16,648 research outputs found
Prevention of ulcer disease in goldfish by means of vaccination
A vaccine comprising cells of Aeromonas bestiarum grown in tryptic soy broth and atypical A. salmonicida cells produced in iron-limited and iron-supplemented media protected goldfish Carassius auratus when administered by immersion (dosage ≈ 5 × 107 cells/mL for 60 s) followed after 28 d by an oral booster (dosage = 5 × 107 cells/g of feed), which was fed for 7 d so that each fish received about 1 g of vaccine-containing feed. After challenge by intramuscular injection of a virulent culture of atypical A. salmonicida, the relative percent survival (RPS) was more than 90%. The approach was more successful than using a commercial furunculosis vaccine with or without supplementation with A. bestiarum or atypical A. salmonicida cells. Moreover, a smooth derivative of the virulent rough culture of atypical A. salmonicida was less effective as a vaccine candidate, yielding an RPS of only 65%. Low antibody titers of 1:39–1:396 were found in the vaccinated fish. The vaccinated fish had a significantly higher proportion of dead head kidney macrophages (10.9 ± 3.5%; P = 0.0149) than did the controls (6.8 ± 3.1%). However, differences in the number of erythrocytes and leukocytes, the level of phagocytic and lysozyme activities, and the proportion of lymphocytes, monocytes, and polymorphonuclear cells were not statistically significant between the two groups
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Muscle function during takeoff and landing flight in the pigeon (Columba livia)
This study explored the muscle strain and activation patterns of several key flight muscles of the pigeon (Columba livia) during takeoff and landing flight. Using electromyography (EMG) to measure muscle activation, and sonomicrometry to quantify muscle strain, we evaluated the muscle function patterns of the pectoralis, biceps, humerotriceps and scapulotriceps as pigeons flew between two perches. These recordings were analyzed in the context of three-dimensional wing kinematics. To understand the different requirements of takeoff, midflight and landing, we compared the activity and strain of these muscles among the three flight modes. The pectoralis and biceps exhibited greater fascicle strain rates during takeoff than during midflight or landing. However, the triceps muscles did not exhibit notable differences in strain among flight modes. All observed strain, activation and kinematics were consistent with hypothesized muscle functions. The biceps contracted to stabilize and flex the elbow during the downstroke. The humerotriceps contracted to extend the elbow at the upstroke-downstroke transition, followed by scapulotriceps contraction to maintain elbow extension during the downstroke. The scapulotriceps also appeared to contribute to humeral elevation. Greater muscle activation intensity was observed during takeoff, compared with mid-flight and landing, in all muscles except the scapulotriceps. The timing patterns of muscle activation and length change differed among flight modes, yet demonstrated that pigeons do not change the basic mechanical actions of key flight muscles as they shift from flight activities that demand energy production, such as takeoff and midflight, to maneuvers that require absorption of energy, such as landing. Similarly, joint kinematics were consistent among flight modes. The stereotypy of these neuromuscular and joint kinematic patterns is consistent with previously observed stereotypy of wing kinematics relative to the pigeon's body (in the local body frame) across these flight behaviors. Taken together, these observations suggest that the control of takeoff and landing flight primarily involves modulation of overall body pitch to effect changes in stroke plane angle and resulting wing aerodynamics.Organismic and Evolutionary Biolog
Absorption of Energy at a Metallic Surface due to a Normal Electric Field
The effect of an oscillating electric field normal to a metallic surface may
be described by an effective potential. This induced potential is calculated
using semiclassical variants of the random phase approximation (RPA). Results
are obtained for both ballistic and diffusive electron motion, and for two and
three dimensional systems. The potential induced within the surface causes
absorption of energy. The results are applied to the absorption of radiation by
small metal spheres and discs. They improve upon an earlier treatment which
used the Thomas-Fermi approximation for the effective potential.Comment: 19 pages (Plain TeX), 2 figures, 1 table (Postscript
Combinations of isoform-targeted histone deacetylase inhibitors and bryostatin analogues display remarkable potency to activate latent HIV without global T-cell activation
AbstractCurrent antiretroviral therapy (ART) for HIV/AIDS slows disease progression by reducing viral loads and increasing CD4 counts. Yet ART is not curative due to the persistence of CD4+ T-cell proviral reservoirs that chronically resupply active virus. Elimination of these reservoirs through the administration of synergistic combinations of latency reversing agents (LRAs), such as histone deacetylase (HDAC) inhibitors and protein kinase C (PKC) modulators, provides a promising strategy to reduce if not eradicate the viral reservoir. Here, we demonstrate that largazole and its analogues are isoform-targeted histone deacetylase inhibitors and potent LRAs. Significantly, these isoform-targeted HDAC inhibitors synergize with PKC modulators, namely bryostatin-1 analogues (bryologs). Implementation of this unprecedented LRA combination induces HIV-1 reactivation to unparalleled levels and avoids global T-cell activation within resting CD4+ T-cells.</jats:p
Effect of Loading Wave Profile on Hydrodynamic Void Collapse in Detonation Initiation
We experimentally and numerically investigate void collapse as a mechanism for detonation initiation in porous energetic materials under a stress-wave loading condition, representative of accidental mechanical insult. In contrast to the step loading of a shock, a
stress wave induces a ramp loading, where length scales of the wave may be comparable to
the void size. Using an inert and transparent polymer material, we decouple the reactive
and material aspects of void collapse, and focus instead on the hydrodynamic process of
