Search

Deep brain stimulation is a promising treatment for neuropsychiatric conditions such as major depression. It could be optimized by identifying neural biomarkers that trigger therapy selectively when symptom severity is elevated. We developed an approach that first used multi-day intracranial electrophysiology and focal electrical stimulation to identify a personalized symptom-specific biomarker and a treatment location where stimulation improved symptoms. We then implanted a chronic deep brain sensing and stimulation device and implemented a biomarker-driven closed-loop therapy in an individual with depression. Closed-loop therapy resulted in a rapid and sustained improvement in depression. Future work is required to determine if the results and approach of this n-of-1 study generalize to a broader population. This case report describes a biomarker-driven closed-loop therapy for depression using implanted electrodes to continually sense brain activity and automatically trigger direct brain electrical stimulation in high-depression states., Author(s): Katherine W. Scangos [sup.1] [sup.2] , Ankit N. Khambhati [sup.1] [sup.3] , Patrick M. Daly [sup.1] [sup.2] , Ghassan S. Makhoul [sup.1] [sup.2] , Leo P. Sugrue [sup.1] [sup.4] [...]

Deep brain stimulation is a promising treatment for severe depression, but lack of efficacy in randomized trials raises questions regarding anatomical targeting. We implanted multi-site intracranial electrodes in a severely depressed patient and systematically assessed the acute response to focal electrical neuromodulation. We found an elaborate repertoire of distinctive emotional responses that were rapid in onset, reproducible, and context and state dependent. Results provide proof of concept for personalized, circuit-specific medicine in psychiatry. Acute mapping of responses to focal electrical neuromodulation in a patient with treatment-resistant depression reveals distinct mood and symptom changes that are highly context dependent., Author(s): Katherine W. Scangos [sup.1] , Ghassan S. Makhoul [sup.1] , Leo P. Sugrue [sup.3] , Edward F. Chang [sup.2] , Andrew D. Krystal [sup.1] Author Affiliations: (1) Department of [...]

Polyploidy among plants is most frequent in the arctic, where glaciation cycles put selective pressures on populations by repeated fragmentation and fluctuation in climate. Polyploids should have been more fit in the novel habitats created as glaciers receded because of increased genetic material and novel gene products, which results in phenotypic plasticity and rapid adaptation. Higher ploidy is then expected to confer a broader tolerance of environmental conditions. Eutrema edwardsii R. Br. (Brassicaceae) is an arctic-alpine mustard with a near circumpolar distribution that occurs as a tetraploid, hexaploid, and octaploid. We used flow cytometry to document the distribution of polyploid cytotypes using herbarium tissue, and modeled the niche of each cytotype to test for niche differentiation. Flow cytometry revealed four cytotypes among 85 individuals. Notably, 60% of the herbarium tissue assays were successful using tissue up to 50 years old. Principle components analysis was performed on 20 climatic variables, of which, the first four axes were used as environmental variables for niche modeling. Niche models were created for tetraploid and hexaploid populations and used to calculate niche overlap (Shoener's D). Overlap between tetraploid and hexaploid models (D = 0.534) is lower than the null distribution (D = 0.681-0.944) supporting the hypothesis of niche divergence.Key words: allopolyploidy, flow cytometry, Maxent, cryptic variation, herbarium tissue.La polyploidie chez les plantes est plus frequente dans l'Arctique ou les cycles de glaciation exercent des pressions selectives sur les populations par des fragmentations et des fluctuations repetees sur le climat. Les individus polyploides devraient etre mieux adaptes aux nouveaux habitats lors de la recession des glaciers a cause d'un materiel genetique plus riche et de produits genetiques nouveaux, ce qui donne lieu a une plasticite phenotypique et une adaptation rapide. Une ploidie plus elevee est ainsi presumee conferer une tolerance plus etendue aux conditions environnementales. Eutrema edwardsii R. Br. (Brassicaceae) est une moutarde alpine arctique dont la distribution se situe pres du circumpolaire, qui se presente sous formes tetraploide, hexaploide et octaploide. Les auteurs ont utilise la cytometrie en flux pour documenter la distribution des cytotypes polyploides a partirde tissu d'herbier etils ont modelise laniche de chaque cytotype afin de tester la differenciation des niches. La cytometrie en flux a revele l'existence de quatre cytotypes parmi les 85 individus. Fait notable, 60 % des tests realises avec les tissus d'herbier etaient fructueux, meme sur des tissus ayant jusqu'a 50 ans d'age. L'analyse en composantes principales a ete realisee sur 20 variables climatiques, parmi lesquelles les quatre premiers axes ont ete utilises comme variables environnementales pour la modelisation de la niche. Des modeles de niche ont ete crees pour les populations tetraploides et hexaploides et utilises pour calculer le chevauchement des niches (indice D de Shoener). Le chevauchement entre les modeles tetraploides et hexaploides (D = 0,534) est plus faible que la distribution nulle (D = 0,681-0,944), appuyant l'hypothese de divergence des niches. [Traduit par la Redaction]Mots-cles : alloploidie, cytometrie en flux, Maxent, variation cryptique, tissu d'herbier., IntroductionPolyploidy is ubiquitous among vascular plants and is especially prevalent in the arctic where it characterizes up to 80% of plant species (Soltis and Soltis 2000; Abbott and Brochmann 2003), [...]

