Harnessing the power of theta: natural manipulations of cognitive performance during hippocampal theta-contingent eyeblink conditioning

Neurobiological oscillations are regarded as essential to normal information processing, including coordination and timing of cells and assemblies within structures as well as in long feedback loops of distributed neural systems. The hippocampal theta rhythm is a 3-12 Hz oscillatory potential observed during cognitive processes ranging from spatial navigation to associative learning. The lower range, 3-7 Hz, can occur during immobility and depends upon the integrity of cholinergic forebrain systems. Several studies have shown that the amount of pre-training theta in the rabbit strongly predicts the acquisition rate of classical eyeblink conditioning and that impairment of this system substantially slows the rate of learning. Our lab has used a brain-computer interface that delivers eyeblink conditioning trials contingent upon the explicit presence or absence of hippocampal theta. A behavioral benefit of theta-contingent training has been demonstrated in both delay and trace forms of the paradigm with a two- to four-fold increase in learning speed. This behavioral effect is accompanied by enhanced amplitude and synchrony of hippocampal local field potentials, multiple-unit excitation, and single-unit response patterns that depend on theta state. Additionally, training in the presence of hippocampal theta has led to increases in the salience of tone-induced unit firing patterns in the medial prefrontal cortex, followed by persistent multi-unit activity during the trace interval. In cerebellum, rhythmicity and precise synchrony of stimulus time-locked local field potentials with those of hippocampus occur preferentially under the theta condition. Here we review these findings, integrate them into current models of hippocampal-dependent learning and suggest how improvement in our understanding of neurobiological oscillations is critical for theories of medial temporal lobe processes underlying intact and pathological learning

A Matrix Element for Chaotic Tunnelling Rates and Scarring Intensities

It is shown that tunnelling splittings in ergodic double wells and resonant widths in ergodic metastable wells can be approximated as easily-calculated matrix elements involving the wavefunction in the neighbourhood of a certain real orbit. This orbit is a continuation of the complex orbit which crosses the barrier with minimum imaginary action. The matrix element is computed by integrating across the orbit in a surface of section representation, and uses only the wavefunction in the allowed region and the stability properties of the orbit. When the real orbit is periodic, the matrix element is a natural measure of the degree of scarring of the wavefunction. This scarring measure is canonically invariant and independent of the choice of surface of section, within semiclassical error. The result can alternatively be interpretated as the autocorrelation function of the state with respect to a transfer operator which quantises a certain complex surface of section mapping. The formula provides an efficient numerical method to compute tunnelling rates while avoiding the need for the exceedingly precise diagonalisation endemic to numerical tunnelling calculations.Comment: Submitted to Annals of Physics. This work has been submitted to Academic Press for possible publicatio

Dynamics and instabilities near the glass transition: From clusters to crystals

Molecular dynamics simulation has been used to explore the evolution, kinetics, and dynamics of a liquid–glass transition in clusters and bulk matter. We demonstrate a dynamical indicator that characterizes the onset of the glass transition in clusters and is consistent with other indicators of glass transitions in bulk systems. This criterion, based on changes in chaotic behavior as measured by the largest Liapunov exponent, reveals aspects of the microscopic processes associated with the phase change from liquid to glass, and provides a connection between the thermodynamic and dynamical behavior of systems and their multidimensional potential surfaces

Predicted carcass meat yield and primal cut yields in cattle divergent in genetic merit for a terminal index

peer-reviewedSeveral studies have clearly demonstrated the favorable impact of genetic selection on increasing beef cattle performance within the farm gate. Few studies, however, have attempted to quantify the value of genetic selection to downstream sectors of the beef industry, such as the meat processing sector. The objective of the current study was to characterize detailed carcass attributes of animals divergent in genetic merit for a terminal index as well as individual measures of genetic merit for carcass weight, conformation, and fat. The data used consisted of 53,674 young bulls and steers slaughtered between the years 2010 and 2013 in multiple Irish processing plants. All animals had a genetic evaluation as well as phenotypic measures of carcass characteristics. A terminal index, based on pedigree index for calving performance, feed intake, and carcass traits, calculated from the Irish national genetic evaluations, was obtained for each animal. Animals were categorized into four terminal index groups based on genetic merit estimates derived prior to the expression of the carcass phenotype by the animal. The association between genetic merit for terminal index with predicted phenotypic carcass red meat yield, carcass fat, carcass bone, and carcass composition, as well as between genetic merit for carcass weight, conformation, and fat with predicted phenotypic carcass red meat yield and composition were all quantified using linear mixed models. A greater terminal index value was associated with, on average, heavier phenotypic weights of each wholesale cut category. A greater terminal index value was also associated with a greater weight of meat and bone, but reduced carcass fat. Relative to animals in the lowest 25% genetic merit group, animals in the highest 25% genetic merit group had, on average, a greater predicted yield of very high value cuts (4.52 kg), high value cuts (13.13 kg), medium value cuts (6.06 kg), low value cuts (13.25 kg) as well as more total meat yield (37 kg). The results from the present study clearly signify a benefit to meat processers from breeding programs for terminal characteristics; coupled with the previously documented benefits to the producer, the benefits of breeding programs across the entire food production chain are obvious

