Convolutional code performance in planetary entry channels

The planetary entry channel is modeled for communication purposes representing turbulent atmospheric scattering effects. The performance of short and long constraint length convolutional codes is investigated in conjunction with coherent BPSK modulation and Viterbi maximum likelihood decoding. Algorithms for sequential decoding are studied in terms of computation and/or storage requirements as a function of the fading channel parameters. The performance of the coded coherent BPSK system is compared with the coded incoherent MFSK system. Results indicate that: some degree of interleaving is required to combat time correlated fading of channel; only modest amounts of interleaving are required to approach performance of memoryless channel; additional propagational results are required on the phase perturbation process; and the incoherent MFSK system is superior when phase tracking errors are considered

Performance of convolutional codes on fading channels typical of planetary entry missions

The performance of convolutional codes in fading channels typical of the planetary entry channel is examined in detail. The signal fading is due primarily to turbulent atmospheric scattering of the RF signal transmitted from an entry probe through a planetary atmosphere. Short constraint length convolutional codes are considered in conjunction with binary phase-shift keyed modulation and Viterbi maximum likelihood decoding, and for longer constraint length codes sequential decoding utilizing both the Fano and Zigangirov-Jelinek (ZJ) algorithms are considered. Careful consideration is given to the modeling of the channel in terms of a few meaningful parameters which can be correlated closely with theoretical propagation studies. For short constraint length codes the bit error probability performance was investigated as a function of E sub b/N sub o parameterized by the fading channel parameters. For longer constraint length codes the effect was examined of the fading channel parameters on the computational requirements of both the Fano and ZJ algorithms. The effects of simple block interleaving in combatting the memory of the channel is explored, using the analytic approach or digital computer simulation

Removal of luminal content protects the small intestine during hemorrhagic shock but is not sufficient to prevent lung injury.

The small intestine plays a key role in the pathogenesis of multiple organ failure following circulatory shock. Current results show that reduced perfusion of the small intestine compromises the mucosal epithelial barrier, and the intestinal contents (including pancreatic digestive enzymes and partially digested food) can enter the intestinal wall and transport through the circulation or mesenteric lymph to other organs such as the lung. The extent to which the luminal contents of the small intestine mediate tissue damage in the intestine and lung is poorly understood in shock. Therefore, rats were assigned to three groups: No-hemorrhagic shock (HS) control and HS with or without a flushed intestine. HS was induced by reducing the mean arterial pressure (30 mmHg; 90 min) followed by return of shed blood and observation (3 h). The small intestine and lung were analyzed for hemorrhage, neutrophil accumulation, and cellular membrane protein degradation. After HS, animals with luminal contents had increased neutrophil accumulation, bleeding, and destruction of E-cadherin in the intestine. Serine protease activity was elevated in mesenteric lymph fluid collected from a separate group of animals subjected to intestinal ischemia/reperfusion. Serine protease activity was elevated in the plasma after HS but was detected in lungs only in animals with nonflushed lumens. Despite removal of the luminal contents, lung injury occurred in both groups as determined by elevated neutrophil accumulation, permeability, and lung protein destruction. In conclusion, luminal contents significantly increase intestinal damage during experimental HS, suggesting transport of luminal contents across the intestinal wall should be minimized

Search algorithm for a gravitational wave signal in association with Gamma Ray Burst GRB030329 using the LIGO detectors

One of the brightest Gamma Ray Burst ever recorded, GRB030329, occurred during the second science run of the LIGO detectors. At that time, both interferometers at the Hanford, WA LIGO site were in lock and acquiring data. The data collected from the two Hanford detectors was analyzed for the presence of a gravitational wave signal associated with this GRB. This paper presents a detailed description of the search algorithm implemented in the current analysis.Comment: To appear in the Proceedings of 8th Gravitational Wave Data Analysis Workshop (Milwaukee, WI) (Class. Quantum Grav.