Author(s): Sasa Gazibegovic [1, 2]; Diana Car [1, 2]; Hao Zhang [1]; Stijn C. Balk [1]; John A. Logan [3]; Michiel W. A. de Moor [1]; Maja C. Cassidy [1]; [...]

Author(s): Hao Zhang (corresponding author) [1]; Chun-Xiao Liu [2]; Sasa Gazibegovic [3]; Di Xu [1]; John A. Logan [4]; Guanzhong Wang [1]; Nick van Loo [1]; Jouri D. S. Bommer [...]

This paper investigates the applicability of organic and inorganic thermal parameters in a range of thermal conditions, from diagenesis to epizone, and in HP LT settings within the framework of continental subduction and exhumation in the southern Apennines, where independent thermobarometric constraints are available. Two juxtaposed tectonic units, the HP--LT Lungro--Verbicaro Unit (in the hanging wall) and the non-metamorphic Pollino--Ciagola Unit (in the footwall) have been analysed. For the Lungro--Verbicaro Unit, clay mineral thermal parameters and vitrinite reflectance underestimate metamorphic conditions (constrained by petrology), suggesting that, in relatively HP units, these indicators are 'retarded' and strongly depend on P--Tevolution through time. On the other hand, the K-white mica b cell dimension provides a robust estimate of peak pressure. Fluid inclusion textures indicate a fast isothermal decompression during exhumation. Two-phase inclusions from early stage syntectonic veins were trapped after isothermal exhumation at a pressure of 0.3 GPa. For the Pollino--Ciagola Unit, the correlation of analysed parameters effectively unravels the thermal evolution, with maximum palaeotemperatures of c. 150[degrees]C. Apatite fission tracks provide details of the final stages of exhumation, indicating that both units were coherently exhumed in the Late Miocene, following the tectonic emplacement of the Lungro--Verbicaro Unit on top of the Pollino--Ciagola Unit. Supplementary material: X-ray diffraction data (whole-rock composition, quantitative analysis of the doi: 10.1144/0016-76492009-137.

