1,330 research outputs found

    The functional organization of area V2, I: Specialization across stripes and layers

    Get PDF
    We used qualitative tests to assess the sensitivity of 1043 V2 neurons (predominantly multiunits) in anesthetised macaque monkeys to direction, length. orientation. and color of moving bar stimuli. Spectral sensitivity was additionally tested by noting ON or OFF responses to flashed stimuli of varied size and color. The location of 649 units was identified with respect to cycles of cytochrome oxidase stripes (thick-inter-thin-inter) and cortical layer. We used an initial 8-way stripe classification (4 stripes. and 4 "marginal" zones at interstripes boundaries), and a 9-way layer classification (5 standard layers (2-6), and 4 "marginal" Strata at layer boundaries). These classes were collapsed differently for particular analyses of functional distribution:. the main stripe-by-layer analysis was performed on 18 compartments (3 stripes X 6 layers), We found direction sensitivity only within thick stripes, orientation sensitivity mainly in thick stripes and interstripes. and spectral sensitivity mainly in thin stripes. Positive length summation was relatively more frequent in thick stripes and interstripes. and negative length/size summation in thin stripes. All these "majority" characteristics of stripes were most prominent in layers 3A and 3B. By contrast, "minority" characteristics (e.g. spectral sensitivity in thick stripes positive size summation in thin stripes) tended to be most frequent in the outer layers, that is, layers 2 and 6. In consequence, going by the four functions tested, the distinctions between stripes were maximal in layer 3, moderate in layer 2, and minimal in layer 6. Pooling all layers, there was some indication of asymmetry in the stripe cycle, in that thin stripe characteristics (spectral sensitivity, orientation insensitivity, and negative size summation) were also evident in the marginal zone and interstripe immediately lateral to a thin stripe, but less so medially. Within thin stripes, spectral and orientation selectivities were negatively correlated this was still more accentuated amongst the minority spectrally tuned cells of thick stripes. but absent from interstripes, where these two properties were randomly assorted. Directional and spectral sensitivities were each coupled to negative size summation. but not to each other. We conclude that these functional characteristics of stripes are consistent with segregated. specialized pathways ascending through their middle layers, whilst the outer layers. 1, 2, and 6, utilize feedback from higher areas to adopt a more integrative role

    The functional logic of corticostriatal connections

    Get PDF
    Unidirectional connections from the cortex to the matrix of the corpus striatum initiate the cortico-basal ganglia (BG)-thalamocortical loop, thought to be important in momentary action selection and in longer-term fine tuning of behavioural repertoire; a discrete set of striatal compartments, striosomes, has the complementary role of registering or anticipating reward that shapes corticostriatal plasticity. Re-entrant signals traversing the cortico-BG loop impact predominantly frontal cortices, conveyed through topographically ordered output channels; by contrast, striatal input signals originate from a far broader span of cortex, and are far more divergent in their termination. The term ‘disclosed loop’ is introduced to describe this organisation: a closed circuit that is open to outside influence at the initial stage of cortical input. The closed circuit component of corticostriatal afferents is newly dubbed ‘operative’, as it is proposed to establish the bid for action selection on the part of an incipient cortical action plan; the broader set of converging corticostriatal afferents is described as contextual. A corollary of this proposal is that every unit of the striatal volume, including the long, C-shaped tail of the caudate nucleus, should receive a mandatory component of operative input, and hence include at least one area of BG-recipient cortex amongst the sources of its corticostriatal afferents. Individual operative afferents contact twin classes of GABAergic striatal projection neuron (SPN), distinguished by their neurochemical character, and onward circuitry. This is the basis of the classic direct and indirect pathway model of the cortico-BG loop. Each pathway utilises a serial chain of inhibition, with two such links, or three, providing positive and negative feedback, respectively. Operative co-activation of direct and indirect SPNs is, therefore, pictured to simultaneously promote action, and to restrain it. The balance of this rival activity is determined by the contextual inputs, which summarise the external and internal sensory environment, and the state of ongoing behavioural priorities. Notably, the distributed sources of contextual convergence upon a striatal locus mirror the transcortical network harnessed by the origin of the operative input to that locus, thereby capturing a similar set of contingencies relevant to determining action. The disclosed loop formulation of corticostriatal and subsequent BG loop circuitry, as advanced here, refines the operating rationale of the classic model and allows the integration of more recent anatomical and physiological data, some of which can appear at variance with the classic model. Equally, it provides a lucid functional context for continuing cellular studies of SPN biophysics and mechanisms of synaptic plasticity

    A Longitudinal Study of the Establishment and Proliferation of Enterococcus on a Dairy Farm

    Get PDF
    Enterococci are Gram-positive, facultative anaerobic cocci. They are found in many environments (including milk and dairy products, vegetables, plants, cereals, and meats). Enterococci are considered commensal organisms, but can also be opportunistic pathogens associated with morbidity and mortality of humans and animals. A longitudinal study of antibiotic resistance of Enterococcus to ampicillin, erythromycin, and tetracycline was conducted on an academic teaching farm. Environmental samples were collected by drag swabs at select locations prior to and after the introduction of livestock. All samples were initially processed and screened with specialized media, and then replica plated on tryptic soy agar containing a predetermined amount of antibiotic. There was some variation in the quantity of bacterial and antibiotic-resistant colonies; however, resistance to tetracycline was extremely high. The increases of too numerous to count populations were not time-dependent and appeared consistently after the placement of cows. There is little information on the prevalence and epidemiology of antibiotic resistance of Enterococci outside of the hospital setting, including on dairy farms. Longitudinal studies are important in providing insight into the dynamics of establishment and proliferation of bacteria and of antibiotic resistance

