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A computationally simple cross-correlation model for multiple backscattering from a continuous wave (CW) noise radar is developed and verified with theoretical analysis and brute-force time-domain simulations. Based on this cross-correlation model, a modification of an existing numerical method originally developed by Holdsworth and Reid for spaced antenna (SA) pulsed radar is used to simulate the estimated cross correlation corresponding to atmospheric backscattering using a coherent CW noise radar. Subsequently, coherent radar imaging (CRI) processing comparisons between the CW noise radar and a conventional pulsed radar are presented that verify the potential of CW noise radar for atmospheric imaging. [ABSTRACT FROM AUTHOR]

In this work, the accuracy of the Doppler beam-swinging (DBS) technique for wind measurements is studied using an imaging radar—the turbulent eddy profiler (TEP) developed by the University of Massachusetts, with data collected in summer 2003. With up to 64 independent receivers, and using coherent radar imaging (CRI), several hundred partially independent beams can be formed simultaneously within the volume defined by the transmit beam. By selecting a subset of these beams, an unprecedented number of DBS configurations with varying zenith angle, azimuth angle, and number of beams can be investigated. The angular distributions of echo power and radial velocity obtained by CRI provide a unique opportunity to validate the inherent assumption in the DBS method of homogeneity across the region defined by the beam directions. Through comparison with a reference wind field, calculated as the optimal uniform wind field derived from all CRI beams with sufficient signal-to-noise ratio (SNR), the accuracy of the wind estimates for various DBS configurations is statistically analyzed. It is shown that for a three-beam DBS configuration, although the validity of the homogeneity assumption is enhanced at smaller zenith angles, the root-mean-square (RMS) error increases because of the ill-conditioned matrix in the DBS algorithm. As expected, inhomogeneities in the wind field produce large bias for the three-beam DBS configuration for large zenith angles. An optimal zenith angle, in terms of RMS error, of approximately 9°–10° was estimated. It is further shown that RMS error can be significantly reduced by increasing the number of off-vertical beams used for the DBS processing. [ABSTRACT FROM AUTHOR]

This paper highlights recent results obtained with the Turbulent Eddy Profiler (TEP), which was developed by the University of Massachusetts. This unique 915-MHz radar has up to 64 spatially separated receiving elements, each with an independent receiver. The calibrated raw data provided by this array could be processed using sophisticated imaging algorithms to resolve the horizontal structures within each range gate. After collecting all of the closely spaced horizontal slices, the TEP radar can produce three-dimensional images of echo power, radial velocity, and spectral width. From the radial velocity measurements, it is possible to estimate the three-dimensional wind with high horizontal and vertical resolution. Given the flexibility of the TEP system, various array configurations are possible. In the present work exploitation of the flexibility of TEP is attempted to enhance the rejection of clutter from unwanted biological targets. From statistical studies, most biological clutter results from targets outside the main imaging field of view, that is, the sidelobes and grating lobes (if they exist) of the receiving beam. Because the TEP array's minimum receiver separation exceeds the spatial Nyquist sampling requirement, substantial possibilities for grating-lobe clutter exist and are observed in actual array data. When imaging over the transmit beam volume, the receiving array main lobe is scanned over a ±12.5° region. This scanning also sweeps the grating lobes over a wide angular region, virtually guaranteeing that a biological scatterer outside of the main beam will appear somewhere in the imaged volume. This paper focuses on suppressing pointlike targets in the grating-lobe regions. With a subtle change to the standard TEP array hardware configuration, it is shown via simulations and actual experimental observations (collected in June 2003) that adaptive beamforming methods can subsequently be used to significantly suppress the effects of point targets on the wind field estimates. These pointlike targets can be birds or planes with strong reflectivity. By pointlike the authors mean its appearance is a distinct point (up to the imaging resolution) in the images. The pointlike strong reflectivity signature exploits the capability of adaptive beamforming to suppress the interference using the new array configuration. It should be noted that this same array configuration does not exhibit this beneficial effect when standard Fourier beamforming is employed. [ABSTRACT FROM AUTHOR]

Background: Hormone substitution for the treatment of adrenocortical insufficiency (Addison's disease) does not adequately substitute the physiological circadian secretion of corticosteroids leading to long-term sequelae and reduced quality of life. Moreover, oral administration of corticosteroids cannot mimic the hormone peaks required in stress situations. This lack of adaptation to physical and psychological stress may lead to life-threatening Addisonian crises. Allogeneic transplantation of adrenal cortex may offer an alternative. Methods: Major histocompatibility complex (MHC) class I transgenic mice (H-2Kb) were used for the implementation of an animal model of adrenocortical transplantation. Tissue fragments or selectively isolated cell suspensions of the adrenal cortex were transplanted underneath the kidney capsule of adrenalectomized mice. Kb-transgenic murine cells as well as allogeneic adrenal cortex cells were cocultured in mixed lymphocyte cultures (MLC) in order to examine the alloimmune response. Lymphocytes from T-cell receptor transgenic mice and normal allogeneic mice respectively served as responder cells. The immune response, i.e. lymphocyte proliferation, was quantified by measuring the [[sup 3]H]thymidine uptake of responder cells. The effect of corticosteroids secreted by adrenocortical cells was antagonized by the steroid receptor antagonist Mifepristone (RU 486). Results: Without need for immunosuppressive drugs, adrenocortical grafts were demonstrated to proliferate and produce corticosteroids at physiological concentrations 20 days after transplantation. Coculture of adrenal cortical cells in MLC markedly suppressed lymphocyte proliferation. This inhibited immune response was not completely antagonized by RU 486. Conclusion: In vitro, the presence of adrenocortical cells potently suppressed allogeneic immune responses. This effect was not only due to the secretion of corticosteroids, pointing to a additional immunomodulatory pro... [ABSTRACT FROM AUTHOR]