Background Converging evidence suggests that immune-mediated dysfunction plays an important role in the pathogenesis of frontotemporal dementia (FTD). Although genetic studies have shown that immune-associated loci are associated with increased FTD risk, a systematic investigation of genetic overlap between immune-mediated diseases and the spectrum of FTD-related disorders has not been performed. Methods and findings Using large genome-wide association studies (GWASs) (total n = 192,886 cases and controls) and recently developed tools to quantify genetic overlap/pleiotropy, we systematically identified single nucleotide polymorphisms (SNPs) jointly associated with FTD-related disorders-namely, FTD, corticobasal degeneration (CBD), progressive supranuclear palsy (PSP), and amyotrophic lateral sclerosis (ALS)-and 1 or more immune-mediated diseases including Crohn disease, ulcerative colitis (UC), rheumatoid arthritis (RA), type 1 diabetes (T1D), celiac disease (CeD), and psoriasis. We found up to 270-fold genetic enrichment between FTD and RA, up to 160-fold genetic enrichment between FTD and UC, up to 180-fold genetic enrichment between FTD and T1D, and up to 175-fold genetic enrichment between FTD and CeD. In contrast, for CBD and PSP, only 1 of the 6 immune-mediated diseases produced genetic enrichment comparable to that seen for FTD, with up to 150-fold genetic enrichment between CBD and CeD and up to 180-fold enrichment between PSP and RA. Further, we found minimal enrichment between ALS and the immune-mediated diseases tested, with the highest levels of enrichment between ALS and RA (up to 20-fold). For FTD, at a conjunction false discovery rate < 0.05 and after excluding SNPs in linkage disequilibrium, we found that 8 of the 15 identified loci mapped to the human leukocyte antigen (HLA) region on Chromosome (Chr) 6. We also found novel candidate FTD susceptibility loci within LRRK2 (leucine rich repeat kinase 2), TBKBP1 (TBK1 binding protein 1), and PGBD5 (piggyBac transposable element derived 5). Functionally, we found that the expression of FTD-immune pleiotropic genes (particularly within the HLA region) is altered in postmortem brain tissue from patients with FTD and is enriched in microglia/macrophages compared to other central nervous system cell types. The main study limitation is that the results represent only clinically diagnosed individuals. Also, given the complex interconnectedness of the HLA region, we were not able to define the specific gene or genes on Chr 6 responsible for our pleiotropic signal. Conclusions We show immune-mediated genetic enrichment specifically in FTD, particularly within the HLA region. Our genetic results suggest that for a subset of patients, immune dysfunction may contribute to FTD risk. These findings have potential implications for clinical trials targeting immune dysfunction in patients with FTD., Author(s): Iris Broce 1,*, Celeste M. Karch 2, Natalie Wen 2, Chun C. Fan 3, Yunpeng Wang 4,5, Chin Hong Tan 1, Naomi Kouri 6, Owen A. Ross 6, Günter [...]

Factors leading to endemism, and the evolutionary implications of endemism, can be explored by studying closely related taxa with variously restricted distributions. Such a model is provided by Carex section Ceratocystis (Cyperaceae); Carex cryptolepis, Carex sp. nov., and C. lutea are North American endemics with broad, restricted, and highly restricted distributions, respectively. The prediction that levels of genetic diversity are a consequence of distribution size was tested within a phylogenetic context using population level genetic variation at 18 allozyme loci. In contrast to expectations, mean proportion of loci polymorphic, number of alleles per polymorphic locus, and expected heterozygosity were significantly greater in C. lutea than either C. cryptolepis or Carex sp. nov. Although the possibility of a shift in breeding system, past introgression, or progenitor-derivative relationships could explain the relatively high levels of variation observed in C. lutea, these were dismissed on the basis of allozyme and nuclear ribosomal sequence data. We conclude that C. lutea maintains levels of genetic diversity typical of caespitose carices despite its narrow endemism and that the low levels of genetic variation in C. cryptolepis and Carex sp. nov. are likely the result of population fluctuations during Pleistocene glacial-interglacial cycles. Key words: allozymes; Atlantic Coastal Plain; Carex cryptolepis; Carex lutea; Cyperaceae; endemism; genetic diversity; glaciation.

Ultrawideband (UWB) technology is an attractive alternative for short-range applications, e.g., wireless personal area networks. In these applications, transmit and receive antennas are very close to each other and the far-field condition assumed in most of the link budget models may not be satisfied. Under near-field conditions, variations in the link budget and pulse shape compared to the far-field can be observed. In this work, a novel line-of-sight UWB link budget model for very short distances is proposed and validated with measurements using different types of antennas. The proposed model, which takes into account all main near-field effects (i.e., phase error, antenna mismatch and reradiation between antennas) and includes frequency, antenna size and orientation as parameters, shows a good agreement with the simulations and the measurements. This model has also been applied to dispersive antennas (e.g., notch-antennas), and can be used in the design and analysis of short-range UWB communication systems. Index Terms--Link budget, near-field measurements, ultrawide-band (UWB) antenna, UWB propagation channel.

