3D discrete element modeling of concrete: study of the rolling resistance effects on the macroscopic constitutive behavior

The Discrete Element Method (DEM) is appropriate for modeling granular materials [14] but also cohesive materials as concrete when submitted to a severe loading such an impact leading to fractures or fragmentation in the continuum [1, 5, 6, 8]. Contrarily to granular materials, the macroscopic constitutive behavior of a cohesive material is not directly linked to contact interactions between the rigid Discrete Elements (DE) and interaction laws are then defined between DE surrounding each DE. Spherical DE are used because the contact detection is easy to implement and the computation time is reduced in comparison with the use of 3D DE with a more complex shape. The element size is variable and the assembly is disordered to prevent preferential cleavage planes. The purpose of this paper is to highlight the influence of DE rotations on the macroscopic non-linear quasi-static behavior of concrete. Classically, the interactions between DE are modeled by spring-like interactions based on displacements and rotation velocities of DE are only controlled by tangential forces perpendicular to the line linking the two sphere centroids. The disadvantage of this modeling with only spring-like interactions based on displacements is that excessive rolling occurs under shear, therefore the macroscopic behavior of concrete is too brittle. To overcome this problem a non linear Moment Transfer Law (MTL) is introduced to add a rolling resistance to elements. This solution has no influence on the calculation cost and allows a more accurate macroscopic representation of concrete behavior. The identification process of material parameters is given and simulations of tests performed on concrete samples are shown

Every latin hypercube of order 5 has transversals

We prove that for all n>1 every latin n-dimensional cube of order 5 has transversals. We find all 123 paratopy classes of layer-latin cubes of order 5 with no transversals. For each $n\geq 3$ and $q\geq 3$ we construct a (2q-2)-layer latin n-dimensional cuboid with no transversals. Moreover, we find all paratopy classes of nonextendible and noncompletable latin cuboids of order 5.Comment: Supplementary data https://zenodo.org/records/1020402

Changes of the body functions during long-term hypokinesia

Prolonged hypokinesis (100-170 days) studied in 2000 rats kept in cages limiting their mobility provoked considerable changes in the gaseous and energetic metabolism: an elevation of the total gaseous metabolism and of the rate of O2 requirement by the muscles (in the late periods of hypokinesis) and a change in the intensity of tissue respiration of the liver and myocardium. There also proved to be a reduction in the level of phosphorylation and separation of oxidative phosphorylation in the myocardium, liver, and partially in the skeletal muscle. Prolonged hypokinesia led to changes in tissue metabolism: a disturbance of development of the animals, a marked delay and an increase in the weight of the organism and the muscular system, and disturbances of the mineral and protein metabolism. Prolonged hypokinesis also lead to exhaustion of the hypothalamus-hypophysis-adrenal cortex system

ПОСЛЕОПЕРАЦИОННАЯ АНАЛЬГЕЗИЯ ОПИОИДАМИ И БИОПСИХОСОЦИАЛЬНАЯ МОДЕЛЬ БОЛИ

The objective of the work is to assess the implementation advisability of the biopsychosocial model of pain during the postoperative opioid analgesia. It was established that under the similar interventions in terms of severity and medication doses the bodily pain with the patients vary by a wide margin. The diagnosed differences may be conditional upon the biological, psychological and social factors, so the biopsychosocial approach is the promising direction to improve the postoperative opioid analgesia efficiency. Цель работы - оценка целесообразности имплементации биопсихосоциальной модели боли при проведении послеоперационной анальгезии опиоидами. Установлено, что при одинаковых по тяжести вмешательствах и дозах препаратов интенсивность боли у пациентов значительно варьирует. Выявленные отличия могут быть обусловлены влиянием биологических, психологических и социальных факторов, поэтому биопсихосоциальный подход является перспективным направлением для повышения эффективности послеоперационной анальгезии опиоидами

Дополнительное пероральное питание в составе нутритивной поддержки в онкохирургии

The objective is to present current data about the role of oral nutrition supplements (ONS) in cancer surgery.  Results: this type of nutritional support should be considered as an integral part of the enhanced recovery after surgery.  Despite the apparent simplicity of prescription, it should be treated as one of the types of medical nutrition with its own indications, providing for the individual selection of specific formulas and evaluation of effectiveness. For the initial assessment of cancer patient nutritional status, European Society for Medical Oncology scale (ESMO, 2008) is the most appropriate. ONS should be combined with diet recommendations and physical activity maintaining.  Inability to provide with ONS > 60% of the daily energy requirements within 5–7 days, should be considered as an indication to start artificial nutrition – enteral and/or parenteral. Цель: представить современные данные о роли дополнительного перорального питания (ДПП) в онкохирургии.Результаты: ДПП следует рассматривать как неотъемлемую часть ускоренной реабилитации хирургических пациентов. Несмотря на кажущуюся простоту назначения, к нему следует относиться как к одному из видов лечебного питания, имеющему свои показания, предусматривающему индивидуальный подбор конкретной смеси и оценку эффективности. С целью начальной оценки нутритивного статуса онкологического пациента наиболее приемлемой является шкала Европейского общества химиотерапевтов (ESMO, 2008). ДПП следует сочетать с диетическими рекомендациями и поддержанием физической активности. Невозможность в течение 5‒7 сут обеспечить с помощью ДПП > 60% от суточных энергетических потребностей должна рассматриваться как показание к началу искусственного питания – энтерального и/или парентерального.