This paper addresses the benefits and drawbacks of different configurations of three and four microphone adaptive arrays. In particular, broadside and endfire configurations of equally spaced and logarithmically spaced arrays are compared. The assessment uses arrays of simple electret microphones in actual acoustic environments. Fixed and robust adaptive approaches are compared given a single interference. Adaptive endfire configurations appear to provide 2-5 dB better average performance using the same resources (microphones, aperture, and processing complexity) than adaptive broadside implementations. This is true in all cases except for interfering signals close to (<30°) the desired signal look direction (with broadside providing 1-4 dB relative improvement). © 2000 Acoustical Society of America. [ABSTRACT FROM AUTHOR]

The problem of combining the outputs of an array of microphones as a single input for a hearing aid is investigated. Emphasis is placed on the conservative prediction of realistically achievable performance gains provided by the array over a single microphone. Performance improvement is measured as a change in the speech reception threshold (SRT) between single microphone and multimicrophone conditions. Consistent with previous work, predictions of this change in SRT using intelligibility averaged gain, I, are shown to be good. Consequently, this measure is used, along with changes in signal-to-noise ratios (SNRs), to evaluate array performance. The results presented include the effects of acoustic headshadow, small room reverberation, microphone placement uncertainty, and desired speaker location uncertainty. It is in this context that realistic predictions of speech enhancement provided by robust adaptive microphone array processors are discussed. Performance improvements are demonstrated relative to the ''best'' single microphone in the array for three types of spatial filters: Fixed, robust block processed, and robust adaptive. The performance of the robust block processed arrays is shown to be attainable with adaptive implementations. One fundamental criterion employed in robust beamformer design directly limits the amount of cancellation of the desired signal that can occur. [ABSTRACT FROM AUTHOR]

Introduction: Intense military operations during deployment or training are associated with elevations in inflammatory cytokine markers. However, the influence of an inflammatory response on military-specific skills is unclear. This study examined the association between brain-derived neurotrophic factor (BDNF), glial fibrillar acidic protein, markers of inflammation, marksmanship and cognitive function following a week of intense military field training., Methods: Twenty male soldiers (20.1±0.6 years; 1.78±0.05m; 74.1±7.9kg) from the same elite combat unit of the Israel Defense Forces volunteered to participate in this study. Soldiers completed a five-day period of intense field training including navigation of 27.8km/day with load carriages of ~50% of their body mass. Soldiers slept approximately fivehours per day and were provided with military field rations. Following the final navigational exercise, soldiers returned to their base and provided a blood sample. In addition, cognitive function assessment and both dynamic and static shooting (15 shots each) were performed following a 200 m gauntlet, in which soldiers had to use hand-to-hand combat skills to reach the shooting range., Results: Results revealed that tumour necrosis factor-α (TNF-α) concentrations were inversely correlated with dynamic shooting (r=-0.646, p=0.005). In addition, a trend (r=0.415, p=0.098) was noted between TNF-α concentrations and target engagement speed (ie, time to complete the shooting protocol). BDNF concentrations were significantly correlated with the Serial Sevens Test performance (r=0.672, p=0.012)., Conclusion: The results of this investigation indicate that elevated TNF-α concentrations and lower BDNF concentrations in soldiers following intense military training were associated with decreases in marksmanship and cognitive function, respectively., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2019. No commercial re-use. See rights and permissions. Published by BMJ.)

In this study, the advantages of Digital Signal Processing (DSP) hardware for hearing aids are investigated in the context of multiple microphone arrays. One key question in multiple microphone DSP system design remains the allocation of processing resources between the number of microphones and the number of adjustable tap weights applied to each microphone. This study addresses the appropriate distribution of these resources for currently implementable adaptive DSP systems. Comparisons are made by computer simulation that includes acoustic headshadow, reverberation effects and non-ideal microphone array hardware in a wide variety of environments. Variations in the number of interfering sources, the amount of reverberation and the microphone array configuration leads to several important conclusions. Performance improvements provided by the processors are reported as the broadband unweighted signal-to-babble ratio of pre-emphasized speech and speech-shaped babble. Results are demonstrated for both fixed and robust adaptive systems.

Blood coagulation values for normal sheep and lambs, using commercially available reagents for human coagulation, are reported. Of the domestic animal species for which coagulation values have been reported, the sheep most closely resembles those of humans. Factor VII deficiency has been found in some patients with Dubin Johnson syndrome. Sheep with the same defect were found to have no coagulation abnormality.

Alteration in activity of blood coagulation factors in dogs with acute hepatic injury caused by oral carbon tetrachloride dosing was studied. Coagulation Factors II, VII and IX were dramatically reduced within 48 hours but recovered to normal in the next five days. Because surgery is rarely performed on dogs with hepatic necrosis, the use of fresh whole blood tranfusion to improve the coagulation defect in hepatic injury was also studied. Transfusion was found to have only a temporary beneficial effect.