Detectability of Gravitational Waves from SN 1987A

We discuss the potential for detection of gravitational waves from a rapidly spinning neutron star produced by supernova 1987A taking the parameters claimed by Middleditch et al. (2000) at face value. Asssuming that the dominant mechanism for spin down is gravitational waves emitted by a freely precessing neutron star, it is possible to constrain the wobble angle, the effective moment of inertai of the precessing crust and the crust cracking stress limit. Our analysis, suggests that, if the interpretation of the Middleditch data is correct, the compact remnant of SN 1987A may well provide a reliable and predictable source of gravitational waves well within the capability of LIGO II

Gravitational radiation detectability of supernova 1987A\u27s remnant fully matched filter for double resonant gravitational detector

Part I There is some observational evidence of the presence of a pulsating light source in the remnant of the supernova (SN) 1987A [1]. This source is considered to be a rotating neutron star. Fourier analysis of the light intensity of this source reveals a main narrow frequency peak and side bands that are understood as a modulation of the main sinusoidal signal. A particular model of the neutron star invokes a precessing object to explain the modulation. From the Fourier spectrum of the source and changes in the frequency value, we can determine important parameters of the spinning neutron star as rotation frequency, precession frequency and spin-down rate. The neutron star is believed to spin down due to the emission of gravitational waves. We give a precise calculation of the strain value of the gravitational waves reaching earth and discuss the possibility of detection of this radiation by existing and soon on line gravitational waves detectors. Our conclusion is that just a few days of integration time will be sufficient to detect the signal using the next generation detectors as LIGO II. Part II Historically, in the search for burst signals, the ALLEGRO Gravitational Group used a matched filter constructed in the time domain, and with the particular characteristic of separating the information from the two resonant modes of the bar. The information from the two resonant modes is treated separately until the end when the total energy of the response of the bar is estimated, summing each mode output (we call this filter partially matched). We developed a filter (called fully matched) that doesn\u27t separate the two resonant modes and treats the two modes system as a whole. This filter is constructed in the Fourier domain. We compared the performance of partially matched filter with the fully matched filter applying both filters to simulated and real data. The main conclusion is that even in the one mode case, but particularly in the two modes case, the fast filter is more efficient than the slow filter. In addition, we attempt also to explain why the fully matched is a better filter than the partially matched filter

I cetacei del Golfo di Corinto, Grecia

Il Golfo di Corinto, nella Grecia centrale, è un bacino semichiuso di 2400 km2. Con le sue ampie piattaforme continentali, ripi-de zone di scarpata e acque profonde fino a 900 m, il Golfo è letteralmente un piccolo “mediterraneo”, non solo perché circondato da terre e rilievi montuosi, ma anche per la varietà degli ecosistemi marini che ospita. Tre specie di cetacei sono presenti in queste acque: 1) la stenella striata (Stenella coerule-oalba), un delfino tipico di ambienti pelagici; 2) il delfino comune (Delphinus delphis), che in Mediterraneo è osservabile sia in ambien-te pelagico sia in zone di scarpata e presso la costa; 3) il tursiope (Tursiops truncatus), tipico della piattaforma continentale. In ag-giunta, il Golfo ospita un quarto odontoce-to: un solo esemplare di grampo (Grampus griseus)...

Enhanced Memory Consolidation Via Automatic Sound Stimulation During Non-REM Sleep

Introduction: Slow-wave sleep (SWS) slow waves and sleep spindle activity have been shown to be crucial for memory consolidation. Recently, memory consolidation has been causally facilitated in human participants via auditory stimuli phase-locked to SWS slow waves. Aims: Here, we aimed to develop a new acoustic stimulus protocol to facilitate learning and to validate it using different memory tasks. Most importantly, the stimulation setup was automated to be applicable for ambulatory home use. Methods: Fifteen healthy participants slept 3 nights in the laboratory. Learning was tested with 4 memory tasks (word pairs, serial finger tapping, picture recognition, and face-name association). Additional questionnaires addressed subjective sleep quality and overnight changes in mood. During the stimulus night, auditory stimuli were adjusted and targeted by an unsupervised algorithm to be phase-locked to the negative peak of slow waves in SWS. During the control night no sounds were presented. Results: Results showed that the sound stimulation increased both slow wave (p =.002) and sleep spindle activity (p Conclusions: We showed that the memory effect of the SWS-targeted individually triggered single-sound stimulation is specific to verbal associative memory. Moreover, the ambulatory and automated sound stimulus setup was promising and allows for a broad range of potential follow-up studies in the future.Peer reviewe

Optimizing abundance estimates of striped dolphins in the Gulf of Corinth, Greece

