Simultaneous Multicolor Detection of Faint Galaxies in the Hubble Deep Field

We present a novel way to detect objects when multiband images are available. Typically, object detection is performed in one of the available bands or on a somewhat arbitrarily co-added image. Our technique provides an almost optimal way to use all the color information available. We build up a composite image of the N passbands where each pixel value corresponds to the probability that the given pixel is just sky. By knowing the probability distribution of sky pixels (a chi-square distribution with N degrees of freedom), the data can be used to derive the distribution of pixels dominated by object flux. From the two distributions an optimal segmentation threshold can be determined. Clipping the probability image at this threshold yields a mask, where pixels unlikely to be sky are tagged. After using a standard connected-pixel criterion, the regions of this mask define the detected objects. Applying this technique to the Hubble Deep Field data, we find that we can extend the detection limit of the data below that possible using linearly co-added images. We also discuss possible ways of enhancing object detection probabilities for certain well defined classes of objects by using various optimized linear combinations of the pixel fluxes (optimal subspace filtering).Comment: 8 pages, 5 figures (4 postscript, 1 JPEG). To be published in A

The Dark Matter Contribution to Galactic Diffuse Gamma Ray Emission

Observations of diffuse Galactic gamma ray emission (DGE) by the Fermi Large Area Telescope (LAT) allow a detailed study of cosmic rays and the interstellar medium. However, diffuse emission models of the inner Galaxy underpredict the Fermi-LAT data at energies above a few GeV and hint at possible non-astrophysical sources including dark matter (DM) annihilations or decays. We present a study of the possible emission components from DM using the high-resolution Via Lactea II N-body simulation of a Milky Way-sized DM halo. We generate full-sky maps of DM annihilation and decay signals that include modeling of the adiabatic contraction of the host density profile, Sommerfeld enhanced DM annihilations, $p$-wave annihilations, and decaying DM. We compare our results with the DGE models produced by the Fermi-LAT team over different sky regions, including the Galactic center, high Galactic latitudes, and the Galactic anti-center. This work provides possible templates to fit the observational data that includes the contribution of the subhalo population to DM gamma-ray emission, with the significance depending on the annihilation/decay channels and the Galactic regions being considered.Comment: Published by PR

All degree six local unitary invariants of k qudits

We give explicit index-free formulae for all the degree six (and also degree four and two) algebraically independent local unitary invariant polynomials for finite dimensional k-partite pure and mixed quantum states. We carry out this by the use of graph-technical methods, which provides illustrations for this abstract topic.Comment: 18 pages, 6 figures, extended version. Comments are welcom

Apparent Clustering of Intermediate-redshift Galaxies as a Probe of Dark Energy

We show the apparent redshift-space clustering of galaxies in redshift range of 0.2--0.4 provides surprisingly useful constraints on dark energy component in the universe, because of the right balance between the density of objects and the survey depth. We apply Fisher matrix analysis to the the Luminous Red Galaxies (LRGs) in the Sloan Digital Sky Survey (SDSS), as a concrete example. Possible degeneracies in the evolution of the equation of state (EOS) and the other cosmological parameters are clarified.Comment: 5 pages, 3 figures, Phys.Rev.Lett., replaced with the accepted versio

High efficacy of photodynamic therapy on rat endometrium after systemic administration of benzoporphyrin derivative monoacid ring A

BACKGROUND: The aim of this study was to evaluate the effect of the benzoporphyrin derivative monoacid ring A (verteporfin)‐mediated photodynamic therapy (PDT) on rat endometrium and to determine the optimal drug concentration for endometrial ablation. METHODS: Five minutes after i.v. injection of different concentrations of verteporfin into 24 female Sprague-Dawley rats, 630nm light treatment was delivered for 500 s (120J/cm2) to the left horn of the uterus. The 24 rats were divided into six groups according to the drug dose injected, four rats per group: group I (2 mg/kg), group II (1 mg/kg), and groups III, IV, V and VI with 0.5, 0.25, 0.125 and 0.0625mg/kg respectively. Four days later, the rat uteri were analysed by light microscopy. RESULTS: Endometrial destruction was seen in all six groups, with the most significant result in group I (P < 0.008). Conservation of the myometrium was most significant in groups III, IV, V and VI. Acute inflammatory cells in the stromal endometrium were recorded mainly in groups I and II. However, the drug dosage that was most significant in destroying the glands with conservation of the myometrium and not causing severe inflammation was between 0.5 and 0.125mg/kg. CONCLUSIONS: Verteporfin was effective in endometrial ablation in all our animal groups, and the dose range of 0.5-0.125mg/kg appeared to be adequate. This observation will have to be scaled for clinical applicatio

