Spatial facilitation by a high-performance dragonfly target-detecting neuron

Many animals visualize and track small moving targets at long distances—be they prey, approaching predators or conspecifics. Insects are an excellent model system for investigating the neural mechanisms that have evolved for this challenging task. Specialized small target motion detector (STMD) neurons in the optic lobes of the insect brain respond strongly even when the target size is below the resolution limit of the eye. Many STMDs also respond robustly to small targets against complex stationary or moving backgrounds. We hypothesized that this requires a complex mechanism to avoid breakthrough responses by background features, and yet to adequately amplify the weak signal of tiny targets. We compared responses of dragonfly STMD neurons to small targets that begin moving within the receptive field with responses to targets that approach the same location along longer trajectories. We find that responses along longer trajectories are strongly facilitated by a mechanism that builds up slowly over several hundred milliseconds. This allows the neurons to give sustained responses to continuous target motion, thus providing a possible explanation for their extraordinary sensitivity

Cherenkov and Scintillation Light Separation in Organic Liquid Scintillators

The CHErenkov / Scintillation Separation experiment (CHESS) has been used to demonstrate the separation of Cherenkov and scintillation light in both linear alkylbenzene (LAB) and LAB with 2g/L of PPO as a fluor (LAB/PPO). This is the first such demonstration for the more challenging LAB/PPO cocktail and improves on previous results for LAB. A time resolution of 338 +/- 12 ps FWHM results in an efficiency for identifying Cherenkov photons in LAB/PPO of 70 +/- 3% and 63 +/- 8% for time- and charge-based separation, respectively, with scintillation contamination of 36 +/- 5% and 38 +/- 4%. LAB/PPO data is consistent with a rise time of 0.75 +/- 0.25 ns

Non-deterministic density classification with diffusive probabilistic cellular automata

We present a probabilistic cellular automaton (CA) with two absorbing states which performs classification of binary strings in a non-deterministic sense. In a system evolving under this CA rule, empty sites become occupied with a probability proportional to the number of occupied sites in the neighborhood, while occupied sites become empty with a probability proportional to the number of empty sites in the neighborhood. The probability that all sites become eventually occupied is equal to the density of occupied sites in the initial string.Comment: 4 pages, 4 figure

Juvenile Finfish and Blue Crab Stock Assessment Program Bottom Trawl Survey Annual Data Summary Report Series Volume 1988

The Virginia Institute of Marine Science (VIMS) has conducted a trawl survey of the Virginia tributaries to the Chesapeake Bay dating back to 1955. Over these forty years, methods and objectives have varied according to funding sources and state and/ or federal mandates. The present thrust of the program is to provide juvenile indices of relative abundance of recreationally, commercially, and ecologically important finfish and invertebrates. In 1988, the main area of focus was as a monitoring device of the resources of the Chesapeake Bay and its tributaries, as well as a way to create juvenile indices of key target species. These measures of juvenile abundance are widely used as a key element in the management of the Atlantic States\u27 coastal fishery resources and serve as early indicators of future year class strength. In addition to the river trawl survey, a comprehensive Bay-wide trawl survey of Virginia waters, which was performed in the past with varying sampling methods, was reintroduced in 1988 as a random stratified sampling design. This design was based on depth and three 20° latitudinal regions (top, middle and bottom). The design was altered slightly beginning in 1989 to create four regions (top, upper, lower and bottom). The purpose of this change was to associate each tributary with a mainstem Bay segment. Results are shown as this altered method. The Bay survey accounted for over 70 percent of the annual sampling and two-thirds of the overall 1988 catch. The bay anchovy in 1988 continued to be the most abundant species caught in the river trawl survey and was most abundant overall. The second most abundant species, spot, was captured at near historic high levels in 1988 (the highest since 1984 ). H.ogchoker, weakfish and Atlantic croaker complete the top five species caught overall

Juvenile Finfish and Blue Crab Stock Assessment Program York River Random Stratified Bottom Trawl Survey Data Summary Report Volume R1989-1990

