Foreshock and aftershock sequences of the Cremasta earthquake and their relation to the waterloading of the Cremasta artificial lake

Investigation of the time and magnitude distributionof the fore- and aftershocks of the Cremasta lake earthquake which occurredon February 5, 1966 is made. The deformation characteristics andspatial distribution of these shocks is also studied. Strong evidence is presentedthat the foreshocks and the main shock have been triggered by thewaterloading of the Cremasta artificial lake

Variability of physical factors relevant to fisheries production in the Mediterranean Sea, North Sea and Baltic Sea

Recent publications have shown that river runoff and wind mixing are two major environmental factors affecting productivity of fish populations in subtropical and tropical areas, as opposed to water temperature in colder waters. In the present paper, we compare the variability of seawater temperature, river runoff and wind mixing in three different seas: a subtropical sea (the Mediterranean) and two cold seas (the North Sea and the Baltic). Temperature variability decreased from colder to warmer areas. The highest temporal variability in the river runoff corresponded to rivers flowing into the Mediterranean, and the lowest corresponded to rivers flowing into the North Sea and the Baltic Sea. The variability in the wind mixing index (cube of the wind speed) depended on the area under consideration, and attained maximum values in the Cap Béar station (northwestern Mediterranean). The effect of these regional variability differences in environmental factors on fisheries production is briefly discussed.Investigaciones recientes demuestran que las descargas fluviales y los vientos son factores ambientales clave para la productividad de las poblaciones explotadas en zonas subtropicales y tropicales, mientras que en mares fríos la temperatura del agua constituye el factor ambiental más importante para la productividad pesquera. Este estudio compara las diferencias geográficas en la variabilidad temporal de tres factores físicos (temperatura del agua, aportes fluviales y velocidad del viento) en un mar subtropical (Mediterráneo) y dos mares fríos (Mar del Norte y Báltico). La variabilidad temporal de la temperatura del agua es mayor en los dos mares fríos que en el subtropical. Así mismo, los ríos que desembocan en el Mediterráneo presentan mayor variabilidad temporal en cuanto a los aportes fluviales que los ríos que desembocan en el Mar del Norte y el mar Báltico. La variabilidad temporal en el índice de mezcla del viento (velocidad del viento al cubo) es distinta según la zona que se considere, y es máxima en la estación de Cap Béar (Mediterráneo noroccidental). Finalmente, se discuten los efectos de esta variabilidad ambiental geográfica sobre las poblaciones explotadas.Instituto Español de Oceanografí

Proučavanje seizmičkog zoniranja na području Grčke na osnovi magnitude najbolje opažljivog potresa

The Greek seismicity file developed by Makropoulos and Burton (1981) for earthquakes up to 1978 and extended up to 1983 (Makropoulos et al., 1986), is examined in terms of magnitude frequency using Gumbel’s third type asymptotic distribution of extreme values. The forecasting parameters are obtained by subdividing Greek seismicity in a cellular manner. Combination of the Gumbel III earthquake occurrence statistics for each cell with acceleration attenuation law leads to perceptibility curves which give the probability of perceiving specific acceleration levels from each earthquake magnitude up to local upper bound magnitude w. These curves show a peak probability which occurs at similar magnitudes defined as the “most perceptible” earthquake. The range of these “most perceptible” earthquake magnitudes is for an Ms of about 5.3 to 7.2. The results are presented as contouring maps for two average depths of 10 km and 20 km respectively. The features of the contoured perceptibility maps are compatible with existing hazard maps of Greece based on different approaches. This, coupled with the fact that these values may be used as a criterion for choosing engineering design time histories, shows the usefulness of the method for seismic zoning problems

Ballistic thermal phonons traversing nanocrystalline domains in oriented polyethylene