Materials for phantoms for terahertz pulsed imaging

Phantoms are commonly used in medical imaging for quality assurance, calibration, research and teaching. They may include test patterns or simulations of organs, but in either case a tissue substitute medium is an important component of the phantom. The aim of this work was to identify materials suitable for use as tissue substitutes for the relatively new medical imaging modality terahertz pulsed imaging. Samples of different concentrations of the candidate materials TX151 and napthol green dye were prepared, and measurements made of the frequency-dependent absorption coefficient (0.5 to 1.5 THz) and refractive index (0.5 to 1.0 THz). These results were compared qualitatively with measurements made in a similar way on samples of excised human tissue (skin, adipose tissue and striated muscle). Both materials would be suitable for phantoms where the dominant mechanism to be simulated is absorption (similar to ∼100 cm(-1) at 1 THz) and where simulation of the strength of reflections from boundaries is not important; for example, test patterns for spatial resolution measurements. Only TX151 had a frequency-dependent refractive index close to that of tissue, and could therefore be used to simulate the layered structure of skin, the complexity of microvasculature or to investigate frequency-dependent interference effects that have been noted in terahertz images

Management of bovine tuberculosis in Michigan wildlife: Current status and near term prospects

Surveillance and control activities for bovine tuberculosis (bTB) in free-ranging Michigan white-tailed deer (Odocoileus virginianus) have now been underway for over a decade. Significant progress has been made, lowering apparent prevalence in deer in the core area by >60%, primarily via reduction of deer densities through hunting, and restrictions on public feeding and baiting of deer. These broad strategies of the Michigan Department of Natural Resources (MDNR), implemented with the cooperation of Michigan deer hunters, halved the deer population in the bTB endemic area. However, as hunters see fewer deer, their willingness to sustain aggressive harvests has waned, and public resentment of control measures has grown. During the past four years, apparent prevalence in core area deer has held approximately steady just below 2%. After bottoming out in 2004 at an estimated 10–12 deer/km2, deer numbers have since rebounded by ∼30%. Public compliance with baiting and feeding restrictions has been variable. In general, hunters in the core area do not perceive bTB as a problem, in spite of 13 years of MDNR outreach. To date, MDNR has expended more than US$23 million on TB-related activities. Of late, a substantial portion of that funding has been diverted to support other programs which have suffered from budget shortfalls. Livestock herd breakdowns continue to occur sporadically, averaging 3–4 per year 2005 to present. In total, 46 cattle and 4 captive deer herds have been diagnosed bTB positive statewide, the majority yielding only 1 positive animal. Five cattle herds were twice infected, one thrice. Michigan Department of Agriculture (MDA) policy emphasis has shifted towards obtaining producer support for wildlife risk mitigation and farm biosecurity. Funding has proven a limiting factor, with the majority of the US$63 million spent to date devoted to whole herd testing. Nevertheless, some initiatives justify cautious optimism. Promising research to support eventual vaccination of wild deer continues. Some hunters and landowners have begun to recognize the costs of high deer densities and supplemental feeding. A peninsula-wide ban on baiting and feeding was enacted. Some cattle producers, recognizing their precarious circumstances, have begun work to change long-held prevailing opinions among their peers about farm biosecurity. Yet formidable challenges remain, and evidence suggests that eradication of bTB, if it can be achieved, will take decades, and will require greater public and political resolve than has been demonstrated thus far

