Sharp Constriction Research Articles

Assessing the feasibility of protein sequencing using biological nanopores

The nanopore technology offers extraordinary long reads of DNA and RNA sequence by measuring ionic current signals produced by nucleic acid translocation through a biological nanopore. The key to success of the nanopore sequencing method is stepwise translocation of the nucleic acid realized by means of a DNA processing motor and the sharp constriction of the biological nanopore that enables detection of subtle differences among the nucleotides. Here, we use all-atom molecular dynamics simulations to explore the ability of biological nanopores to distinguish amino acids by means of an ionic current blockade.

Pupil response to quality and content transitions in videos

Real-time human eye recognition and tracking systems with human-computer interaction mechanism are being adopted to advance user experience in smart devices and consumer electronic systems. Eye tracking systems measure eye gaze and pupil response non-intrusively. This paper presents an analysis of pupil response to video structure and content. A consumer device that can assess user response to a video can provide better experiences with approaches such as real-time content adaptation. The first set of experiments involved presenting different video content to subjects and measuring eye response with an eye tracker. Results show that pupil constrictions and magnitude of constrictions vary with content. Significant changes in video and scene cuts led to sharp constrictions. User response to videos can provide insights that can improve subjective quality assessment metrics. This paper also presents an analysis of the pupillary response to quality changes in videos with the second set of experiments. The results of the tests show pupil constrictions for noticeable changes in perceived quality. Using real-time eye tracking systems for video analysis and quality evaluation can open a new class of applications for consumer electronic systems.

Morphological and molecular characterization of Tylencholaimellus persicus sp. n. (Dorylaimida: Tylencholaimellidae) from Iran.

Tylencholaimellus persicus sp. n. is described and illustrated based on morphological and molecular characters. The new species is characterized by its 613-885 μm long body, expanded lip region separated from body contour by a sharp constriction, forming a large disk-like structure, odontostyle and odontophore respectively 12-14 and 6.5-8.0 μm long, female genital system mono-opisthodelphic with relatively long anterior uterine sac (AUS; 50-80 μm in length), position of vulva relative to the body length (V = 36.5-41.5), broadly rounded tail, abundant males in population with 22-25 μm long spicules and one ventromedian copulatory supplement. The new species is compared with five known species of the genus that have a perioral disc, rounded tail and AUS: T. coronatus, T. incertus, T. montanus, T. ozarkensis and T. projectus. Compared to these five species, the new species has an expanded lip region separated from body contour by a sharp constriction, but can further be separated by a combination of morphological and morphometric characters such as odontostyle length, tail shape, differences in ratios c´ and V and male characters. Because of having similar general morphology, the new species was also compared with a species of genus Margollus, M. bokanicus, and the differences between the two species are discussed. In addition to morphological and morphometric data, molecular phylogenetic analyses were performed using partial sequences of the 18S SSU and 28S LSU D2/D3 rDNA segments, in which the new species forms a clade with four species/isolates of Tylencholaimellus in the SSU tree and one isolate of Tylencholaimus in the LSU tree using Bayesian inference (BI).

Propagation of neutron spherical waves through a thick, vibrating Ge single crystal

The results of experimental and theoretical studies into the influence of ultrasound on the propagation of neutron waves in a thick Ge crystal are presented. The neutron intensity profiles were measured for the case of Laue diffraction inside the Borrmann fan. At low amplitudes of ultrasonic waves interference effects (diffraction intensity beatings) were observed. The observations were possible because of the uniform acoustic-field distribution through the whole bulk of the crystal. As distinct from the classical Shull experiments, wide analysing slits or position-sensitive detectors were used. To explain the results obtained, a modified theory for the spatial distribution of neutron diffraction intensities in the presence of acoustic excitation of the crystal is proposed. A good agreement between experiment and theory is obtained. At high amplitudes of ultrasonic waves the transition to kinematic scattering was not observed, despite the large strains in the crystalline lattice created by ultrasound. This could be connected with the formation of a superlattice having a standing wave period. A strong rise in the diffraction intensity and a sharp constriction of the neutron beam at the centre of the Borrmann fan were observed. This new effect could be used for the creation of ultrasound-controlled monochromators.

