Small Is Not Always Beautiful

Peer-to-peer content distribution systems have been enjoying great popularity, and are now gaining momentum as a means of disseminating video streams over the Internet. In many of these protocols, including the popular BitTorrent, content is split into mostly fixed-size pieces, allowing a client to download data from many peers simultaneously. This makes piece size potentially critical for performance. However, previous research efforts have largely overlooked this parameter, opting to focus on others instead. This paper presents the results of real experiments with varying piece sizes on a controlled BitTorrent testbed. We demonstrate that this parameter is indeed critical, as it determines the degree of parallelism in the system, and we investigate optimal piece sizes for distributing small and large content. We also pinpoint a related design trade-off, and explain how BitTorrent's choice of dividing pieces into subpieces attempts to address it

Identification of Myotropic Neuropeptides from the Brain and Corpus Cardiacum-Corpus Allatum Complex of the Beetle, Zophobas atratus

The neuropeptide profiles of the two major neuro-endocrinological organs, brain and retrocerebral complex corpus cardiacum-corpus allatum (CC/CA) of adult beetles, Zophobas atratus Fabricius (Coleoptera:Tenebrionidae) were analyzed by a combination of high performance liquid chromatography (HPLC) and matrix-assisted laser desorption ionization time of flight tandem mass spectrometry (MALDI TOF/TOF MS). The homological semi-isolated heart bioassay was used to screen HPLC fractions for myotropic activity in tissues, revealing several cardiostimulatory and cardioinhibitory factors from both the brain and CC/CA. Analysis of HPLC fractions by MALDI-TOF MS identified seven mass ions that could be assigned to other known peptides: leucomyosuppressin (LMS), Tribolium castaneum pyrokinin 2, sulfakinin 1, myoinhibitory peptide 4, a truncated NVP-like peptide, Tenebrio molitor AKH and crustacean cardioactive peptide. In addition, two novel peptides, myosuppressin (pEDVEHVFLRFa), which differs from LMS by one amino acid (E for D at position 4) and pyrokinin-like peptide (LPHYTPRLa) were also identified. To establish cardioactive properties of some of the identified peptides, chemical synthesis was carried out and their activities were tested using the heart bioassay

New physiological activities of myosuppressin, sulfakinin and NVP-like peptide in Zophobas atratus beetle

Three neuropeptides Zopat-MS-2 (pEDVDHVFLRFa), Zopat-SK-1 (pETSDDYGHLRFa) and Zopat-NVPL-4trunc. (GRWGGFA), recently isolated from the neuroendocrine system of the Zophobas atratus beetle, were tested for their myotropic and hyperglycaemic activities in this species. These peptides exerted differentiated dose-dependent and tissue specific physiological effects. Zopat-MS-2 inhibited contractions of the isolated heart, ejaculatory duct, oviduct and hindgut of adult beetles and induced bimodal effects in the heart contractile activity of pupae in vivo. It also increased the haemolymph free sugar level in larvae of this species, apart from myotropic activity. Zopat-SK-1 showed myostimulatory action on the isolated hindgut of the adult beetles, but it decreased contractions of the heart, ejaculatory duct and oviduct. Injections of this peptide at a dose of 2 μg also caused delayed cardioinhibitory effects on the heartbeat of the pupae. Together with the ability to increase free sugar level in the haemolymph of larvae these were new physiological activities of sulfakinins in insects. Zopat-NVPL-4trunc. inhibited the muscle contractions of the two organs: hindgut and ejaculatory duct but it was inactive on the oviduct and the heart of the adult beetles. This peptide also increased free sugar level concentration in the haemolymph of Z. atratus larvae. These physiological actions are the first biological activities discovered for this group of the insect peptides. The present work showed pleiotropic activity of three neuropeptides and indicates that the visceral muscle contractions and the haemolymph sugar homeostasis in Z. atratus are regulated by complex mechanisms

Diagnostic performance of point-of-use ultrasound of resuscitation outcomes: A systematic review and meta-analysis of 3265 patients

Background: Echocardiography in the setting of resuscitation can provide information as to the cause of the cardiac arrest, as well as indicators of futility. This systematic review and meta-analysis were performed to determine the value of point-of-care ultrasonography (PoCUS) in the assessment of survival for adult patients with cardiac arrest. Methods: This meta-analysis was performed in adherence to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. PubMed, EMBASE, Web of Science, Cochrane have been searched from databases inception until March 2nd 2021. The search was limited to adult patients with cardiac arrest and without publication dates or country restrictions. Papers were chosen if they met the required criteria relating to the sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of this diagnostic technique concerning resuscitation outcomes. Results: This systematic review identified 20 studies. Overall, for survival to hospital discharge, PoCUS was 6.2% sensitivity (95% confidence interval [CI] 4.7% to 8.0%) and 2.1% specific (95% CI 0.8–4.2%). PoCUS sensitivity and specificity for return of spontaneous circulation were 23.8% (95% CI 21.4–26.4%) and 50.7% (95% CI 45.8–55.7%) respectively, and for survival to admission 13.8% (95% CI 12.2–15.5%) and 20.1% (95% CI 16.2–24.3%), respectively. Conclusions: The results do not allow unambiguous recommendation of PoCUS as a predictor of resuscitation outcomes and further studies based on a large number of patients with full standardization of operators, their training and procedures performed were necessary

Physical and dynamical properties of the unusual V-type asteroid (2579) Spartacus