Monitoring cetacean abundance is often challenged by insufficient funding and/or effort. Large sample sizes are required to obtain reliable estimates via Capture Mark Recapture (CMR) models. Dataset simulations and power analysis can be used to assess 1) minimum sample size to achieve reliable estimates within one sampling season, and 2) the number of repeated estimates required to detect abundance trends. We used photo-identification data from June-September 2012 to estimate abundance of striped dolphins Stenella coeruleoalba in the Gulf of Corinth, Greece, using CMR models. To evaluate minimum sample size needed within one sampling season, we used dataset simulations in program MARK and compared accuracy and precision obtained with increasing sample sizes. We then used Gerrodette’s inequality model to perform a power analysis and compare the smallest annual percent declines detectable by decennial monitoring plans based on 1) one estimate per year, 2) one estimate every two years, and 3) one estimate every five years. The effect of different levels of precision of the estimates (CV=0.01-0.04) was also investigated. Population abundance was estimated at 1,309 (SE=62.45; CV=0.05; 95% CI=1,192–1,437) for open models and at 1,293 (SE=53.66; CV=0.04; 95% CI=1,192–1,403) for closed models. These estimates are substantially larger that those obtained in a previous CMR study on 2009 data, and need to be validated. To obtain reasonably accurate estimates within one sampling season, simulations indicated a minimum sample size of 8 capture occasions, with minimum capture probabilities of 0.5 for closed models and 0.7 for open models. Furthermore, a power analysis indicated that the smallest annual declines (5%–12.5%) could be detected by monitoring plans providing one estimate every two years. High levels of precision are required (CV=0.01 to detect a 5% annual decline). This information is being used to set monitoring goals and optimize the available resources

Striped dolphin abundance in the Gulf of Corinth, Greece: dataset simulations help improve sampling design

Estimating wildlife population abundance is essential to evaluate the extinction risk of local populations and support conservation management. Photographic Capture mark-recapture (CMR) is a widely-used technique to assess cetacean abundance. However, reliability of estimates is strongly dependent on sample size. CMR software such as MARK can be used to simulate datasets sampled from virtual populations of known size. Population size can be estimated with CMR models from such datasets and, being the real abundance (Ntrue) known, is then possible to assess the models’ performance under different sample size scenarios. We used photo-identification data from June-September 2012 to estimate population size (N) as well as capture and survival probability (p and phi, respectively) of striped dolphins Stenella coeruleoalba in the semi-enclosed Gulf of Corinth. We then used these estimates to simulate datasets obtained with different levels of sampling effort. Finally, we estimated N from the simulated datasets and 1) compared the accuracy and precision of estimates obtained with closed and open population CMR models with samples of different size and 2) identified an 'optimal' sampling strategy. Reliable estimates (100% included in a ± 50 interval around Ntrue) with both models were obtained with 7+ capture occasions and a minimum capture probability of 0.5 for closed and 0.7 for open models. These results provide a way forward for improved sampling design

Bottlenose dolphin abundance in the Northern Evoikos Gulf, Greece

The Mediterranean subpopulation of the common bottlenose dolphin Tursiops truncatus has been classified as Vulnerable in the IUCN Red List. However, population size data are only available for a few Mediterranean subareas, hampering understanding of bottlenose dolphin status and trends. To contribute baseline information, we assessed bottlenose dolphin abundance in the Northern Evoikos Gulf, a 960 km2 semi-enclosed basin in central Greece exposed to high heavy-industry and fishing impacts. Boat-based surveys covering the entire Gulf were conducted in October 2010 and March-April 2011, totalling 3340 km of navigation over 39 survey days. A total of 54 dolphin groups were encountered (mean size 10.0 animals, SD=5.90, range 1–30, based on 84 group size samples recorded at 60 min intervals). Dolphin group follows averaged 94 min (SD=74.3, n=54, range 2–282 min), totalling 84 h 20 min of individual photo-identification effort across 457 km. Of 5890 digital photos taken (at 18 megapixel resolution), 3141 high quality images portraying single dorsal fins were selected. The dorsal fins of 95 individuals had natural marks allowing for long-term identification. Based on the number of photos portraying marked vs. unmarked individuals, we estimated a marked proportion of 0.92. The hypothesis of population closure was rejected by the Stanley and Burnham closure test (χ2=31.34181, df=8, p=0.0012). We therefore used an open capture-recapture model (POPAN package) in program MARK 7.1 to estimate bottlenose dolphin abundance in the study area. The model yielded a population of 100 marked animals (95% C.I.=95–106), resulting in a total population of 109 (95% C.I.=101–117). We recommend continued photo-identification effort in the Northern Evoikos Gulf and contiguous waters, for longer-term status and trends analyses

Maitotoxin-induced liver cell death involving loss of cell ATP following influx of calcium

Maitotoxin, one of the most potent marine toxins known, produced cell death in cultures of rat hepatocytes with a TD50 of 80 pm at 24 hr. The cell death, as indicated by a dose- and time-dependent leakage of lactate dehydrogenase (LDH), was also associated with the leakage of [14C]adenine nucleotides from hepatocytes prelabeled with [14C]adenine. The toxic effect of maitotoxin was completely abolished by the omission of calcium from the culture medium. The cell death induced by maitotoxin increased with increasing concentrations of calcium in the medium. Treatment of hepatocytes with low concentrations of the toxin (<0.5 ng/ml) resulted in increases in 45Ca influx into the cells. At higher concentrations of maitotoxin (>1 ng/ml), the initial increase in 45Ca influx was followed by the release of the 45Ca from the cells into the medium. Since the 45Ca release paralleled the LDH leakage, the release of calcium was due to cell death. The 45Ca influx, [14C]adenine nucleotide leakage, and LDH leakage were effectively inhibited by verapamil, a calcium channel blocker. Maitotoxin also induced a time- and dose-dependent loss of ATP from hepatocytes, which preceded the [14C]adenine nucleotide and LDH leakage. Thus, it appears that the cell death resulting from maitotoxin treatment is caused by the elevated intracellular calcium, which in turn inhibits mitochondrial oxidative phosphorylation causing depletion of cell ATP. Loss of cell ATP may be the causative event in the maitotoxin-induced cell death