Inelastic collisions of positrons with one-valence-electron targets

The total elastic and positronium formation cross sections of the inelastic collisions between positrons and various one-valence-electron atoms, (namely hydrogen, lithium, sodium, potassium and rubidium), and one-valence-electron ions, (namely hydrogen-like, lithium-like and alkaline-earth positive ions) are determined using an elaborate modified coupled-static approximation. Special attention is devoted to the behavior of the Ps cross sections at the energy regions lying above the Ps formation thresholds

Anatomical traits of some species of Kalanchoe (Crassulaceae) and their taxonomic value

AbstractAnatomical studies of the stems and leaves of 15 species of the genus Kalanchoe were studied. Anatomical examination of the cross sections of the above mentioned stems and leaves revealed diagnostic characters among species. Data of comparative characters reached 42 couplet characters; data matrix was organized on the basis of variations to obtain a classification using sequential indented key. Data matrix included the anatomical description and features of the epidermis, cortex, pericycle, vascular bundles and pith for stem anatomy and epidermis, mesophyll, midrib region and vascular bundles for leaf anatomy

A patient-specific adaptation of the Living Human Heart Model in application to pulmonary hypertension

The Living Heart Project aims to offer medical practitioners and researchers a full-heart electromechanical computational platform to explore and assess clinical cases pertaining to the left ventricle (LV), and the less addressed right ventricle (RV). It does not, however, provide an easy solution to applying this platform to patient-specific cases that account for a large variability among cases. We, therefore, present a solution to modify the Living Human Heart Model (LHHM) to obtain a patient-specific geometry using the thermal expansion method, with iteratively adjusted parameters that accurately simulate the case of a 72-year-old female patient suffering from secondary pulmonary hypertension caused by mitral valve regurgitation (MR). The patient underwent MV replacement and we simulate the heart from magnetic resonance imaging (MRI) images prior to surgery and 3 days following surgery. A mean pulmonary arterial pressure (mPAP) of approximately 64 mmHg was demonstrated before surgery, along with a severe lack of coaptation of the mitral valve. Reduced function of the cardiac chambers is exhibited in the reduced ejection fraction (EF). We also demonstrate left-side failure, an increase in Global Longitudinal Strain (GLS) and the location of maximum cardiac wall stress located at the mid anterolateral wall of the RV where dilation traditionally manifests. Comparison of patient geometry pre-operation and post-surgery showed a change in shape of the Tricuspid Annulus (TA) in systole. A rigid constraint across the TA was used to simulate an annuloplasty ring, and an increase in ring-widening forces was observed post-operation, with a significant reduction in forces being present in contractile forces on the ring. This model led us to conclude that the patient will likely develop TV annular dilatation and subsequent regurgitation in the absence of intervention. We verify the use of the LHHM for assessing potential remodeling and subclinical RV dysfunction, and subsequent intervention and attenuation of pulmonary hypertension by a mitral valve replacement. The lack of personalization and wide variability have remained a significant reason for the slow adoption rate of computational tools among medical practitioners, but we see this work as a substantial addition to computational cardiology, and foresee a closer integration of such technology to mainstream application among members of the medical community

Temperature effects on the electrical performance of large area multicrystalline silicon solar cells using the current shunt measuring technique

The temperature effects on the electrical performance of a large area multicrystalline silicon solar cell with back-contact technology have been studied in a desert area under ambient conditions using the current shunt measuring technique. Therefore, most of the problems encountered with traditional measuring techniques are avoided. The temperature dependency of the current shunt from 5ºC up to 50ºC has been investigated. Its temperature coefficient proves to be negligible which means that the temperature dependency of the solar cell is completely independent of the current shunt. The solar module installed in a tilted position at the optimum angle of the location, has been tested in two different seasons (winter and summer). The obtained solar cell short circuit current, open circuit voltage and output power are correlated with the measured incident radiation in both seasons and all results are discussed