For impulse radio ultrawideband communications an 'antenna plus generator' system is co-designed and an on chip generator is integrated into the antenna. This approach does away with the need for intermediate transmission lines conventionally placed between an RF device/generator and an antenna and therefore eliminates the need for a balun, prevents excitation of the common-mode currents and allows the device to be mounted directly on the antenna. The antenna and generator are designed taking into account both impedance matching and the generator's influence on the antenna's radiation properties. The suggested approach is verified experimentally at a scaled up version of the antenna. Index Terms--Antenna feed, antenna matching, balun, impulse radio (IR), integrated circuits, ultrawideband (UWB) antenna.

In this paper, we propose a new algorithm for the enhancement of plastic-cased antipersonnel mine detection using a video-impulse ground-penetrating radar (GPR). The algorithm is implemented as a nonlinear signal processor, which searches for the presence of a reference waveform in a 1-D GPR echo return. The reference waveform represents a class of targets within a certain environment. The processor marks the presence of all responses similar to the reference waveform with a sharp monocycle. Simultaneously, responses with different waveforms, which presumably correspond to clutter, are suppressed. The reference waveform and other algorithm parameters are determined from training data sets acquired in a controlled environment. After training, the algorithm can be successfully applied at sites where soil, targets, and measurement scenarios are similar but not identical to those of the training site. The processor is integrated into an automated data processing and mine detection scheme as an additional clutter suppression step. The scheme consists of clutter suppression, synthetic aperture radar focusing, construction of a confidence map, and automated detection in it. The suggested algorithm is tested on experimental data, and its performance is compared against schemes where clutter suppression is organized by means of background removal and the cross correlation with a reference wavelet. The performance comparison is done in terms of receiver operating characteristic curves. It has been found that the suggested algorithm reduces the false alarm rate in about two and a half times in comparison to the cross-correlation-based clutter suppression. Index Terms--Ground-penetrating radar (GPR), landmine detection, waveform based.

In this paper, the development of an ultra-wideband (UWB) array-based time-domain radar sensor for near-field imaging is described. The radar sensor is designed to be used within a vehicle-mounted multisensor system for humanitarian demining. The main novelty of the radar lies in the system design with a single transmitter and multichannel receiver. Design of the UWB antenna array is also novel. The radar produces 3-D images of subsurface by 1-D mechanical scanning. The imaging capability of the radar is realized via electronic steering of the receive antenna footprint in a cross-scan direction and synthetic aperture processing in an along-scan direction. Imaging via footprint steering allows for a drastic increase in the scanning speed. Index Terms--Ground penetrating radar (GPR), landmine detection, near-field imaging, ultra-wideband (UWB) antenna array.

The median preoptic nucleus (MnPO) in the lamina terminalis receives a prominent catecholaminergic innervation from the dorsomedial and ventrolateral medulla. The present investigation used whole cell patch-clamp recordings in rat brain slice preparations to evaluate the hypothesis that presynaptic adrenoceptors could modulate GABAergic inputs to MnPO neurons. Bath applications of norepinephrine (NE; 20-50 [micro]M) induced a prolonged and reversible suppression of inhibitory postsynaptic currents (IPSCs) and reduced paired-pulse depression evoked by stimulation in the subfornical organ and organum vasculosum lamina terminalis. These events were not correlated with any observed changes in membrane conductance arising from NE activity at postsynaptic [[alpha].sub.1]- or [[alpha].sub.2]-adrenoceptors. Consistent with a role for presynaptic [[alpha].sub.2]-adrenoceptors, responses were selectively mimicked by an [[alpha].sub.2]-adrenoceptor agonist (UK-14304) and blockable with an [[alpha].sub.2]-adrenoceptor antagonist (idazoxan). Although the [[alpha].sub.1]-adrenoceptor agonist cirazoline and the [[alpha].sub.1]-adrenoceptor antagonist prazosin were without effect on these evoked IPSCs, NE was noted to increase (via [[alpha].sub.2]-adrenoceptors) or decrease (via [[alpha].sub.1]-adrenoceptors) the frequency of spontaneous and tetrodotoxin-resistant miniature IPSCs. Collectively, these observations imply that both presynaptic and postsynaptic [[alpha].sub.1]-land [[alpha].sub.2]-adrenoceptors in MnPO are capable of selective modulation of rapid GAB[A.sub.A] receptor-mediated inhibitory synaptic transmission along the lamina terminalis and therefore likely to exert a prominent influence in regulating cell excitability within the MnPO. [[alpha].sub.1]-adrenoceptors; [[alpha].sub.2]-adrenoceptors; inhibitory postsynaptic currents doi:10.1152/ajpregu.00763.2006

A dual-fed, self-diplexing planar inverted F antenna and an associated RF front-end are described. It is shown that co-design of the antenna and front-end can be used to double the operational bandwidth, without significant size or performance penalties. Indeed, the use of two feeds allows the antenna to be self-diplexing, which results in improved overall efficiency. Index Terms--Antenna, front-end, planar inverted F antenna (PIFA).