Feed efficiency and carcass metrics in growing cattle

Some definitions of feed efficiency such as residual energy intake (REI) and residual gain (RG) may not truly reflect production efficiency. The energy sinks used in the derivation of the traits include metabolic live-weight; producers finishing cattle for slaughter are, however, paid on the basis of carcass weight, as opposed to live-weight. The objective of the present study was to explore alternative definitions of REI and RG which are more reflective of production efficiency, and quantify their relationship with performance, ultrasound, and carcass traits across multiple breeds and sexes of cattle. Feed intake and live-weight records were available on 5,172 growing animals, 2,187 of which also had information relating to carcass traits; all animals were fed a concentrate-based diet representative of a feedlot diet. Animal linear mixed models were used to estimate (co)variance components. Heritability estimates for all derived REI traits varied from 0.36 (REICWF; REI using carcass weight and carcass fat as energy sinks) to 0.50 (traditional REI derived with the energy sinks of both live-weight and ADG). The heritability for the RG traits varied from 0.24 to 0.34. Phenotypic correlations among all definitions of the REI traits ranged from 0.90 (REI with REICWF) to 0.99 (traditional REI with REI using metabolic preslaughter live-weight and ADG). All were different (P \u3c 0.001) from one suggesting reranking of animals when using different definitions of REI to identify efficient cattle. The derived RG traits were either weakly or not correlated (P \u3e 0.05) with the ultrasound and carcass traits. Genetic correlations between the REI traits with carcass weight, dressing difference (i.e., live-weight immediately preslaughter minus carcass weight) and dressing percentage (i.e., carcass weight divided by live-weight immediately preslaughter) implies that selection on any of the REI traits will increase carcass weight, lower the dressing difference and increase dressing percentage. Selection on REICW (REI using carcass weight as an energy sink), as opposed to traditional REI, should increase the carcass weight 2.2 times slower but reduce the dressing difference 4.3 times faster. While traditionally defined REI is informative from a research perspective, the ability to convert energy into live-weight gain does not necessarily equate to carcass gain, and as such, traits such as REICW and REICWF provide a better description of production efficiency for feedlot cattle

Biventricular adaptation to volume overload in mice with aortic regurgitation

<p>Abstract</p> <p>Background</p> <p>Aortic valve regurgitation is usually caused by impaired coaptation of the aortic valve cusps during diastole. Hypercholesterolemia produces aortic valve lipid deposition, fibrosis, and calcification in both mice and humans, which could impair coaptation of cusps. However, a link between hypercholesterolemia and aortic regurgitation has not been established in either species. The purpose of this study was to ascertain the prevalence of aortic regurgitation in hypercholesterolemic mice and to determine its impact on the left and right ventricles.</p> <p>Methods and Results</p> <p>Eighty <it>Ldlr</it>^-/-/<it>Apob</it>^100/100/<it>Mttp</it>^fl/fl/Mx1Cre^+/+("Reversa") hypercholesterolemic mice and 40 control mice were screened for aortic regurgitation (AR) with magnetic resonance imaging at age 7.5 months. The prevalence of AR was 40% in Reversa mice, with moderate or severe regurgitation (AR⁺) in 19% of mice. In control mice, AR prevalence was 13% (p = 0.004 <it>vs</it>. Reversa), and was invariably trace or mild in severity. In-depth evaluation of cardiac response to volume overload was performed in 12 AR-positive and 12 AR-negative Reversa mice. Regurgitant fraction was 0.34 ± 0.04 in AR-positive <it>vs</it>. 0.02 ± 0.01 in AR-negative (mean ± SE; p < 0.001). AR-positive mice had significantly increased left ventricular end-diastolic volume and mass and reduced ejection fraction in both ventricles. When left ventricular ejection fraction fell below 0.60 in AR-positive (<it>n </it>= 7) mice, remodeling occurred and right ventricular systolic function progressively worsened.</p> <p>Conclusion</p> <p>Hypercholesterolemia causes aortic valve regurgitation with moderate prevalence in mice. When present, aortic valve regurgitation causes volume overload and pathological remodeling of both ventricles.</p

Shockwave/Boundary-Layer Interaction Studies Performed in the NASA Langley 20-Inch Mach 6 Air Tunnel