Description of Dorylaimoides alborzicus sp. n. (Dorylaimida: Nematoda) from Iran, with updated compendium and key to the species of Dorylaimoides

Dorylaimoides alborzicus sp. n. is described. Characteristics of the new species include a lip region separated from the rest of body by a sharp constriction, 1.1–1.3 mm long body, 10–11 µm long odontostyle dorsal line and 8–10 µm long odontostyle ventral line, 15–16 µm long arcuate odontophore, anterior uterine sac 37–61 µm long (1.1–1.7 times corresponding body width), female tail straight to ventrally bent, elongate conoid with rounded terminus and 46–62 µm long and males with 31–35 µm long spicules, 5–6 ventromedian supplements and ventrally bent tail, 39–60 µm long. An updated identification key to all the valid species of Dorylaimoides, as well as a table of data for the species not included in the study by Peña Santiago and Peralta (1997b) is given.

Impact of channel constrictions on the formation of multiple tunnel junctions in heavily doped silicon single electron transistors

This paper reports the study of the uncontrolled multiple tunnel junctions (MTJs) induced by the random dopants in heavily doped silicon single electron transistors (SETs). The SETs are fabricated by making dual lateral constrictions in the narrow doped silicon channel formed on a silicon on insulator substrate. The doped SETs with relatively long constriction regions invariably exhibit the MTJ characteristics. The influence of the MTJs is suppressed by tuning the Fermi level in the constriction region. Finally, we show that the formation of uncontrolled MTJs can be avoided by making extremely sharp constrictions.

Pakistan’s Macroeconomic Situation

As a result of policy inaction in addressing structural issues over a protracted period and a wrong set of economic priorities followed over the past several years, Pakistan’s economy faces a grave set of challenges. Among the many issues, which range from high inflation to power deficits and water stress, the most immediate and pressing is the need to restore fiscal order. While pressure on the coalition government to reduce the economic hardship of the electorate is understandably intense, the policy response needs to balance the alleviation of palpable hardship in the short term, with the ability to provide sustained benefits over the longer term. Given the sharp constriction in available fiscal space, adopting a policy course in the short run that raises expectations of “relief” may not be wise, in either political or economic terms. In the longer term, however, it is a misconception to view the available choices in purely binary terms, i.e. that “macroeconomic stability” (a much-maligned term, loath to politicians not just in Pakistan) is mutually exclusive to “pro-poor” agendas. Raising revenues by broadening the tax base meaningfully, in conjunction with rationalizing bloated government/public sector expenditures can free fiscal resources, which can be diverted to targeted subsidy programs. Ignoring macroeconomic stability, on the other hand, will eventually also undermine the ability of the government to influence economic growth, as growing fiscal and monetary constraints limit its ability to run appropriate policies.

Wartime Paris, cirrhosis mortality, and the ceteris paribus assumption.

This article critiques the ceteris paribus assumption, which tacitly sustains the epidemiologic literature's inference that the sharp decline in cirrhosis mortality observed in Paris during the Second World War derived from a sharp constriction in wine consumption. Paris's wartime circumstances deviate substantially from the "all else being equal" assumption, and at least three other hypotheses for the cirrhosis decline may be contemplated. Historical and statistical review. Wartime Paris underwent tumultuous changes. Wine consumption did decline, but there were, as well, a myriad of other changes in diet and life experience, many involving new or heightened hardships, nutritional, experiential, institutional, health and mortality risks. Three competing hypotheses are presented: (1) A fraction of the candidates for cirrhosis mortality may have fallen to more sudden forms of death; (2) alcoholics, heavy drinkers and Paris's clochard subpopulation may have been differentially likely to become removed from the city's wartime population, whether by self-initiated departure, arrest and deportation, or death from other causes, even murder; and (3) there was mismeasurement in the cirrhosis mortality decline. The alcohol-cirrhosis connection provided the template for the alcohol research effort (now more than 20 years old) aimed at re-establishing scientific recognition of alcohol's direct alcohol-problems-generating associations and causal responsibilities. In a time given to reports of weaker associations of the alcohol-cirrhosis connection, the place and importance of the Paris curve in the wider literature, as regards that connection, remains. For this reason, the Paris findings should be subjected to as much research scrutiny as they undoubtedly deserve.

Stable two- and three-dimensional geometrically constrained magnetic structures: The action of magnetic fields

We show that equilibrium geometrically constrained domain patterns are two- or three-dimensional magnetic configurations localized around sharp constrictions. Their typical size w depends on both the length d and cross size a of the constriction. When $dl{L}_{0}$ the value $w\ensuremath{\simeq}\mathrm{min}[{(2a+d),L}_{0}],$ where ${L}_{0}$ is the conventional wall width. The localized structures undergo small deformation under magnetic fields and at a threshold field they detach from the constriction and magnetization reversal occurs.