The Virginia Institute of Marine Science (VIMS) has conducted a bottom trawl survey of some fashion since 1955. Historically, sampling has occurred as mid-channel transects at fixed locations spaced at approximately five mile intervals. In the early 1970\u27s, work was performed on the Mobjack Bay and Piankatank River using the standard 30 ft. fishing gear from a large research platform, with a 16 ft. gear towed from an outboard skiff or Chesapeake deadrise at shallow stations (:$; 12 ft.). Linda Pushee Mercer initiated the first random survey of the York River in 1971-72, as part of the results of a pipefish study. This survey, and the realization of an increasing need for a random survey of the main stem Bay and tributaries, were factors in implementing a Bay wide random survey in 1973. This program had a very large spatial coverage in various depth strata, but was very limited in its temporal component. Sampling occurred on a semi-annual basis primarily in January and February, and again in July (Wojcik, 1988a.) Based on previous results from the fixed station sampling, effort was high to provide the desired margin of error (300-700 trawls per survey). This survey was discontinued after several years because of decreased funding. Subsequently, the program returned to a fixed station transect design. These river transects continued monthly until 1988, when the Chesapeake Bay Stock Assessment Committee (CBSAC) funded a monthly random stratified survey of the main stem Bay (Chittenden, 1991) in hopes that this initiative would produce similar surveys of Virginia\u27s major tributaries, the James, York, and Rappahannock Rivers. With this in mind, a pilot survey similar in design was established and implemented for the York River (for logistic reasons), beginning in October 1989. This work was performed independent of, and with a different vessel and smaller fishing gear than the primary sampling of the Bay and tributaries. With the purchase of the solely dedicated trawler RIV Fish Hawk, this random survey of the York was later incorporated and sampled along with the historic fixed stations (June 1991)

Juvenile Finfish and Blue Crab Stock Assessment Program Bottom Trawl Survey Annual Data Summary Report Series Volume 1994

The Virginia Institute of Marine Science (VIMS) has conducted a trawl survey dating back to 1955. Over these forty years methods and objectives have varied according to funding sources and state and/or federal mandates. The present thrust of the program is to provide juvenile indices of relative abundance for recreationally, commercially, and ecologically important finfish and invertebrates. These measures of juvenile abundance are widely used as a key element in the management of the Atlantic States\u27 coastal fishery resources. Estimates of juveniles (age-0) have proven to be a reliable and early indicator of future year-class strength. A review of previously available indices of juvenile abundance for important fishery resource species of the Chesapeake Bay by the Chesapeake Bay Stock Assessment Committee (CBSAC), a federal/ state committee sponsored and funded by the National Oceanic and Atmospheric Administration (NOAA), resulted in the recommendation that, a unified, consistent trawl program should be one of the primary monitoring tools for finfish and crab stock assessment. (Chesapeake Bay Program Stock Assessment Plan, Chesapeake Executive Council 1988). There were several notable survey results for this year. Catch information for 1994 indicated a continuing decline in the blue crab population, although not as pronounced as in recent years. However, the 1994 spawning stock (adult females) was half that of 1993. Juvenile white perch and striped bass catches continued to increase. Summer flounder indices doubled over the disastrous 1992 and 1993 year classes. Atmosperically, winter temperatures were normal with the exception of two extremely cold periods (air temperatures less than 4° C). Summer temperatures were relatively mild compared to 1993 values. The purpose of this summary is to provide an accurate account of trawl survey sampling performed during the calendar year 1994. Previous volumes of this series have served as excellent reference guides to resource managers, scientists, academics, as well as the general public. Since there are other venues which presently detail specific results of these data (Geer et al., 1993), conclusions are kept at a minimum in order to provide the most information in the available space

