Band-gap structure of the spectrum of the water-wave problem in a shallow canal with a periodic family of deep pools

We consider the linear water-wave problem in a periodic channel $$\Pi ^h \subset {{\mathbb {R}}}^3$$ Π h ⊂ R 3 , which is shallow except for a periodic array of deep potholes in it. Motivated by applications to surface wave propagation phenomena, we study the band-gap structure of the essential spectrum in the linear water-wave system, which includes the spectral Steklov boundary condition posed on the free water surface. We apply methods of asymptotic analysis, where the most involved step is the construction and analysis of an appropriate boundary layer in a neighborhood of the joint of the potholes with the thin part of the channel. Consequently, the existence of a spectral gap for small enough h is proven.

Numerical Analysis of Stapes Prosthesis Constraining in the Case of Otosclerosis

In the case of otosclerosis, it has been noticed that even though there are a variety of different prostheses on the market, due to the anatomical characteristics, it is not always possible to restore excellent mobility to the ossicles and the prosthesis. On the one hand, this happens because the incus long process and the prosthesis create difficult angles. On the other hand, incus necrosis is among the most common causes of the loss of stability to the prosthesis and stapedectomy failure. The aim of this research is to suggest an improvement for stapes prosthesis stability and numerically evaluate the impact of the prosthesis constraining to its dynamical behavior. Numerical 3D models of a standard as well as a modified (adjustable angled) stapes prosthesis were created in order to achieve this aim. Consequently, the modal analysis has been performed to evaluate the mechanical behavior of the prosthesis, assuming that the piston (thick part) would be made of Teflon, and the thin part, fixated on the incus long process, would be made from titanium alloy. Finally, the numerical analysis has been conducted by changing the boundary conditions in respect of the prosthesis constraining, where the attached stapes prosthesis connects to the ossicular chain. Subsequently, there were two hypotheses raised for the prosthesis loop constraining. The first is that during the surgery, the prosthesis is perfectly crimped with certain looseness. The second is that the prosthesis is outgrown by the tissues over time and thus becomes over-constrained. Then, the analyzed standard stapes prosthesis does not fulfil its functions because of the over-constraining that develops over time. An improvement for the standard stapes prosthesis, i.e., a modified stapes prosthesis (adjustable angled), that has been proposed in this research allows avoidance of the negative effects of the over-constrained standard stapes prosthesis that appear over time. Moreover, the proposed modified prosthesis helps to regain hearing when the angle between the incus long process and prosthesis is unfavorable.

Investigation of sensitive element for pressure sensor based on bipolar piezotransistor

The article translated from Russian to English on pp. 691-693 (please, look down). The paper summarizes results of investigation of high-sensitivity MEMS pressure sensor based on a circuit containing both active and passive stress-sensitive elements: a differential amplifier utilizing two n-p-n piezotransistors and for p-type piezoresistors. A comparative analysis of a sensor utilizing this circuit with a pressure sensor based on traditional piezoresistive Wheatstone bridge and built on the same mechanical part is provided. MEMS pressure sensor with the differential amplifier (PSDA) has sensitivity of S = 0.66 mV/kPa/V, which exceeded the sensitivity of the element with piezoresistive Wheatstone bridge (PSWB) by 2.2 times. The sensitivity increase allows for the following sensor improvements: die size reduction, increase of diaphragm mechanical strength while keeping high pressure sensitivity, and simplifying requirements to external processing of the pressure sensor output signal. There are two main challenges related to the use of PSDA-based pressure sensors: strong dependence of output signal on temperature and higher than in PSWB noise reducing the dynamic range of the device to 10 3. The article describes methods of addressing these problems. The temperature dependence of sensor output signal can be minimized with help of an offset thermal compensation circuit and by eliminating metallization at the thin part of the diaphragm. The noise can be minimized by reducing the thickness of the active base region of the transistor. Circuit analysis with software NI Multisim shows that sensitivity of PSDA-based pressure sensor can be increased 2.3 times by circuit optimization.

Rate of Insufficient Ipsilateral Hamstring Graft Harvesting in Primary Anterior Cruciate Ligament Reconstruction

Anterior cruciate ligament (ACL) reconstruction, using an ipsilateral hamstring graft, may necessitate an alternative graft source if the obtained graft is insufficient with regards to length or diameter. The study aims to determine the rate of insufficient ipsilateral hamstring graft harvesting in primary ACL reconstruction. Retrospective review of 50 consecutive primary ACL reconstructions performed by a single surgeon in the United Kingdom. In 3 of 50 cases, there was insufficient ipsilateral hamstring graft harvesting and a contralateral hamstring graft was used. In two cases, this was due to premature division of the ipsilateral hamstring tendons (3/100 harvested tendons). In one case, an adequate length of semitendinosus was obtained, but its central portion was too thin. Retrospective review of preoperative magnetic resonance imaging identified the thin part of the tendon in the latter case. Insufficient ipsilateral hamstring graft harvesting is a recognized, yet unusual intraoperative complication in primary ACL reconstruction. Presurgical planning as to how to manage such complications is essential.