interactive void collapse. Diagnostic techniques include high speed shadowgraph movies
of the collapsing voids and particle image velocimetry in the surrounding material. Two
dimensional finite volume simulations compare the interaction of a single void undergoing
ramp and shock wave loading. Voids exhibit asymmetric collapse, with formation of a high
speed jet that originates from proximal wall of the void. Data obtained, including internal
volume histories and collapse times of current experiments and simulations, are reported
and compared with shock-induced cavity collapse data from the literature
Nudges and other moral technologies in the context of power: Assigning and accepting responsibility
Strawson argues that we should understand moral responsibility in terms of our practices of holding responsible and taking responsibility. The former covers what is commonly referred to as backward-looking responsibility , while the latter covers what is commonly referred to as forward-looking responsibility . We consider new technologies and interventions that facilitate assignment of responsibility. Assigning responsibility is best understood as the second- or third-personal analogue of taking responsibility. It establishes forward-looking responsibility. But unlike taking responsibility, it establishes forward-looking responsibility in someone else. When such assignments are accepted, they function in such a way that those to whom responsibility has been assigned face the same obligations and are susceptible to the same reactive attitudes as someone who takes responsibility. One family of interventions interests us in particular: nudges. We contend that many instances of nudging tacitly assign responsibility to nudgees for actions, values, and relationships that they might not otherwise have taken responsibility for. To the extent that nudgees tacitly accept such assignments, they become responsible for upholding norms that would otherwise have fallen under the purview of other actors. While this may be empowering in some cases, it can also function in such a way that it burdens people with more responsibility that they can (reasonably be expected to) manage
From “White Fathers” to “Black Fathers” in Kasama and Mpika Dioceses in Zambia
Employing the missiological theory of Henry Venn (1796-1873) and Rufus Anderson (1796-1880) on indigenisation of churches, this article explores the lived experiences of black Zambian Catholic clergymen, nuns, catechists and lay people at some of the mission stations that were once in the hands of Missionaries of Africa, popularly known as White Fathers, from 1891to1991 in the Archdiocese of Kasama and Diocese of Mpika. To write about the White Fathers from the point of view of our interviewees accords us an auspicious opportunity to pay tribute to Fr. Hugo Hinfelaar to whom this article and this particular issue of the Zambia Journal of Social Sciences is dedicated. Having arrived in Zambia as a young Dutch White Father missionary in 1958, Fr. Hinfelaar desired to understand the culture of the Bemba people among whom he was working. He, therefore, became a serious field worker – an anthropologist, historian and theologian. He retired and returned home in 2014, after having contributed to the efforts of indigenising the Catholic Church’s clergy and inculturation of the Catholic faith in the country. The article demonstrates that the indigenisation of Kasama and Mpika Dioceses was incomplete. This is because, of the “three selves”: self-propagating church, self-sustaining church and self-governing church in the indigenisation theory, the self-sustaining church has not been realised according to the respondents, although some of them spoke of the White Fathers having accomplished their mission. This article proposes a reengagement with the discourse of ‘self-sustainability’ which has largely been abandoned by local Catholic theologians. However, it is now an issue which has become all too apparent to be ignored as the Catholic Church becomes more and more indigenised, at least in terms of its clergy. This article proposes a new theme in Church history in Zambia, namely, the localisation of the personnel and self-sustainability in the Catholic Church in Zambia
Chocolate Bar Wrapping Machine
Gilbert Chocolates has proposed to manufacture a machine to wrap chocolate bars. This machine is intended to replace two people wrapping the chocolate bars by hand, which is a time consuming method. This is especially apparent between October and January when the workers are working long hours in preparation for the Christmas rush of customers. Currently wrapping a bar takes about a minute and Gilbert Chocolates wants this time reduced down to 20-30 seconds. The budget for this project is set at $1000, and is being funded by the company. This machine needs to fit in a cubic foot of space and weigh under 30 pounds for storage purposes. This device can be either purely mechanical with manual input, or it may use step motors and a controller. This project pulls from our knowledge in kinematics, dynamics, 3D modeling, tolerance analysis, material selection, manufacturing techniques, and design of components. From doing this project we will learn how to apply all of these concepts together to solve real world problems. This project will encompass the design, manufacturing of a prototype, and optimization of the chocolate bar wrapping machine in hopes that the price of manufacturing chocolate bars can be reduced for Gilbert Chocolates. The final presentation of this project will include a working prototype, a report, and a presentation. The project will be presented at the Engineering Senior Design Project day. The machine will be operated and displayed at this event
The silence of self-knowledge
Gareth Evans famously affirmed an explanatory connection between answering the question whether p and knowing whether one believes that p. This is commonly interpreted in terms of the idea that judging that p constitutes an adequate basis for the belief that one believes that p. This paper formulates and defends an alternative, more modest interpretation, which develops from the suggestion that one can know that one believes that p in judging that p
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