An improved design of a fully automated multiple output micropotentiometer

This paper describes in details a new design of a fully automated multiple output micropotentiometer (?pot). A prototype has been built at the National Institute for Standards (NIS), Egypt to establish this highly improved AC voltage source in the millivolt range. The new device offers three different outputs covering a wide frequency range from only one outlet. This valuably supports the precise sourcing ranges of low AC voltage at NIS. The design and the operation theory of this prototype have been discussed in details. An automatic calibration technique has been introduced through specially designed software using the LabVIEW program to enhance the calibration technique and to reduce the uncertainty contributions. Relative small AC-DC differences of our prototype in the three output ranges are fairly verified. The expanded uncertainties of the calibration results for the three output ranges have been faithfully estimated. However, further work is needed to achieve the optimum performance of this new device

REDEEMING THE BETRAYED BODY: Technology and Embodiment in the Fiction of Thomas Pynchon and Don DeLillo

This thesis presents a reading of the fiction of Don DeLillo and Thomas Pynchon that focuses on the significance of embodiment in the authors’ technologically mediated worlds. The study draws upon the work of Vivian Sobchack, Steven Connor, Merleau-Ponty, and Jean-Paul Sartre. Critics of DeLillo and Pynchon’s fiction have generally avoided phenomenological perspectives; as a result, the concept of corporeality has not been thoroughly examined. Thus, the thesis examines the fiction of Pynchon and DeLillo in light of theories of embodiment that have been overlooked. Central to the thesis is a study of the theoretical and technical aspects of visual and auditory technology that is focused on how the authors depict an intrinsic connection between the physical body and prosthetics. To subvert the conventional dichotomy between the human and the technological, the thesis explores the sensory experiences of the characters, drawing attention to the inextricable connection between the body and the world. The analysis also considers the significance of the unity of the senses and the connection this has to the manner in which the body’s materiality is depicted. Moreover, the concept of monstrosity is used to explore how the authors portray the fluidity and the multiplicity of the human body. Giving a close reading of the body’s inherent connection to technology and the prominence of materiality, the thesis suggests that the characters depict subjective experiences that are rooted in their physicality. Technology is not perceived, in its conventional sense, as a means of disembodying the characters; on the contrary, it is the gateway to exploring corporeality

Stereoelectronics of Carboxylate-Imidazolium Hydrogen Bonds in Models of the Aspartate-Histidine Couple in Serine Proteases.

The geometry of the carboxylate-imidazolium hydrogen bond in the crystalline state and the effect of microenvironment are investigated in models of the aspartate-histidine (Asp-His) couple. Synthetic methods leading to the preparation of intramolecular models, possessing syn and anti-oriented hydrogen bonds, also are described. A single-pot procedure has been developed for converting phenoxyacetonitriles into their respective benzimidazole derivative in higher yields than the traditional two step procedure. An efficient single-pot procedure also has been developed for converting benzofuran to its acetylene derivative, 2-acetoxyphenylacetylene. This method involves in situ acetylation of the unstable phenol intermediate. Nine intermolecular imidazolium-benzoate couples have been prepared and their structures analyzed by single crystal X-ray crystallography. The structure of an intramolecular model also has been determined by single crystal X-ray crystallography. The orientation of all the imidazolium hydrogen bonds is syn relative to the carboxylate. Furthermore, syn hydrogen bonds are shorter than anti hydrogen bonds. The strength of the hydrogen bond increases as $\Delta$pK\sb{\rm a} between the donor and acceptor decreases. The basicity of the carboxylate is governed by the number of hydrogen bonds accepted by it: successive hydrogen bonding to carboxylate decreases its basicity. Consequently, correlations of hydrogen-bond strength and basicity (pK\sb{a} and PA) of carboxylates are more reliable when carboxylates accept equal number of hydrogen bonds. Stereoelectronics of syn hydrogen bonding to carboxylates are affected by the presence of strong and geometrically constrained anti hydrogen bonding. With respect to the plane of the carboxylate, syn hydrogen bonding lies (1) within 10\sp\circ in the absence of anti hydrogen bonding, (2) out-of-plane (30-35\sp\circ) in the presence of one anti hydrogen bond, and (3) within 10\sp\circ in the presence of two anti hydrogen bonds. Out-of-plane distortion in the presence of an anti-oriented hydrogen bond suggests a catalytic role for the anti-oriented Ser-214 side-chain in serine proteases