All-sky search of NAUTILUS data

A search for periodic gravitational-wave signals from isolated neutron stars in the NAUTILUS detector data is presented. We have analyzed half a year of data over the frequency band $$Hz, the spindown range$$ Hz/s and over the entire sky. We have divided the data into 2 day stretches and we have analyzed each stretch coherently using matched filtering. We have imposed a low threshold for the optimal detection statistic to obtain a set of candidates that are further examined for coincidences among various data stretches. For some candidates we have also investigated the change of the signal-to-noise ratio when we increase the observation time from two to four days. Our analysis has not revealed any gravitational-wave signals. Therefore we have imposed upper limits on the dimensionless gravitational-wave amplitude over the parameter space that we have searched. Depending on frequency, our upper limit ranges from $3.4 \times 10^{-23}$ to $1.3 \times 10^{-22}$. We have attempted a statistical verification of the hypotheses leading to our conclusions. We estimate that our upper limit is accurate to within 18%.Comment: LaTeX, 12 page

IGEC2: A 17-month search for gravitational wave bursts in 2005-2007

We present here the results of a 515 days long run of the IGEC2 observatory, consisting of the four resonant mass detectors ALLEGRO, AURIGA, EXPLORER and NAUTILUS. The reported results are related to the fourfold observation time from Nov. 6 2005 until Apr. 14 2007, when Allegro ceased its operation. This period overlapped with the first long term observations performed by the LIGO interferometric detectors. The IGEC observations aim at the identification of gravitational wave candidates with high confidence, keeping the false alarm rate at the level of 1 per century, and high duty cycle, namely 57% with all four sites and 94% with at least three sites in simultaneous observation. The network data analysis is based on time coincidence searches over at least three detectors: the four 3-fold searches and the 4-fold one are combined in a logical OR. We exchanged data with the usual blind procedure, by applying a unique confidential time offset to the events in each set of data. The accidental background was investigated by performing sets of 10^8 coincidence analyses per each detector configuration on off-source data, obtained by shifting the time series of each detector. The thresholds of the five searches were tuned so as to control the overall false alarm rate to 1/century. When the confidential time shifts was disclosed, no gravitational wave candidate was found in the on-source data. As an additional output of this search, we make available to other observatories the list of triple coincidence found below search thresholds, corresponding to a false alarm rate of 1/month.Comment: 10 pages, 8 figures Accepted for publication on Phys. Rev.

Correlation between Gamma-Ray bursts and Gravitational Waves

The cosmological origin of $\gamma$-ray bursts (GRBs) is now commonly accepted and, according to several models for the central engine, GRB sources should also emit at the same time gravitational waves bursts (GWBs). We have performed two correlation searches between the data of the resonant gravitational wave detector AURIGA and GRB arrival times collected in the BATSE 4B catalog. No correlation was found and an upper limit \bbox{$h_{\text{RMS}} \leq 1.5 \times 10^{-18}$} on the averaged amplitude of gravitational waves associated with $\gamma$-ray bursts has been set for the first time.Comment: 7 pages, 3 figures, submitted to Phys. Rev.

Initial operation of the International Gravitational Event Collaboration

The International Gravitational Event Collaboration, IGEC, is a coordinated effort by research groups operating gravitational wave detectors working towards the detection of millisecond bursts of gravitational waves. Here we report on the current IGEC resonant bar observatory, its data analysis procedures, the main properties of the first exchanged data set. Even though the available data set is not complete, in the years 1997 and 1998 up to four detectors were operating simultaneously. Preliminary results are mentioned.Comment: 8 pages, 2 figures, 3 tables; Proceeding of the GWDAW'99. Submitted to the International Journal of Modern Physic

A systematic, intensive statistical investigation of data from the Comprehensive Analysis of Reported Drugs (CARD) for compliance and illicit opioid abstinence in substance addiction treatment with buprenorphine/naloxone

BACKGROUND: Buprenorphine and naloxone (bup/nal), a combination partial mu receptor agonist and low-dose delta mu antagonist, is presently recommended and used to treat opioid-use disorder. However, a literature review revealed a paucity of research involving data from urine drug tests that looked at compliance and abstinence in one sample. METHOD: Statistical analysis of data from the Comprehensive Analysis of Reported Drugs (CARD) was used to assess compliance and abstinence during treatment in a large cohort of bup/nal patients attending chemical-dependency programs from eastern USA in 2010 and 2011. RESULTS: Part 1: Bup/nal was present in 93.4% of first (n = 1,282; p \u3c.0001) and 92.4% of last (n = 1,268; p \u3c.0001) urine samples. Concomitantly, unreported illicit drugs were present in 47.7% (n = 655, p =.0261) of samples. Patients who were compliant to the bup/nal prescription were more likely than noncompliant patients to be abstinent during treatment (p =.0012; odds ratio = 1.69 with 95% confidence interval (1.210, 2.354). Part 2: An analysis of all samples collected in 2011 revealed a significant improvement in both compliance (p \u3c 2.2 × 1