Skew-self-adjoint discrete and continuous Dirac type systems: inverse problems and Borg-Marchenko theorems

New formulas on the inverse problem for the continuous skew-self-adjoint Dirac type system are obtained. For the discrete skew-self-adjoint Dirac type system the solution of a general type inverse spectral problem is also derived in terms of the Weyl functions. The description of the Weyl functions on the interval is given. Borg-Marchenko type uniqueness theorems are derived for both discrete and continuous non-self-adjoint systems too

Safety and feasibility of robotic-assisted drainage of symptomatic pancreatic pseudocysts: A case-series analysis (with video)

The surgical treatment of pancreatic pseudocysts (PPs) in patients who fail nonoperative management has evolved from aggressive open to a minimally invasive approach. The application of robotic surgery in this setting is scarcely reported. The aim of this study is to analyze the safety and feasibility of the robotic approach to pancreatic pseudocyst drainage. A single centre retrospective review of consecutive patients undergoing robotic-assisted pancreatic pseudocyst surgeries in an academic tertiary institution was performed. There were 14 patients studied, of whom 10 underwent cystogastrostomy and 4 Roux-En-Y cystojejunostomy. Eight patients had gallstone pancreatitis and 3 patients alcoholic pancreatitis. The mean size of cyst was 8.9±1cm and 57.1% located at the pancreatic body. The overall operative time of the procedure was 135±34 minutes. There were no open conversions. The overall success rate was 92.8%, while the primary success rate 85.7%. The major morbidity rate was 14.3% and there was no 30-day mortality. The mean post-operative hospital stay was 7±3 days with one recurrence of the pancreatic pseudocyst on follow-up requiring endoscopic drainage without further recurrence. The robotic approach for the drainage of symptomatic pancreatic pseudocyst is safe and feasible and can be considered as a viable modality for operative intervention in well-selected patient

Using the Landsat data archive to assess long-term regional forest dynamics assessment in Eastern Europe, 1985-2012

Abstract. Dramatic political and economic changes in Eastern European countries following the dissolution of the “Eastern Bloc” and the collapse of the Soviet Union greatly affected land-cover and land-use trends. In particular, changes in forest cover dynamics may be attributed to the collapse of the planned economy, agricultural land abandonment, economy liberalization, and market conditions. However, changes in forest cover are hard to quantify given inconsistent forest statistics collected by different countries over the last 30 years. The objective of our research was to consistently quantify forest cover change across Eastern Europe from 1985 until 2012 using the complete Landsat data archive. We developed an algorithm for processing imagery from different Landsat platforms and sensors (TM and ETM+), aggregating these images into a common set of multi-temporal metrics, and mapping annual gross forest cover loss and decadal gross forest cover gain. Our results show that forest cover area increased from 1985 to 2012 by 4.7% across the region. Average annual gross forest cover loss was 0.41% of total forest cover area, with a statistically significant increase from 1985 to 2012. Most forest disturbance recovered fast, with only 12% of the areas of forest loss prior to 1995 not being recovered by 2012. Timber harvesting was the main cause of forest loss. Logging area declined after the collapse of socialism in the late 1980s, increased in the early 2000s, and decreased in most countries after 2007 due to the global economic crisis. By 2012, Central and Baltic Eastern European countries showed higher logging rates compared to their Western neighbours. Comparing our results with official forest cover and change estimates showed agreement in total forest area for year 2010, but with substantial disagreement between Landsat-based and official net forest cover area change. Landsat-based logging areas exhibit strong relationship with reported roundwood production at national scale. Our results allow national and sub-national level analysis of forest cover extent, change, and logging intensity and are available on-line as a baseline for further analyses of forest dynamics and its drivers

Differential neutron energy spectra measured on spacecraft low Earth orbit

Two methods for measuring neutrons in the range from thermal energies to dozens of MeV were used. In the first method, alpha-particles emitted from the (sup 6) Li(n.x)T reaction are detected with the help of plastic nuclear track detectors, yielding results on thermal and resonance neutrons. Also, fission foils are used to detect fast neutrons. In the second method, fast neutrons are recorded by nuclear photographic emulsions (NPE). The results of measurements on board various satellites are presented. The neutron flux density does not appear to correlate clearly with orbital parameters. Up to 50% of neutrons are due to albedo neutrons from the atmosphere while the fluxes inside the satellites are 15-20% higher than those on the outside. Estimates show that the neutron contribution to the total equivalent radiation dose reaches 20-30%

Quantum Phase Shift in Chern-Simons Modified Gravity

Using a unified approach of optical-mechanical analogy in a semiclassical formula, we evaluate the effect of Chern-Simons modified gravity on the quantum phase shift of de Broglie waves in neutron interferometry. The phase shift calculated here reveals, in a single equation, a combination of effects coming from Newtonian gravity, inertial forces, Schwarzschild and Chern-Simons modified gravity. However the last two effects, though new, turn out to be too tiny to be observed, and hence only of academic interest at present. The approximations, wherever used, as well as the drawbacks of the non-dynamical approach are clearly indicated.Comment: 16 pages, minor errors corrected. Accepted for publication in Phys. Rev.