Context. Asteroid (2579) Spartacus is a small V-type object located in the inner main belt. This object shows spectral characteristics unusual for typical Vestoids, which may indicate an origin deeper than average within Vesta or an origin from an altogether different parent body. Aims. Our main goal is to study the origin of Spartacus. We derive the spin of Spartacus and a convex shape model of Spartacus in order to increase the knowledge of the body's physical properties. The rotational parameters are then used to investigate dynamical evolution of the object as well as to distinguish regions sampled by spectral observations to determine whether its surface displays heterogeneity. Methods. We collected lightcurves available from the literature (oppositions of 2009, 2012) and obtained additional photometric observations at various telescopes in 2016, 2017, and 2018. We used the lightcurve inversion method to derive a spin and convex shape model. We have collected spectral observations over two rotational periods of Spartacus and determined its spectral parameters using the modified Gaussian model (MGM). We then dynamically integrated the orbital elements of Spartacus, taking into account existing information, including its thermal properties, size and the derived spin axis orientation. Results. We find two models for (2579) Spartacus: (a) lambda = 312 degrees +/- 5 degrees, beta = -57 degrees +/- 5 degrees and (b) lambda = 113 degrees +/- 5 degrees, beta = -60 degrees +/- 5 degrees both retrograde. We find that the drift direction for Spartacus is consistent with separation from Vesta, and after a backward integration of 1 Gyr the asteroid reaches the boundary of the family. We did not observe spectral variations with rotation, thus the body most likely has a homogeneous surface. Additionally, new spectral analysis indicates that the 1.0 and 2.0 mu m band centers are within ranges that are typical for Vestoids while the area ratio of these bands is about half that of typical Vestoids. Conclusions. The asteroid (2579) Spartacus is in retrograde rotation and has a drift direction consistent with an origin from Vesta. The revised spectral band centers are within ranges typical for Vestoids, while band area ratio (BAR) is unusually low compared to that of other V-types. The dynamical model shows that the asteroid could have migrated to its current location from the edges of the Vesta family within 1 Gyr, but an origin from an earlier impact on Vesta could also be plausible.Peer reviewe

Automatic Classification of Cardiac Disease State from Medical Image Data

This thesis presents work towards a comprehensive set of methods to extract quantitative shape features and infarct information from cardiac magnetic resonance imaging data to enable classification of a heart disease state in terms of arrhythmia occurrence. The aim of the first part of this work is to process the images and convert the output to a computational domain usable for analysis / modelling. A comprehensive pipeline is constructed, to go from late gadolinium enhanced cardiac magnetic resonance images to numerical bi-ventricle meshes. The goal is to utilize the tools that are available open-source, in order to encourage the use by other researchers. A method of using mathematical currents to describe the meshes is employed to define the population mean shape and patient-specific shape characteristics. The resulting features are decomposed using linear and non-linear algorithms to extract the relevant information. The second part of this thesis concerns the application of machine learning algorithms to the set of subjects pre-processed with the pipeline. The main objective is to reduce the high variance imposed by the small size of available data. The unsupervised and supervised algorithms are used to search for patterns in the data and classify the myocardial infarction patients according to the presence of ventricular fibrillation during the first ST-elevation myocardial infarction to provide valuable insights into the pathophysiology. The single classifiers are combined using a variety of ensemble methods. Finally, a multiple kernel method which integrates multiple modalities is presented. This method takes advantage of the infarct information embedded in the late gadolinium enhanced cardiac magnetic resonance images. The classification of myocardial infarction patients used in the thesis is an example problem of using machine learning for clinical support. The techniques presented in this thesis can be used to analyze and classify any heart disease manifesting with ventricular remodelling and / or infarct development

Proxies for heat fluxes to the Arctic Ocean through Fram Strait

Oceanic fluxes through Fram Strait may significantly contribute to climate variations in the Arctic. However, their observations are difficult. Here, a 26-year numerical model simulation is used to derive oceanic proxies for interannual variability in heat fluxes through Fram Strait. It is found that variability in the cross-slope gradient of sea surface height (SSH) across the West Spitsbergen Current (WSC) can explain about 90% of the variance of winter and annual mean volume transports of Atlantic water at 79°N. Given the strong covariance between the simulated heat flux in the slope current along Svalbard and the corresponding volume transport, variability of the SSH gradient across the WSC is also found to account for about 80% of the variance of heat flux associated with the northward flow through Fram Strait. Moreover, variations in the SSH gradient across the Arctic Slope Current (ASC) northeast of Svalbard at 31°E explain about 85% of the variance of heat flux there and about 80% of the variance of the net heat flux upstream through Fram Strait. Finally, about 85% and 75% of the variance of the net heat flux through Fram Strait is associated with anomalies of the eastward volume transport and depth-averaged core velocity in the ASC, respectively. These relations indicate that monitoring of the flow in the ASC, even with a single current meter mooring, or of the SSH gradient across this current derived from either in situ or remote measurements may provide useful proxies for the heat import to the Arctic Ocean

Neuropeptidomes of Tenebrio molitor L. and Zophobas atratus Fab. (Coleoptera, Polyphaga: Tenebrionidae)

Neuropeptides are signaling molecules that regulate almost all physiological processes in animals. Around 50 different genes for neuropeptides have been described in insects. In Coleoptera, which is the largest insect order based on numbers of described species, knowledge about neuropeptides and protein hormones is still limited to a few species. Here, we analyze the neuropeptidomes of two closely related tenebrionid beetles: Tenebrio molitor and Zophobas atratus-both of which are model species in physiological and pharmacological research. We combined transcriptomic and mass spectrometry analyses of the central nervous system to identify neuropeptides and neuropeptide-like and protein hormones. Several precursors were identified in T. molitor and Z. atratus, of which 50 and 40, respectively, were confirmed by mass spectrometry. This study provides the basis for further functional studies of neuropeptides as well as for the design of environmentally friendly and species specific peptidomimetics to be used as biopesticides. Furthermore, since T. molitor has become accepted by the European Food Safety Authority as a novel food, a deeper knowledge of the neuropeptidome of this species will prove useful for optimizing production programs at an industrial scale