Lake Tahoe bottom characteristics extracted from SHOALS lidar waveform data and compared to backscatter data from a Multibeam echo sounder

The waveforms recorded by airborne lidar bathymetry (ALB) systems are currently processed only for depth information. In addition to bathymetry, multibeam echo sounder (MBES) systems provide backscatter data in which regions of different acoustic properties are distinguishable. These regions can often be correlated to different bottom types. Initial attempts to extract equivalent data from the ALB waveforms have confirmed the expectation that such information is encoded in those waveforms. Water clarity, bathymetry, and bottom type control the detailed shapes of ALB waveforms in different ways. Specific features of a bottom-reflected signal can be identified, for example its rise-time and amplitude, and used for clustering and classifying the individual data points. Two data sets from Lake Tahoe are available for comparison: ALB data from the SHOALS (scanning hydrographic operational airborne lidar survey) system of the US Army Corps of Engineers, and Simrad EM1000 MBES data from the USGS. Feature extraction, clustering, and classification of the SHOALS data reveals changes in the optical bottom reflectance characteristics that are echoed in the acoustic bottom backscatter properties

Pyramidal cells of the frontal lobe: All the more spinous to think with

The basal dendritic arbors of pyramidal cells in prefrontal areas 10, 11, and 12 of the macaque monkey were revealed by intracellular injection in fixed, flat-mounted, cortical slices. The size, number of branches, and spine density of the basal dendrites were quantified and compared with those of pyramidal cells in the occipital, parietal, and temporal lobes. These analyses revealed that cells in the frontal lobe were significantly more spinous than those in the other lobes, having as many as 16 times more spines than cells in the primary visual area (V1), four times more those in area 7a, and 45% more than those in area TE. As each dendritic spine receives at least one excitatory input, the large number of spines reported for layer III cells in prefrontal cortex suggests that they are capable of integrating a greater number of excitatory inputs than layer III pyramidal cells so far studied in the occipital, parietal, and temporal lobes. The ability to integrate a large number of excitatory inputs may be important for the sustained tonic activity characteristic of neurons in prefrontal cortex and their role in memory and cognition

Gene regulatory networks: a coarse-grained, equation-free approach to multiscale computation

We present computer-assisted methods for analyzing stochastic models of gene regulatory networks. The main idea that underlies this equation-free analysis is the design and execution of appropriately-initialized short bursts of stochastic simulations; the results of these are processed to estimate coarse-grained quantities of interest, such as mesoscopic transport coefficients. In particular, using a simple model of a genetic toggle switch, we illustrate the computation of an effective free energy and of a state-dependent effective diffusion coefficient that characterize an unavailable effective Fokker-Planck equation. Additionally we illustrate the linking of equation-free techniques with continuation methods for performing a form of stochastic "bifurcation analysis"; estimation of mean switching times in the case of a bistable switch is also implemented in this equation-free context. The accuracy of our methods is tested by direct comparison with long-time stochastic simulations. This type of equation-free analysis appears to be a promising approach to computing features of the long-time, coarse-grained behavior of certain classes of complex stochastic models of gene regulatory networks, circumventing the need for long Monte Carlo simulations.Comment: 33 pages, submitted to The Journal of Chemical Physic

Pyramidal Cells, Patches, and Cortical Columns: a Comparative Study of Infragranular Neurons in TEO, TE, and the Superior Temporal Polysensory Area of the Macaque Monkey

The basal dendritic arbors of layer III pyramidal neurons are known to vary systematically among primate visual areas. Generally, those in areas associated with "higher" level cortical processing have larger and more spinous dendritic arbors, which may be an important factor for determining function within these areas. Moreover, the tangential area of their arbors are proportional to those of the periodic supragranular patches of intrinsic connections in many different areas. The morphological parameters of both dendritic and axon arbors may be important for the sampling strategies of cells in different cortical areas. However, in visual cortex, intrinsic patches are a feature of supragranular cortex, and are weaker or nonexistent in infragranular cortex. Thus, the systematic variation in the dendritic arbors of pyramidal cells in supragranular cortex may reflect intrinsic axon projections, rather than differences in columnar organization. The present study was aimed at establishing whether cells in the infragranular layers also vary in terms of dendritic morphology among different cortical areas, and whether these variations mirror the ones demonstrated in supragranular cortex. Layer V pyramidal neurons were injected with Lucifer yellow in flat-mounted cortical slices taken from cytoarchitectonic areas TEO and TE and the superior polysensory area (STP) of the macaque monkey. The results demonstrate that cells in STP were larger, had more bifurcations, and were more spinous than those in TE, which in turn were larger, had more bifurcations and were more spinous than those in TEO. These results parallel morphological variation seen in layer III pyramidal neurons, suggesting that increasing complexity of basal dendritic arbors of cells, with progression through higher areas of the temporal lobe, is a general organizational principle. It is proposed that the differences in microcircuitry may contribute to the determination of the functional signatures of neurons in different cortical areas. Furthermore, these results provide evidence that intrinsic circuitry differs across cortical areas, which may be important for theories of columnar processing