The subfamilial and tribal classification of the family Asclepiadaceae

Abstract A modified classification of the family Asclepiadaceae R. Br. s.s . into three tribes — Secamoneae, Asclepiadeae s.l . and Stapelieae s.l . — is proposed. The position of attachment of the caudicles to the pollinia is suggested as a criterion for defining the erect and pendulous stature of the pollinaria. The concept of the transverse stature of pollinaria has been abandoned. In addition to the stature of the pollinaria, the morphology of the anther sacs (whether or not embedded in the tissue of the anther wings) and the position of anther wings with respect to the anther sacs are suggested as supplementary characters for tribal classification of the family. The characters of the gynoecium, particularly the presence or absence of true styles and the sharp constriction between stigma-head and ovaries (i.e. clavuncular morphology) have also been suggested as useful in differentiating Asclepiadeae s.l . and Stapelieae s.l ., along with the stature of the pollinaria. The circumscription of Asclepiadeae is emended to accommodate taxa of the former tribe Gonolobeae as a subtribe. The circumscription of Stapelieae has been retained in a wider sense, as suggested by Decaisne (1844). The tribes Fockeeae Kunze, Liede & Meve (1994), Marsdenieae Benth. (1876), Ceropegieae Benth. (1876), and Stapelieae s.s . sensu Benth. (1876; non Decne., 1844) have been relegated to subtribe status in the tribe Stapelieae Decne. (1844). Homology of the different parts of the gynoecium in the Asclepiadeae ( s.l .) with those in the Stapelieae ( s.l .) has been drawn. Segments of the style have been distinguished into ‘true style’ and ‘pseudostyle’, the former as parts of the ovary segment in development, the latter as stigma segment in development. The genus Tylophora R. Br. which was formerly treated under Stapelieae Decne. has been transferred to Asclepiadeae based on the morphology of the pollinaria, gynoecium and seed coat architecture.

Morphological patterns in the developing vertebrate retina

Changes in the morphology of the early optic cup were observed in embryos of two distantly-related vertebrate species, a teleost fish, northern pike (Esox lucius), and chicken (Gallus gallus). A similar morphological pattern was noted to appear in both species shortly after the involution of the optic vesicle and the formation of the inner retinal layer. At a gross level, three notches were observed in the retinal margin at approximately nasal, dorsal, and temporal positions, while in histological sections a sharp constriction was found in the thickness of the dorsal retinal layer. In both species, this dorsal constriction appeared to be continuous with the central or dorsal notch. The time of appearance and configuration of this morphological pattern is intriguingly similar to the specification and polarity of retinal positional markers, and suggest a segmentation hypothesis for the origin of retinal polarity.

Spatial evolution of the electron-energy distribution in the vicinity of a discharge-tube constriction.

We report experimental and calculational results of the spatial evolution of the electron-energy distribution function (EEDF) mean electron energy \ifmmode \bar{u}\else \={u}\fi{}, electric field E, and plasma density ${N}_{e}$, in the vicinity of a sharp constriction in a low-pressure mercury--rare-gas discharge. We explain many of the features of the EEDF by noting the absence of equilibrium between the electrons and the electric field. Our one-dimensional model of the spatial evolution of the EEDF is in good agreement with experimental results.

The biomechanical principles of upper urinary tract pressure-flow studies.

An experimental model is described in which the relationship between relative renal intrapelvic pressure and perfusion rate at varying degrees of ureteric obstruction was investigated in the rabbit ureter. There was smooth, laminar (Poiseuille) flow in the ureter over a wide range of flow rates even in the presence of sharp constrictions. The theoretical basis of these findings in terms of the fluid mechanics of collapsible tubes is defined and their importance in the assessment of equivocal upper tract obstruction discussed.

Tidally-induced residual currents in Long Island and Block Island Sounds

The tidally-induced residual currents in the Long Island Sound-Block Island Sound (LIS-BIS) tidal channel are investigated using a previously-developed analytic model. Known first order tidal properties of LIS-BIS are matched using three different models, chosen to isolate the effects of the factors potentially controlling the second order currents, either breadth, depth or eddy viscosity variations. The residual currents driven by these first order models agree to within roughly a factor of two, indicating that the model is not overly sensitive to these parameters. Tidally-induced currents on the order of observed currents in eastern LIS and BIS are predicted. The outstanding structural feature of the predicted residual currents is a region of strong surface flow divergence and bottom flow convergence centered at a sharp constriction in the channel. Eulerian and Lagrangian observations in eastern LIS and BIS are reviewed; indirect support for the theoretical results is found.