This paper highlights results from a collaborative study performed by The University of Tennessee Space Institute (UTSI) and NASA Langley Research Center on the Shockwave/Boundary-Layer Interaction (SWBLI) generated by a cylindrical protuberance on a flat plate in a Mach 6 flow. The study was performed in the 20-Inch Mach 6 Air Tunnel at NASA Langley Research Center and consisted of two separate entries. In the first entry, simultaneous high-speed schlieren and high-speed pressure-sensitive paint (PSP) imaging which was performed for the first time in the 20-Inch Mach 6 facility at NASA Langley were performed as well as simultaneous high-speed schlieren and oil-flow imaging. In the second entry, the model configuration was modified to increase the size of the interaction region. High-speed schlieren and infrared thermography (IR) surface imaging were performed in this second entry. The goal of these tests was to characterize the SBLI in the presence of a laminar, transitional, and turbulent boundary layer using high-speed optical imaging techniques. AoA = sting angle-of-attack () dcylinder = cylinder diameter (mm) dtrip = cylindrical tripping element diameter (mm) shock = shock stand-off distance (mm) hcylinder = cylinder height (mm) htrip = cylindrical tripping element height (mm) HSS = high-speed schlieren M = freestream Mach number PSP = pressure-sensitive paint Re = freestream unit Reynolds number (m-1) SWBLI = shockwave/boundary-layer interaction plate = model plate angle () Introduction his paper highlights two experimental entries performed in the 20-Inch Mach 6 Air Blowdown Tunnel at NASA Langley Research Center in collaboration with The University of Tennessee Space Institute (UTSI). The purpose of these entries was to characterize the dynamic shockwave/boundary-layer interaction (SWBLI) between a vertical cylinder on a flat plate and laminar, transitional (XSWBLI), and turbulent (SWTBLI) boundary layers with a freestream Mach number of 6 using non-intrusive optical diagnostics. Experiments performed by Murphree et al.1,2 were among the first to specifically characterize XSWBLI induced by a vertical cylinder on a flat plate geometry using several optical measurement techniques. Recent optical studies of XSWBLI phenomenon have been performed by UTSI at Mach 2 in their low-enthalpy blow wind tunnel3-8 and by Texas A&M University and UTSI at Mach numbers of 6 and 7 in their Adjustable Contour Expansion wind tunnel.9 The experiments described in this paper were intended to complement previous studies by expanding the freestream unit Reynolds number range, Re, over which the XSWBLI phenomena has been observed. Additionally these experiments, made possible under NASAs new facility funding model under the Aeronautics Evaluation and Test Capabilities (AETC) project, promoted collaboration between university and NASA researchers. The initial entry in the 20-Inch Mach 6 Air Tunnel at NASA Langley occurred in December of 2016. Originally, testing was to occur in November of 2016 in the 31-Inch Mach 10 Air Tunnel at NASA Langley. This facility was chosen so that the XSWBLI phenomenon could be observed at much higher Mach numbers than had previously been attempted in ground test experiments. The model selected for this experiment, a 10 half-angle wedge with a sharp leading edge (described in detail in section II.B), had previously been used by Danehy et al. [10] for boundary layer transition studies using the nitric oxide planar laser-induced fluorescence (NO PLIF) flow visualization technique. In that work, it was determined that transition could be induced downstream of a single htrip = 1-mm tall, dtrip = 4-mm diameter cylindrical tripping element and that the streamwise location of the transition could be changed for a single Re by changing the model angle-of-attack (AoA) (see Fig. A3 in Ref. [10] for more details). Based on the findings of that work, a decision was made to use the wedge model with the cylindrical tripping element to trip the boundary layer flow ahead of a cylindrical protuberance in order to achieve a XSWBLI. Unfortunately, the 31-Inch Mach 10 facility had been taken offline for repairs in October of 2016 and a decision was made to move the test to the 20-Inch Mach 6 facility. Since the behavior of the boundary layer with the chosen model configuration had not been studied before in that facility and the available test time was limited, the entry was considered to be exploratory and was used to collect spatially-resolved and time-resolved flow and surface visualization data that would be used to inform a second entry. Test techniques included simultaneous high-speed schlieren (HSS) captured at 160 kHz and high-speed pressure sensitive paint captured at 10 kHz as well as oil flow visualization, captured at 750 Hz. The second entry in the 20-Inch Mach 6 facility occurred in June and July of 2017. In this follow-on test, modifications to the wind tunnel model were made based on observations made during the first entry and included removing the cylindrical tripping element, increasing the size of the cylinder used to induce the SWBLI to increase the size of the interaction while simultaneously improving spatial resolution, and using a swept ramp array, similar to that described in Ref. [11], to trip the flow to turbulence. Simultaneous HSS (captured at 140 kHz, 100 kHz, and 40 kHz) and conventional IR thermography (captured at 30 Hz) imaging were performed simultaneously in this follow-on entry. This paper is intended to serve as a summary of the work performed