The impedance change that occurs when the user holds a mobile phone antenna is a well-known problem. This paper analyses the contributions to this change for a dual-band PIFA. In particular, the contribution of the slot is shown and a method of reducing it is proposed and analyzed. Index Terms--Antenna, impedance, interaction, planar inverted F antenna (PIFA).

The reasons behind the judgment of the US President George W. Bush's presidency in the US as the most resolutely faith-based in modern times, is explored. It is argued that such a judgment is plausible enough to merit serious consideration if it is self-evidently true only if modern times began on January 20, 1989, when George H.W. Bush succeeded Ronald Reagan.

Author(s): Jorden A. van Dam [1]; Yuli V. Nazarov [1]; Erik P. A. M. Bakkers [2]; Silvano De Franceschi [1, 3]; Leo P. Kouwenhoven (corresponding author) [1] When two superconductors [...]

The White House Conference on Families both exemplified the contested nature of 'family policy' since the late nineteenth century and inaugurated the latest phase in the venerable invocation of 'family values' as a tactic for political mobilization. In 1976 presidential candidate Jimmy Carter proposed a White House Conference on the American Family in order to shore up support among cultural conservatives, especially Roman Catholics. Four years later, after much debate within the Carter administration as well as in the country at large about what constituted a legitimate family, three sessions of a White House Conference on Families were held. Cultural moderates, feminists, gays rights activists, devout Catholics, and evangelical Protestants disagreed vehemently about policies ranging from legalized abortion to family leave. Following a long though little known tradition, women were especially active among grassroots conservatives. Ultimately conservatives mobilized much more effectively than their liberal and moderate opponents, and they quickly made restoration of family values an effective wedge issue for the new Christian right and the Republican party. In many ways, the debate over family policy in the early 21st century still echoes that of the 1970s--or the 1930s or the 1910s., On October 4, 1976, addressing a convention of the National Conference of Catholic Charities, Jimmy Carter highlighted his belief that the family was the 'cornerstone of American life,' a fact [...]

Author(s): Pablo Jarillo-Herrero (corresponding author) [1]; Jorden A. van Dam [1]; Leo P. Kouwenhoven [1] Electronic transport through nanostructures is greatly affected by the presence of superconducting leads [1, 2, [...]

A consistent strategy for the design of finite array antennas consisting of differently sized radiating elements is discussed. In view of increasing the total bandwidth of the antenna system, while maintaining a low mutual coupling between the elementary radiators, sparse subarrays, operating at adjacent frequency ranges, are interleaved on a common (shared) aperture. The sparse architectures are designed using a combinatorial method that ensures an acceptable behavior in the side-lobes region in conjunction with a narrow beamwidth. The effect of the mutual coupling between identical and differently sized elements is accurately evaluated and is accounted for in predicting the performance of each individual radiator. The concept is illustrated by designing a shared aperture antenna consisting of two interwoven subarrays that jointly cover a fractional bandwidth of 14% in the X-band. Cavity-backed, stacked-patches antennas with coaxial feeding are used as elementary radiators. Index Terms--Mode-matching methods, shared aperture, sparse array antennas.

This paper presents a radiating and balanced mode analysis of planar inverted F antennas (PIFAs) mounted on wavelength-scale printed circuit boards (PCBs). The radiating mode shows, in a direct way, the extent to which the PCB influences both radiation and bandwidth. The balanced mode shows that the shorting pin acts as an impedance transformer in combination with a parallel reactance. Importantly, it can also be used to show that slots in the PIFA top plate nominally provide series reactance when the slot opening is close to the feed. Understanding of this behavior allows bandwidth improvements to be realized. It also allows dual-band antennas to be designed in a straightforward manner. Index Terms--Antenna, balanced, planar inverted F antenna (PIFA), radiating.