Outer Retinal Structure in Best Vitelliform Macular Dystrophy

Importance Demonstrating the utility of adaptive optics scanning light ophthalmoscopy (AOSLO) to assess outer retinal structure in Best vitelliform macular dystrophy (BVMD). Objective To characterize outer retinal structure in BVMD using spectral-domain optical coherence tomography (SD-OCT) and AOSLO. Design, Setting, and Participants Prospective, observational case series. Four symptomatic members of a family with BVMD with known BEST1 mutation were recruited at the Advanced Ocular Imaging Program research lab at the Medical College of Wisconsin Eye Institute, Milwaukee. Intervention Thickness of 2 outer retinal layers corresponding to photoreceptor inner and outer segments was measured using SD-OCT. Photoreceptor mosaic AOSLO images within and around visible lesions were obtained, and cone density was assessed in 2 subjects. Main Outcome and Measure Photoreceptor structure. Results Each subject was at a different stage of BVMD, with photoreceptor disruption evident by AOSLO at all stages. When comparing SD-OCT and AOSLO images from the same location, AOSLO images allowed for direct assessment of photoreceptor structure. A variable degree of retained photoreceptors was seen within all lesions. The photoreceptor mosaic immediately adjacent to visible lesions appeared contiguous and was of normal density. Fine hyperreflective structures were visualized by AOSLO, and their anatomical orientation and size were consistent with Henle fibers. Conclusions and Relevance The AOSLO findings indicate that substantial photoreceptor structure persists within active lesions, accounting for good visual acuity in these patients. Despite previous reports of diffuse photoreceptor outer segment abnormalities in BVMD, our data reveal normal photoreceptor structure in areas adjacent to clinical lesions. This study demonstrates the utility of AOSLO for understanding the spectrum of cellular changes that occur in inherited degenerations such as BVMD. Photoreceptors are often significantly affected at various stages of inherited degenerations, and these changes may not be readily apparent with current clinical imaging instrumentation

Parity Problem With A Cellular Automaton Solution

The parity of a bit string of length $N$ is a global quantity that can be efficiently compute using a global counter in ${O} (N)$ time. But is it possible to find the parity using cellular automata with a set of local rule tables without using any global counter? Here, we report a way to solve this problem using a number of $r=1$ binary, uniform, parallel and deterministic cellular automata applied in succession for a total of ${O} (N^2)$ time.Comment: Revtex, 4 pages, final version accepted by Phys.Rev.

Footprints of Statistical Anisotropies

We propose and develop a formalism to describe and constrain statistically anisotropic primordial perturbations. Starting from a decomposition of the primordial power spectrum in spherical harmonics, we find how the temperature fluctuations observed in the CMB sky are directly related to the coefficients in this harmonic expansion. Although the angular power spectrum does not discriminate between statistically isotropic and anisotropic perturbations, it is possible to define analogous quadratic estimators that are direct measures of statistical anisotropy. As a simple illustration of our formalism we test for the existence of a preferred direction in the primordial perturbations using full-sky CMB maps. We do not find significant evidence supporting the existence of a dipole component in the primordial spectrum.Comment: 26 pages, 5 double figures. Uses RevTeX

Prospek Jawawut (Pennisetum Spp. ) sebagai Tanaman Pangan Serealia Alternatif

Untuk meningkatkan ketahanan pangan dan diversifikasi pangan, Indonesia dapatmemanfaatkan lahan kering yang cukup luas jumlahnya. Jawawut (Pennisetumspp.) memiliki potensi yang sangat baik sebagai tanaman pangan alternatifditinjau dari aspek kandungan gizi, dan kemampuan tumbuhnya di daerahberiklim kering. Dilihat dari segi kandungan gizinya, jawawut berpotensi sebagaisumber energi, protein, kalsium, vitamin B1, riboflavin (vitamin B2), sedangkannutrisi lainnya setara dengan beras. Potensi hasil yang dapat dicapai di Indonesiaadalah 4 ton per ha pada kondisi agroekologi yang marginal, dimanapertumbuhan serealia lainnya kurang berhasil. Jawawut dipanen sebagai tanamanpangan semusim