    Physical and Biological Observations of the Northern Rim of the de Soto Canyon made from a Research Submersible

    Get PDF
    During June 1978, the research submersible DIAPHUS completed 27 dives in the north central Gulf of Mexico. Fourteen of these were concentrated on and around the high relief, northern ledge or rim of the De Soto Canyon, located at depths of 50-60 m, and approximately 25 km S of Navarre, Florida. The ledge is composed of limestone outcroppings. The invertebrate fauna is characterized as two principle assemblages, one associated with a sand-shell-coraline-algae slope and the other with a limestone block ledge. The ichthyofauna is dominated by deep water reef species, thirty of which are identified and their habitat and abundance described

    Point Count Censusing from a Submersible to Estimate Reef Fish Abundance Over Large Areas

    Get PDF
    Point count estimates of fish abundance were taken from a research submersible at thirty-two sites on a 0.5 km2 patch reef on the Florida Middle Grounds, off the West Florida Shelf. Of the fifty species recorded, nine species were selected for total population estimates based on their behavior and visibility. Data from the individual point counts were extrapolated to the entire reef. Best estimates of total populations of these species varied from 320 for the short big eye (Pristigenys alta) to 307,600 for the purple reeffish (Chromis scotti). The estimate for the commercially important red grouper (Epinephelus morio) was 1,560, a concentration reasonably similar to the 960 simultaneously estimated from a mark-recapture assessment

    Perceived Health Issues: A perspective from East-African immigrants

    Get PDF
    This Study explores Somali and Ethiopian community leaders’ perceptions about health issues in their communities and the barriers to access and utilization of primary health care services. Fourteen in-depth interviews were conducted with community leaders and thematic analysis was used to analyze interviews. Participants identified chronic diseases, the unhealthy behaviors associated with them, and mental health as major health issues. Infectious diseases were secondarily mentioned as important health concerns. Lack of insurance and limited understanding of the health system were viewed as barriers to utilizing health care services. Other identified needs were: better education within immigrant communities about major health issues, enhanced cultural awareness of health care providers, improved health care access, and assistance with the acculturation process. Recommendations to improve the communities’ health status included enhancing providers' cultural competence, educating immigrants about major health issues, and increasing mental health care access

    Understanding food consumption lifecycles using wearable cameras

    Get PDF
    Application of design in HCI is a common approach to engendering behavioural change to address important challenges such as sustainability. Encouraging such change requires an understanding of current motivations and behaviours in the domain in question. In this paper, we describe use of wearable cameras to study motivations and behaviours around food consumption by focusing on two contrasting cultures, Malaysia and the UK. Our findings highlight the potential of wearable cameras to enhance knowledge of food consumption practices and identify where and how some digital interventions might be appropriate to change food behaviour. This includes appealing to people’s motivations behind food consumption and capitalising on existing practices such as gifting of food and social meals. We propose a food consumption lifecycle as a framework to understand and design human–food interaction. The use of wearable cameras enabled us to capture a high-level overview of spatially distributed food-related practices and understand food behaviours in greater depth.This work was co-funded by Horizon Digital Economy Research Institute, UK, and Crops for the Future, Malaysia.This is the author accepted manuscript. The final version is available from Springer via http://dx.doi.org/10.1007/s00779-015-0871-

    Evaluating the High School Lunar Research Projects Program

    Get PDF
    The Center for Lunar Science and Exploration (CLSE), a collaboration between the Lunar and Planetary Institute and NASA s Johnson Space Center, is one of seven member teams of the NASA Lunar Science Institute (NLSI). In addition to research and exploration activities, the CLSE team is deeply invested in education and outreach. In support of NASA s and NLSI s objective to train the next generation of scientists, CLSE s High School Lunar Research Projects program is a conduit through which high school students can actively participate in lunar science and learn about pathways into scientific careers. The objectives of the program are to enhance 1) student views of the nature of science; 2) student attitudes toward science and science careers; and 3) student knowledge of lunar science. In its first three years, approximately 168 students and 28 teachers from across the United States have participated in the program. Before beginning their research, students undertake Moon 101, a guided-inquiry activity designed to familiarize them with lunar science and exploration. Following Moon 101, and guided by a lunar scientist mentor, teams choose a research topic, ask their own research question, and design their own research approach to direct their investigation. At the conclusion of their research, teams present their results to a panel of lunar scientists. This panel selects four posters to be presented at the annual Lunar Science Forum held at NASA Ames. The top scoring team travels to the forum to present their research in person

    Leveraging U.S. Army Administrative Data for Individual and Team Performance

    Get PDF
    The Army possesses vast amounts of administrative (archival) data about Soldiers. These data sources include screening tests, personnel action codes, training scores, global assessments, physical fitness scores, and more. However, the Army has yet to integrate these data to create a holistic operating picture. Our research focuses on repurposing Army administrative data to (1) operationalize social constructs of interest to the Army (e.g., Army Values, Warrior Ethos) and (2) model the predictive relationship between these constructs and individual (i.e., Soldier) and team (i.e., unit) performance and readiness. The goal of the project is to provide people analytics models to Army leadership for the purposes of optimizing human capital management decisions. Our talk will describe the theoretical underpinnings of our human performance model, drawing on disciplines such as social and industrial/organizational psychology, as well as our experience gaining access to and working with Army administrative data sources. Access to the archival administrative data is provided through the Army Analytics Group (AAG), Person-event Data Environment (PDE). The PDE is a business intelligence platform that has two central functions: (1) to provide a secure repository for data sources on U.S. military personnel; and (2) to provide a secure collaborative work environment where researchers can access unclassified but sensitive military data
    • …
    corecore