Zenithal bistability in a nematic liquid crystal device with a monostable surface condition

The ground-state director configurations in a grating-aligned, zenithally bistable nematic device are calculated in two dimensions using a Q tensor approach. The director profiles generated are well described by a one-dimensional variation of the director across the width of the device, with the distorted region near the grating replaced by an effective surface anchoring energy. This work shows that device bistability can in fact be achieved by using a monostable surface term in the one-dimensional model. This implies that is should be possible to construct a device showing zenithal bistability without the need for a micropatterned surface

Regression-adjusted small area estimates of functional dependency in the noninstitutionalized American population age 65 and over.

Health planning efforts for the population age 65 and over have been hampered continually by the lack of reliable estimates of the noninstitutionalized long-term care population. Until recently national estimates were virtually nonexistent, and reliable small area estimates remain unavailable. However, with the recent publication of several national surveys and the 1990 Census, synthetic estimates can be made for states and counties by using multivariate methods to model functional dependency at the national level, and then applying the predicted probabilities to corresponding state and county data. Using the 1984 National Health Interview Survey's Supplement on Aging and the 1986 Area Health Resources File System, we have produced log-linear regression models that include demographic and contextual variables as predictors of functional dependency among the noninstitutionalized population age 65 and over. Age, sex, race, and the percent of the 65 and over population who reside in poverty were found to be significant predictors of functional dependency. Applying these models to 1986 Medicare Enrollment Statistics, regression-adjusted synthetic estimates of two levels of functional dependency were produced for all states and - as examples of how the rates can be used to produce additional synthetic estimates - the largest county in each state. We also produced point estimates and standard errors for the national prevalence of functional dependency among the noninstitutionalized population age 65 and over

Probing the Super Star Cluster Environment of NGC 1569 Using FISICA

We present near-IR JH spectra of the central regions of the dwarf starburst galaxy NGC 1569 using the Florida Image Slicer for Infrared Cosmology and Astrophysics (FISICA). The dust-penetrating properties and available spectral features of the near-IR, combined with the integral field unit (IFU) capability to take spectra of a field, make FISICA an ideal tool for this work. We use the prominent [He I] (1.083\mu m) and Pa\beta (1.282 \mu m) lines to probe the dense star forming regions as well as characterize the general star forming environment around the super star clusters (SSCs) in NGC 1569. We find [He I] coincident with CO clouds to the north and west of the SSCs, which provides the first, conclusive evidence for embedded star clusters here.Comment: 6 pages, 3 figures, accepted for publication in the MNRA

A FLAMINGOS Deep Near Infrared Imaging Survey of the Rosette Complex I: Identification and Distribution of the Embedded Population

We present the results of a deep near-infrared imaging survey of the Rosette Complex. We studied the distribution of young embedded sources using a variation of the Nearest Neighbor Method applied to a carefully selected sample of near-infrared excess (NIRX) stars which trace the latest episode of star formation in the complex. Our analysis confirmed the existence of seven clusters previously detected in the molecular cloud, and identified four more clusters across the complex. We determined that 60% of the young stars in the complex and 86% of the stars within the molecular cloud are contained in clusters, implying that the majority of stars in the Rosette formed in embedded clusters. We compare the sizes, infrared excess fractions and average extinction towards individual clusters to investigate their early evolution and expansion. We found that the average infrared excess fraction of clusters increases as a function of distance from NGC 2244, implying a temporal sequence of star formation across the complex. This sequence appears to be primordial, possibly resulting from the formation and evolution of the molecular cloud and not from the interaction with the HII region.Comment: Accepted by Astrophysical Journa