Large Scale Clustering of Sloan Digital Sky Survey Quasars: Impact of the Baryon Density and the Cosmological Constant

We report the first result of the clustering analysis of Sloan Digital Sky Survey (SDSS) quasars. We compute the two-point correlation function (2PCF) of SDSS quasars in redshift space at $8h^{-1}{\rm Mpc} < s < 500h^{-1}{\rm Mpc}$, with particular attention to its baryonic signature. Our sample consists of 19986 quasars extracted from the SDSS Data Release 4 (DR4). The redshift range of the sample is $0.72 \le z \le 2.24$ (the mean redshift is $\bar z = 1.46$) and the reddening-corrected $i$-band apparent magnitude range is $15.0 \le m_{i,{\rm rc}} \le 19.1$. Due to the relatively low number density of the quasar sample, the bump in the power spectrum due to the baryon density, $\Omega_{\rm b}$, is not clearly visible. The effect of the baryon density is, however, to distort the overall shape of the 2PCF.The degree of distortion makes it an interesting alternate measure of the baryonic signature. Assuming a scale-independent linear bias and the spatially flat universe, i.e., $\Omega_{\rm b} + \Omega_{\rm d} + \Omega_\Lambda =1$, where $\Omega_{\rm d}$ and $\Omega_\Lambda$ denote the density parameters of dark matter and the cosmological constant, we combine the observed quasar 2PCF and the predicted matter 2PCF to put constraints on $\Omega_{\rm b}$ and $\Omega_\Lambda$. Our result is fitted as $0.80- 2.8\Omega_{\rm b} < \Omega_\Lambda < 0.90 - 1.4\Omega_{\rm b}$ at the 2$\sigma$ confidence level, which is consistent with results from other cosmological observations such as WMAP. (abridged)Comment: 26 pages, 12 figures, Accepted for publication in the PAS

Post-movement beta synchronization in Wilson's disease [Abstract]

Objective: To analyze the post-movement beta synchronization(PMBS) of the electroencephalogram (EEG) in Wilson’s disease. Background: Wilson’s disease is an autosomal recessive inherited disorder of copper metabolism. Its most common neurological symptoms (tremor, parkinsonism, dystonia, ataxia, chorea, dysarthria) are mainly related to dysfunction of the basal ganglia-thalamo-corticaland the cerebello-thalamo-cortical pathways. Post-movement beta synchronization is a transient power increase in the beta frequency band, which can be detected above the sensorimotor cortex 1-2 s after the termination of the movement. It is postulated that it reflects active inhibition and information processing. In essential tremor normal PMBS power but increased latency can be measured whereas in Parkinson’s disease PMBS latency is normal but its power is decreased. Methods: Ten patients with neurological manifestation of Wilson’s disease and ten controls performed self-paced movement with the dominant hand during EEG acquisition. Five electrodes located in the region of the sensorimotor cortical areas were selected for evaluation (C3, C1, Cz, C2, C4). The power and latency of post-movement beta synchronization were calculated after power spectral analysis with multi taper method. Results: PMBS power contralateral to the movement was significantly lower in patients with Wilson’s disease (1,9460,7%) than in controls (2,560,7%; p50,01). In all electrode position the latency of PMBS was significantly longer in the Wilson group (1,3460,45s) compared to controls (0,9360,44s; p50,005). The severity and type of neurological symptoms and the location and size of the MRI abnormalities were not correlated with the changes of PMBS. However, alterations of PMBS tended to be more pronounced in patients with more severe neurological symptoms. Conclusions: PMBS is affected in Wilson’s disease with neurological manifestation indicating altered information processing in the sensorimotor cortex. PMBS abnormalities are the combination of changes observed in Parkinson’s disease (decrease of power) and essential tremor (elongation of latencies). This may reflect the pathological changes in both the basal ganglia-thalamo-cortical circuit and cerebello-thalamo-cortical loop in Wilson’s disease