalian neocortex has been controversial. New data on genes with layer-specific expression in mammalian cortex have found an expression pattern in avian ...forebrain neurons consistent with the view that ‘cortical’ cells and circuits are present in all amniotes, but with different macroarchitectures in birds versus mammals.
Mitochondria, originally of bacterial origin, are highly dynamic organelles that have evolved a symbiotic relationship within eukaryotic cells. Mitochondria undergo dynamic, stage-specific ...restructuring and redistribution during oocyte maturation and preimplantation embryo development, necessary to support key developmental events. Mitochondria also fulfil a wide range of functions beyond ATP synthesis, including the production of intracellular reactive oxygen species and calcium regulation, and are active participants in the regulation of signal transduction pathways. Communication between not only mitochondria and the nucleus, but also with other organelles, is emerging as a critical function which regulates preimplantation development. Significantly, perturbations and deficits in mitochondrial function manifest not only as reduced quality and/or poor oocyte and embryo development but contribute to post-implantation failure, long-term cell function and adult disease. A growing body of evidence indicates that altered availability of metabolic co-factors modulate the activity of epigenetic modifiers, such that oocyte and embryo mitochondrial activity and dynamics have the capacity to establish long-lasting alterations to the epigenetic landscape. It is proposed that preimplantation embryo development may represent a sensitive window during which epigenetic regulation by mitochondria is likely to have significant short- and long-term effects on embryo, and offspring, health. Hence, mitochondrial integrity, communication and metabolism are critical links between the environment, the epigenome and the regulation of embryo development.
The organization of the non-mammalian forebrain had long puzzled neurobiologists. Unlike typical mammalian brains, the telencephalon is not organized in a laminated ‘cortical’ manner, with distinct ...cortical areas dedicated to individual sensory modalities or motor functions. The two major regions of the telencephalon, the basal ventricular ridge (BVR) and the dorsal ventricular ridge (DVR), were loosely referred to as being akin to the mammalian basal ganglia. The telencephalon of non-mammalian vertebrates appears to consist of multiple ‘subcortical’ groups of cells. Analysis of the nuclear organization of the avian brain, its connections, molecular properties and physiology, and organization of its pattern of circuitry and function relative to that of mammals, collectively referred to as ‘evolutionary connectomics’, revealed that only a restricted portion of the BVR is homologous to the basal ganglia of mammals. The remaining dorsal regions of the DVR, wulst and arcopallium of the avian brain contain telencephalic inputs and outputs remarkably similar to those of the individual layers of the mammalian ‘neocortex’, hippocampus and amygdala, with instances of internuclear connections strikingly similar to those found between cortical layers and within radial ‘columns’ in the mammalian sensory and motor cortices. The molecular properties of these ‘nuclei’ in birds and reptiles are similar to those of the corresponding layers of the mammalian neocortex. The fundamental pathways and cell groups of the auditory, visual and somatosensory systems of the thalamus and telencephalon are homologous at the cellular, circuit, network and gene levels, and are of great antiquity. A proposed altered migration of these homologous neurons and circuits during development is offered as a mechanism that may account for the altered configuration of mammalian telencephalae.
The endometrium is a dynamic, repetitively cycling tissue that mediates the implantation of the blastocyst. Evaluation of this complex tissue necessitates sophisticated methods that can assess its ...functional potential. Beginning in the 1950s with simple histological endometrial “dating,” these methods have crossed into the molecular era with the use of arrays aimed at dating, functional tests that assess for proliferation and differentiation, and tests that screen for inflammatory markers. In addition to these specialized tests, histologic evaluation for pathologic conditions—such as growth disorders (i.e. polyps and hyperplasia), inflammatory lesions, and retained products of conception—are critical for a complete assessment of the patient with recurrent implantation failure. Whatever the means of testing, the goal is to reveal actionable findings that can assist in offering the best options to patients who have failed multiple transfers with high quality embryos.
This Review highlights the processing and integration performed by hindbrain nuclei, focusing on the inputs received by nucleus tractus solitarius (NTS) neurons. These inputs include vagally mediated ...gastrointestinal satiation signals, blood-borne energy-related hormonal and nutrient signals, and descending neural signals from the forebrain. We propose that NTS (and hindbrain neurons, more broadly) integrate these multiple energy status signals and issue-output commands controlling the behavioral, autonomic, and endocrine responses that collectively govern energy balance. These hindbrain-mediated controls are neuroanatomically distributed; they involve endemic hindbrain neurons and circuits, hindbrain projections to peripheral circuits, and projections to and from midbrain and forebrain nuclei.
Understanding the influence of surface properties (roughness, grooves, discrete textures/dimples) on the performance of hydrodynamically lubricated contacts has been the aim of numerous studies. A ...variety of different numerical models have been employed by many researchers in order to find optimal texturing parameters (shape, size, distribution) for best performance enhancement in terms of load carrying capacity, film thickness, friction and wear. However, the large number of different modeling techniques and complexity in the patterns make finding the optimum texture a challenging task and have led to contrary conclusions. This article outlines the research effort on surface texturing worldwide, reviews the key findings and, in particular, provides a comparative summary of different modeling techniques for fluid flow, cavitation and micro-hydrodynamic effects.
•This article facilitates the application of textures for hydrodynamic contacts.•Functions of surface textures, texture design and modeling techniques are discussed.•Textures must be designed for a given application and range of operating conditions.•Robust models allow the evaluation of texture designs prior to being manufactured.•The three major challenges in numerical modeling are discussed.
Abstract Food intake is a complex behavior that can occur or cease to occur for a multitude of reasons. Decisions about where, when, what, and how much to eat are not merely reflexive responses to ...food-relevant stimuli or to changes in energy status. Rather, feeding behavior is modulated by various contextual factors and by previous experiences. The data reviewed here support the perspective that neurons in multiple hippocampal subregions constitute an important neural substrate linking the external context, the internal context, and mnemonic and cognitive information to control both appetitive and ingestive behavior. Feeding behavior is heavily influenced by hippocampal-dependent mnemonic functions, including episodic meal-related memories and conditional learned associations between food-related stimuli and postingestive consequences. These mnemonic processes are undoubtedly influenced by both external and internal factors relating to food availability, location, and physiological energy status. The afferent and efferent neuroanatomical connectivity of the subregions of the hippocampus is reviewed with regard to the integration of visuospatial and olfactory sensory information (the external context) with endocrine and gastrointestinal interoceptive stimuli (the internal context). Also discussed are recent findings demonstrating that peripherally derived endocrine signals act on receptors in hippocampal neurons to reduce (leptin, glucagon-like peptide-1) or increase (ghrelin) food intake and learned food reward-driven responding, thereby highlighting endocrine and neuropeptidergic signaling in hippocampal neurons as a novel substrate of importance in the higher-order regulation of feeding behavior.
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