In March 2003 Newsweek pronounced George W. Bush's presidency the 'most resolutely 'faith based' in modern times.' (1) This judgment is plausible enough to merit serious consideration but is self-evidently [...]

Nanoscale superconductor/semiconductor hybrid devices are assembled from indium arsenide semiconductor nanowires individually contacted by aluminum-based superconductor electrodes. Below 1 kelvin, the high transparency of the contacts gives rise to proximity-induced superconductivity. The nanowires form superconducting weak links operating as mesoscopic Josephson junctions with electrically tunable coupling. The supercurrent can be switched on/off by a gate voltage acting on the electron density in the nanowire. A variation in gate voltage induces universal fluctuations in the normal-state conductance, which are clearly correlated to critical current fluctuations. The alternating-current Josephson effect gives rise to Shapiro steps in the voltage-current characteristic under microwave irradiation., The recent interest in chemically grown semiconductor nanowires arises from their versatility, which translates into a wide range of potential applications. Many important proofs of concept have already been provided, [...]

In this paper, the basic design of an adaptive ground penetrating radar antenna is introduced. The antenna is able to adapt its input impedance to a variation in the antenna elevation and soil type to keep reflections at the antenna's terminal minimum. As a result, energy transfer from the generator to the antenna is maximized, which in turn maximizes the energy radiated by the antenna into the ground for different antenna elevations and soil types. The antenna is based on a wire bow-tie structure with variable flare angle for adjusting the antenna's input impedance. The flare angle variation is realized by short-circuiting the gaps separating the wires from the feed point of the antenna, for which electronic switching devices such as PIN diodes could be used to allow fast and convenient control of the antenna's flare angle. Index Terms--Adaptive antenna, bow-tie antenna, ground penetrating radar (GPR) antenna, wire antenna.

Author(s): Pablo Jarillo-Herrero (corresponding author) [1]; Jing Kong [1, 2]; Herre S.J. van der Zant [1]; Cees Dekker [1]; Leo P. Kouwenhoven [1]; Silvano De Franceschi [1, 2] Progress in [...]

In this paper, a loading technique for improving pulse radiation from bow-tie antennas is introduced. This technique allows transmission of short transient pulses with very small late-time ringing and relatively high radiation efficiency. It makes use of a combination of a constant resistive loading along the antenna and a capacitive loading with linearly increasing reactance toward the antenna ends. The constant resistive loading is applied using volumetric microwave absorbers to cover one side of the antenna and the linear capacitive loading is realized by constructing narrow slots on the antenna surface. Relatively high radiation efficiency is achieved by choosing the location of the slot nearest to the feed point in such a way that radiation from it combines constructively with radiation from the feed point. Using a 0.8-ns monocycle for excitation, the technique results in a level of late-time ringing of lower than--40 dB and at the same time the peak value of the transmitted pulse is 54 % higher than that of the same antenna without loading. Index Terms--Bow-tie antennas, capacitive loading, resistive loading, ultrawide-band antennas.

In this paper, the influence of a lossy ground on the input impedance of dipole and bow-tie antennas excited by a short pulse is investigated. It is shown that the ground influence on the input impedance of transient dipole and bow-tie antennas is significant only for elevations smaller than 1/5 of the wavelength that corresponds to the central frequency of the exciting pulse. Furthermore, a principal difference between the input impedance due to traveling-wave and standing-wave current distributions is pointed out. Index Terms--Bow-tie antenna, dipole antenna, input impedance, transient antenna.

The radiation pattern of the large parabolic reflectors of the Transportable Atmospheric RAdar system (TARA), developed at Delft University of Technology, has been accurately simulated. The electric field integral equation (EFIE) formulation has been applied to a model of the reflectors including the feed housing and supporting struts, discretised using the method of moments. Because the problem is electrically large (the reflector has a diameter of 33 [lambda]) and nonsymmetrical, this lead to a badly conditioned linear system of approximately half a million unknowns. In order to solve this system, an iterative solver (generalized minimum residual method) was used, in combination with the multilevel fast multipole method. Because of the bad conditioning, the system could only be solved by using a huge preconditioner. A new block-incomplete LU preconditioner (ILU) algorithm has been employed to allow for efficient out-of-computer core memory preconditioning. Index Terms--01 reflector antennas, integral equations, method of moments (MoM), multilevel fast multipole method (MLFMA), numerical modeling, preconditioning.