Thermally conductive polymer crystals are of both fundamental and practical interest for their high thermal conductivity that exceeds that of many metals. In particular, polyethylene fibers and oriented films with uniaxial thermal conductivity exceeding 50 W⋅m^(-1)⋅K^(-1) have been reported recently, stimulating interest into the underlying microscopic thermal transport processes. While ab initio calculations have provided insight into microscopic phonon properties for perfect crystals, such properties of actual samples have remained experimentally inaccessible. Here, we report the direct observation of thermal phonons with mean free paths up to 200 nm in semicrystalline polyethylene films using transient grating spectroscopy. Many of the mean free paths substantially exceed the crystalline domain sizes measured using small-angle X-ray scattering, indicating that thermal phonons propagate ballistically within and across the nanocrystalline domains; those transmitting across domain boundaries contribute nearly one-third of the thermal conductivity. Our work provides a direct determination of thermal phonon propagation lengths in molecular solids, yielding insights into the microscopic origins of their high thermal conductivity

Ballistic thermal phonons traversing nanocrystalline domains in oriented polyethylene

Thermally conductive polymer crystals are of both fundamental and practical interest for their high thermal conductivity that exceeds that of many metals. In particular, polyethylene fibers and oriented films with uniaxial thermal conductivity exceeding 50 Wm−1K−1 have been reported recently, stimulating interest into the underlying microscopic thermal transport processes. While ab-initio calculations have provided insight into microscopic phonon properties for perfect crystals, such properties of actual samples have remained experimentally inaccessible. Here, we report the direct observation of thermal phonons with mean free paths up to 200 nm in semicrystalline polyethylene films using transient grating spectroscopy. Many of the mean free paths substantially exceed the crystalline domain sizes measured using small-angle x-ray scattering, indicating that thermal phonons propagate ballistically within and across the nano-crystalline domains, with those transmitting across domain boundaries contributing nearly a third of the thermal conductivity. Our work provides the first direct determination of thermal phonon propagation lengths in molecular solids, providing insights into the microscopic origins of their high thermal conductivity

Almost a spider: a 305-million-year-old fossil arachnid and spider origins

Spiders are an important animal group, with a long history. Details of their origins remain limited, with little knowledge of their stem group, and no insights into the sequence of character acquisition during spider evolution. We describe a new fossil arachnid, Idmonarachne brasieri gen. et sp. nov. from the Late Carboniferous (Stephanian, ca 305–299 Ma) of Montceau-les-Mines, France. It is three-dimensionally preserved within a siderite concretion, allowing both laboratory- and synchrotron-based phase-contrast computed tomography reconstruction. The latter is a first for siderite-hosted fossils and has allowed us to investigate fine anatomical details. Although distinctly spider-like in habitus, this remarkable fossil lacks a key diagnostic character of Araneae: spinnerets on the underside of the opisthosoma. It also lacks a flagelliform telson found in the recently recognized, spider-related, Devonian–Permian Uraraneida. Cladistic analysis resolves our new fossil as sister group to the spiders: the spider stem-group comprises the uraraneids and I. brasieri. While we are unable to demonstrate the presence of spigots in this fossil, the recovered phylogeny suggests the earliest character to evolve on the spider stem-group is the secretion of silk. This would have been followed by the loss of a flagelliform telson, and then the ability to spin silk using spinnerets. This last innovation defines the true spiders, significantly post-dates the origins of silk, and may be a key to the group's success. The Montceau-les-Mines locality has previously yielded a mesothele spider (with spinnerets). Evidently, Late Palaeozoic spiders lived alongside Palaeozoic arachnid grades which approached the spider condition, but did not express the full suite of crown-group autapomorphies

Advancing Intra-operative Precision: Dynamic Data-Driven Non-Rigid Registration for Enhanced Brain Tumor Resection in Image-Guided Neurosurgery

During neurosurgery, medical images of the brain are used to locate tumors and critical structures, but brain tissue shifts make pre-operative images unreliable for accurate removal of tumors. Intra-operative imaging can track these deformations but is not a substitute for pre-operative data. To address this, we use Dynamic Data-Driven Non-Rigid Registration (NRR), a complex and time-consuming image processing operation that adjusts the pre-operative image data to account for intra-operative brain shift. Our review explores a specific NRR method for registering brain MRI during image-guided neurosurgery and examines various strategies for improving the accuracy and speed of the NRR method. We demonstrate that our implementation enables NRR results to be delivered within clinical time constraints while leveraging Distributed Computing and Machine Learning to enhance registration accuracy by identifying optimal parameters for the NRR method. Additionally, we highlight challenges associated with its use in the operating room