Spigelian hernias: anatomy and roentgenographic manifestations.

The anatomy of an uncommon but important type of lateral ventral hernia is reviewed. The key radiographic findings are air or contrast filled bowel seen laterally outside the confines of the peritoneal cavity, the “beak sign” of hernia, the sharp constriction of the proximal herniated loop, and the intermittent nature of the hernia. The setting in which to consider this diagnosis—acute bowel obstruction, intermittent abdominal pain, and “vanishing masses”—is discussed. The alert radiologist can suggest this diagnosis in cases in which the lesion is not found or appreciated by the clinician.

Desenvolvimento dos frutos nas espécies selvagens de amendoim (Arachis spp.)

As espécies selvagens de amendoim apresentam frutos completamente diferentes dos frutos do amendoim cultivado (Arachis hypogaea L.). Nesta espécie os frutos têm duas a cinco sementes justapostas dentro de uma única loja; externamente são observadas constrições na casca do fruto as quais em alguns casos se acentuam não chegando, entretanto, a produzir unia separação entre as sementes. Nas espécies selvagens os frutos apresentam duas sementes apenas, completamente separadas uma da outra por uma constrição muito profunda ou mesmo por um istmo de comprimento variável. Para êsses frutos foi adotada a denominação de "frutos catenados" e o estudo de seu desenvolvimento foi feito nas espécies Arachis monticola Krapovickas et Rigoni e A. villosa Benth. var. correntina Burk. O ovário, unilocular, tem normalmente dois óvulos. A futura separação das duas sementes se origina num tecido intercalar que se forma em ovários ainda jovens e que separa em duas a cavidade inicial única. Êste tecido tem a estrutura de um "peg" e, como êle, desidrata-se durante o processo de amadurecimento do fruto, tomando-se sêco e quebradiço; por essa razão, ao colhêr os frutos, a maioria dêles se apresenta unisseminado. Em 50% dos casos os óvulos se desenvolvem igualmente, conduzindo à formação de frutos com duas sementes. Quando os dois óvulos não se desenvolvem ao mesmo tempo, é mais freqüente o colapso do óvulo apical, cujo crescimento é paralisado cm diversos estados de desenvolvimento; isto conduz à formação de frutos com apenas uma semente ou com uma semente abortada. Além dessas duas, as seguintes espécies apresentam frutos catenados: Arachis Diogoi Hoehne f. typica Hoehne, A. glabrata Benth., A. pusilla Benth., A. marginata Gardn. (segundo Burkart), A. prostrata Benth. (segundo Burkart), e mais três espécies ainda não identificadas, mas que constam da coleção da Seção de Citologia como V. 44, V. 82 e V. 85. A V. 44 deve sera espécie A. villosulicarpa Hohene (segundo Krapovickas) (¹) e a V. 85 é, provávelmente o A. Diogoi Hoehne subspétie major Hoehne. A ocorrência de dois óvulos por ovário e de frutos catenados em tôdas as espécies selvagens que foram examinadas torna possível concluir que o mesmo processo descrito para Arachis monticola e A. villosa var. correntina explica a formação dos frutos catenados nas espécies selvagens que os possuem.

COARCTATION OF AORTA—ULCERATIVE AORTITIS—PERFORATION OF AORTA AND ACUTE PERICARDITIS

Coarctation, or stenosis of the aorta in the region of the ductus arteriosus, has been divided into two types. The infantile type consists of a narrowing of the aorta between the origin of the left subclavian artery and the site of the ductus arteriosus. It is an exaggeration or persistence of the anatomic condition found in the fetus. The adult type has no counterpart in normal intra-uterine life. It consists of a sharp constriction, at times complete obliteration, of the aorta, adjacent to the insertion of the ductus arteriosus. In this type, the symptoms of the condition may go unnoticed until some inter-current infection weakens the myocardium, or until some exertion increases the hypertension in the dilated vascular tree in the upper part of the body beyond the vascular reserve. Persons with such a condition may not complain of symptoms until the ages from 20 to 40. The condition has