Psychologists and economists have long appreciated the contribution of reward history and expectation to decision-making. Yet we know little about how specific histories of choice and reward lead to an internal representation of the 'value' of possible actions. We approached this problem through an integrated application of behavioral, computational, and physiological techniques. Monkeys were placed in a dynamic foraging environment in which they had to track the changing values of alternative choices through time. In this context, the monkeys' foraging behavior provided a window into their subjective valuation. We found that a simple model based on reward history can duplicate this behavior and that neurons in the parietal cortex represent the relative value of competing actions predicted by this model., Natural environments are characterized by uncertainty in both the sources and timing of rewards (1). Humans and other animals are sensitive to these variables and adapt the statistics of their [...]

Author(s): Pablo Jarillo-Herrero (corresponding author) [1, 2]; Sami Sapmaz [1]; Cees Dekker [1]; Leo P. Kouwenhoven [1, 2]; Herre S. J. van der Zant [1] Optical and electronic phenomena in [...]

The two-dimensional problem of horizontally polarized wave scattering from an air-ground interface is considered. The diffraction problem is formulated by means of the extinction theorem, leading to a system of two simultaneous surface integral equations. The small-slope approximation has been used to solve this system. This solution was used as a fast forward solver in the Monte Carlo simulations of the scattered field near to the rough interface. Properties of the reflected field have been investigated for a single realization of the rough interface as well as for a statistical ensemble of such interfaces. Special attention has been paid to the phase of the reflected field (in the case of a single realization) and to the variance of the reflected field (in the case of a statistical ensemble), which has direct relation with the surface clutter in ground penetrating radars. A principal possibility to retrieve a surface profile from interferometric measurements of the reflected field near the surface is demonstrated. Index Terms--Ground penetrating radar, rough surface scattering, surface clutter.

The procedure for estimating polarization invariants of the backscattering matrix in horizontal-vertical basis is considered for radar observation of arbitrary nonreciprocal objects. Two polarization invariants are added to the well-known six Huynen-Euler invariants. These new invariants (nonreciprocity angle and difference in absolute phases of the symmetric and antisymmetric parts of the scattering matrix) describe the nonreciprocal properties of the object itself. With the simultaneous measurement of all eight quadratures of the scattering matrix elements, the closed-form expressions for calculating the eight polarization invariants are given. The derived expressions are the starting point for complete estimation of the polarization properties of arbitrary radar objects with a nonsymmetric scattering matrix. The given approach can be used to study various polarization effects in remote radar sensing of artificial and natural objects, and also to simulate polarization measurement processes and estimation errors caused by the measurements of scattering matrix elements at different instants. Index Terms--Asymmetric backscattering matrix, horizontal-vertical basis, Huynen-Euler parameters, nonreciprocal object, nonreciprocity parameters, polarization invariants, radar polarimetry, scattering matrix elements quadratures.

In this paper, we present a new technique whereby phase variation signatures are used to profile two-dimensional (2-D) rough surfaces and to discern shallowly buried, small, low-contrast landmines under a flat ground. The method has been tested using data measured over a composite surface containing two rough dielectric surface patches, and over a flat ground under which small, low-contrast antipersonnel (AP) landmines are shallowly buried. The results show that the phase-based technique is capable of profiling rough surfaces and of detecting small, low-contrast landmines with different internal structures buried underneath a flat ground. Index Terms--Ground penetrating radar, phase measurement, phase variation signatures, rough surfaces.