Formation Process of Columnar Grown (101)-Oriented Silicalite-1 Membrane and Its Separation Property for Xylene Isomer

Silicalite-1 membrane was prepared on an outer surface of a tubular α-alumina support by a secondary growth method. Changes of defect amount and crystallinity during secondary growth were carefully observed. The defect-less well-crystallized silicalite-1 membrane was obtained after 7-days crystallization at 373 K. The silicalite-1 membrane became (h0l)-orientation with increasing membrane thickness, possibly because the orientation was attributable to “evolutionally selection”. The (h0l)-oriented silicalite-1 membrane showed high p-xylene separation performance for a xylene isomer mixture (o-/m-/p-xylene = 0.4/0.4/0.4 kPa). The p-xylene permeance through the membrane was 6.52 × 10−8 mol m−2 s−1 Pa−1 with separation factors αp/o, αp/m of more than 100 at 373 K. As a result of microscopic analysis, it was suggested that a very thin part in the vicinity of surface played as effective separation layer and could contribute to high permeation performance.

Variability and parsec-scale radio structure of candidate compact symmetric objects

ABSTRACT We report results on multiepoch Very Large Array (VLA) and pc-scale Very Long Baseline Array (VLBA) observations of candidate compact symmetric objects (CSOs) from the faint sample of high-frequency peakers. New VLBA observations could resolve the radio structure in about 42 per cent of the observed sources, showing double components that may be either mini-lobes or core-jet structures. Almost all the sources monitored by the VLA show some variability on time-scale of a decade, and only one source does not show any significant variation. In 17 sources, the flux density changes randomly as it is expected in blazars, and in four sources the spectrum becomes flat in the last observing epoch, confirming that samples selected in the GHz regime are highly contaminated by beamed objects. In 16 objects, the pc-scale and variability properties are consistent with a young radio source in adiabatic expansion, with a steady decrease of the flux density in the optically thin part of the spectrum, and a flux density increase in the optically thick part. For these sources, we estimate dynamical ages between a few tens to a few hundred years. The corresponding expansion velocity is generally between 0.1c and 0.7c, similar to values found in CSOs with different approaches. The fast evolution that we observe in some CSO candidates suggests that not all the objects would become classical Fanaroff–Riley radio sources.

ALARIOSIS OF CARNIVOROUS ANIMALS IN CENTRAL RUSSIA

The spread of alariosis of fishing animals of Central Russia was clarified and a circle of host agents among mammals was identified. The material for the study was the arcasses of trade animals. The period of work was 2018–2020. Animals were studied according to the method of complete helminthological study on K.I. Skryabin (1928). The tissue form of alariosis was examined by trichinelloscopic methods. During the reporting period, 107 heads of carnivorous animals (of which 27 heads (25.2%) are considered stray domestic) extracted in the territory of the Ryazan, Vladimir and Moscow regions. Of the Canidae family, 54 heads have undergone helminthological examination (29 foxes, 17 domestic dogs, 7 raccoon dogs, and 1 wolf). Of the cat (Felidae), 11 heads have been studied (domestic cats – 10, lynx – 1). Martens animals (Mustelinae) have been studied 42 heads (forest мartens – 19, stone мartens – 6, river otter – 4, ermines – 7, badgers – 2, аmerican mink – 4). Adult trematodes have been identified in 37 carnivorous animals (34.6%) in the thin part of the intestine. Canidae animals representing trade species (fox, raccoon dog, wolf) are 100% infected with the agent of alariosis. The intensity invasion of fox was 4–250 copies per head, raccoon dogs – 11–284, wolf – 84. The larval form of the agent was recorded in one fox (3.5%), 2 forest мartens (10.5%) and one аmerican mink (25.0%). Mesocercaries of trematodes were localized in a transparent capsule in lung parenchyma, in diaphragm muscle tissue, in esophageal muscle tissue.

A two-sided but significantly beamed jet in the supercritical accretion quasar IRAS F11119+3257

ABSTRACT Highly accreting quasars are quite luminous in the X-ray and optical regimes; while, they tend to become radio quiet and have optically thin radio spectra. Among the known quasars, IRAS F11119+3257 is a supercritical accretion source because it has a bolometric luminosity slightly above the Eddington limit and extremely powerful X-ray outflows. To probe its radio structure, we investigated its radio spectrum between 0.15 and 96.15 GHz and performed very-long-baseline interferometric (VLBI) observations with the European VLBI Network (EVN) at 1.66 and 4.93 GHz. The deep EVN image at 1.66 GHz shows a two-sided jet with a projected separation about 200 pc and a very high flux density ratio of about 290. Together with the best-fitting value of the integrated spectral index of −1.31 ± 0.02 in the optically thin part, we infer that the approaching jet has an intrinsic speed at least 0.57 times of the light speed. This is a new record among the known all kinds of super-Eddington accreting sources and unlikely accelerated by the radiation pressure in a certain models. We propose a scenario in which IRAS F11119+3257 is an unusual compact symmetric object with a small jet viewing angle and a radio spectrum peaking at 0.53 ± 0.06 GHz mainly due to the synchrotron self-absorption.