during these two entries, to detail lessons learned from each entry, and to highlight some of the datasets acquired. Details on the experimental setup, model configuration, and techniques used are provided. Papers providing a more rigorous analysis of data acquired during the second entry, including statistical, spectral, and modal decomposition methods, can be found in Refs. [12,13]. An entry examining XSWBLI in the 31-Inch Mach 10 Blowdown Wind Tunnel facility is currently planned for mid-to-late calendar year 2019, pending the success of facility repairs. The work performed and described in this paper and the upcoming entry in the 31-Inch Mach 10 facility at NASA Langley have been made possible by NASAs new facility funding model under the Aeronautics Evaluation and Test Capabilities (AETC) project. Wind Tunnel Facility All experiments discussed in this paper were performed in the 20-Inch Mach 6 Air Tunnel at NASA Langley Research Center. Specific details pertaining to this facility can be found in Refs. [14,15], with only a brief description of the facility provided here. For both entries, the nominal freestream unit Reynolds number was varied between 1.8106 m-1 (0.5106 ft-1) and 26.3106 m-1 (8106 ft-1). The nominal stagnation pressure was varied between 0.21 MPa and 3.33 MPa and the nominal stagnation temperature was varied between 480 K and 520 K to achieve the desired Re condition. For all runs, the nominal freestream Mach number was 6. The nearly square test section is 520.7-mm (20.5-inches) wide by 508-mm (20-inches) high. Two 431.8-mm (17-inch) diameter windows made of Corning 7940, Grade 5F schlieren-quality glass serve as the side walls of the tunnel and provide optical access for the high-speed schlieren measurements. A rectangular window made of the same material as the side windows served as the top wall of the test section and provided optical access for the high-speed PSP and oil flow measurements. For the second entry, this top window was replaced with a Zinc Selenide (ZnSe) window with an anti-reflection coating capable of passing IR wavelengths between 8m and 12m with greater than 98% transmittance. The model was sting supported by a strut attached to a hydraulic system that allows for the model pitch angle to be adjusted between -5 to +55. For the first entry, an initial pitch/pause sweep of the model AoA was performed to observe the resulting SWBLI. Ultimately, however, the sting pitch angle for this entry was fixed at +10.0 so that the angle of the top surface of the wedge relative to the streamwise axis of the tunnel (referred to herein as the plate angle, plate), was plate = 0. For the second entry, plate = 0 and plate = -13.25 were initially tested with the swept ramp array (discussed in the following section) to determine which orientation produced conditions most favorable for XSWBLI to occur based on the heating signatures observed over the top surface of the model in the IR thermography images. Based on these initial tests, plate = -13.25 was set for the remainder of the runs in the second entry. For both entries, any model changes were performed in a housing located beneath the closed test section. Prior to performing a run of the tunnel, the housing was sealed and the tunnel started. Once the appropriate freestream conditions were achieved, the model was injected into the test section using a hydraulic injection system. B. Model Geometry For all runs, a 10 half-angle (20 full-angle) wedge model with a sharp leading edge was used. The model is described in detail in Refs. [10,16]. The top surface of the sharp leading edge of the model extended 47.8 mm from its upstream-most edge to a junction with the upstream edge of a stainless steel top plate that then extended an (a) (c) (b) Fig. 1 (a) Schematic of top surface of wedge model with gas seeding insert, (b) perspective view of the model in the 20-Inch Mach 6 tunnel with centerline pressure orifices on sharp leading edge, and (c) a perspective view of the model with stainless steel (top) and SLA middle insert (bottom) during the first entry. Flow occurs from left to right

A Brief Review of Addictive Tendencies Related to Technology Use: Conceptualization, Treatment, and Future Directions

Addictive tendencies relating to technology use entail the overuse and misuse of physical and digital devices to the point of maladjustment. Such tendencies, which can arise from video game use, mobile phone use, Internet use, and media streaming/television use, have major implications regarding people’s physiological and psychological states. Although prior research helped with the conceptual and empirical understanding of technology use, these had major limitations. Such limitations included inconsistent terminology (e.g., technology use disorder versus technological addictions), a lack of standardized criteria to diagnose or recognize addictive tendencies of technology use, differences in methodology (e.g., longitudinal studies, experimental studies, case studies, correlational studies), and construct proliferation (e.g., smartphone addiction, young adult attachment to phone). In addition, little research has been conducted regarding the effectiveness of treatments (e.g., psychopharmacological treatments) for tendencies of technology use. Studies regarding treatment efficacy have primarily been limited to case studies with small sample sizes. Ultimately, it is recommended that researchers form a unified front to address these addictive tendencies through consistent theoretical models, research, and criteria