This paper presents a numerical and experimental analysis of a wire bow-tie antenna situated horizontally near a lossy ground. The antenna is basically an array of identical wire dipoles having a common feed point and equal angular separation between two neighboring wires. This antenna is particularly suitable for ultrawide-band applications as it possesses a wideband property and allows a simple realization of resistive loading. It also provides a possibility to easily vary the antenna flare angle for the purpose of antenna matching or to adjust its footprint. In this work a theoretical model of the antenna is developed and verified experimentally. The wires are modeled as a tape-like structure by triangular patches and the antenna is analyzed using a mixed-potential integral equation formulation. Moreover, time-domain solutions are computed using the Fourier transformation, and a time-window technique is employed to calculate the antenna characteristic impedance. Using the model a comprehensive analysis of the antenna performance is carried out. Index Terms--Bow-tie antennas, ground penetrating radar, mixed-potential integral equation, wire antennas.

The electrical noise of mesoscopic devices can be strongly influenced by the quantum motion of electrons. To probe this effect, we have measured the current fluctuations at high frequency (5 to 90 gigahertz) using a superconductor-insulator-superconductor tunnel junction as an on-chip spectrum analyzer. By coupling this frequency-resolved noise detector to a quantum device, we can measure the high-frequency, nonsymmetrized noise as demonstrated for a Josephson junction. The same scheme is used to detect the current fluctuations arising from coherent charge oscillations in a two-level system, a superconducting charge qubit. A narrow band peak is observed in the spectral noise density at the frequency of the coherent charge oscillations., Electrical noise, or fluctuations in the current, has proved to be a powerful tool to probe mesoscopic devices (1). At high frequency, it can bear strong signatures of the dynamics [...]

The adaptive algorithm synthesis theory is used to develop new algorithms applied to radar signals in the detection of turbulent zones in clouds and precipitation. The efficiency of these new algorithms is analyzed. Simulations of weather radar signals on the one hand and modeling and testing of the processing algorithms on the other hand are performed for comparative analysis. The results demonstrate a significant superiority of the new algorithms in comparison with the widely used pulse-pair algorithm.

A new modification of the TEM-horn antenna has been developed for ground-penetrating radar (GPR) applications. The antenna is based on a dielectric wedge, and thus, was named the dielectric wedge antenna. Tapering of the metal flairs has been used to match the antenna to the ground and to reduce the late-time ringing. The finite-difference time-domain model of the antenna has been created to investigate physical processes within the antenna and to optimize its performance. The dielectric wedge antenna has shown a superior (in comparison with the TEM-horn) performance by radiation in different types of the ground and has been used in a novel antenna configuration within a GPR system, which is dedicated for landmine detection. Index Terms--Finite-difference time-domain (FDTD), ground penetrating radar, TEM-horn antenna, transient antenna, ultra-wideband antenna.

Measuring radiation patterns in the time domain provides the antenna characteristics over a wide-frequency spectrum in a single measurement. Such an advantage over traditional measurements in the frequency domain makes the practical implementation of time-domain measurements in compact ranges particularly attractive. In this paper, the time-varying performance of the compact range's quiet zone and plane-wave spectrum are analyzed and supported with simulations. This feasibility study preceded the implementation of a time-domain measurement system in the compact antenna test range of the European Space Research and Technology Center. Measurement results of a linear array are also presented to illustrate the new capabilities of the compact range. Index Terms--Antenna measurements, compact ranges, quiet zone, time domain.

An microwave activities and infrastructures in Europe is presented. The material is organized in 17 sections, each devoted to a country or group of countries and prepared by an internationally renowned microwave expert. In general, each section contains some history of microwaves in the region, and highlights some microwave activities in association with research centers, laboratories and institutions, industry, education, and national conferences. Index Terms--Austria, Balkan, Baltic, Belgium, Czech, Denmark, Europe, Finland, France, Germany, Hungary, Ireland, Israel, Italy, microwave industry, microwave professional societies, microwave research, microwave technology, microwaves, Poland, Portugal, Russia, Slovak, Spain, Sweden, Switzerland, The Netherlands, U.K.

Rare to abundant silicified polyplacophoran faunas occur in the late Wolfcampian Bird Spring Formation and the Leonardian Pequop and Loray Formations in Nevada, the Leonardian Arcturus Formation in Utah, and the early Leonardian Ft. Apache Limestone Member of the Supai Formation in Arizona. The faunas associated with the polyplacophorans are dominated by molluscs. New species include Gryphochiton distinctus, Acutichiton gracilis, A. nevadensis, and Arcochiton richardsoni. Traces of color patterns are present on Arcochiton richardsoni.