Prevalence of Mannheimia haemolytica and Pasteurella multocida in goats from selected farms in Selangor, Malaysia

Mannheimia haemolytica and Pasteurella multocida are natural inhabitants of the upper respiratory tract of healthy animals and can cause pneumonic pasteurellosis in stressed animals. Healthy animals are able to control the multiplication of these bacteria and the inhaled bacteria, if they migrate to the lungs, will be cleared by the host defense mechanisms. Stress and other infections will cause the breakdown of the host defense mechanisms. These will lead to multiplication of the bacteria and colonisation of the lungs. Outbreaks of pneumonia occur in 10 to 14 days post-stress exposure. These bacteria are gram-negative, facultative anaerobes and have rod-shaped morphology. The special characteristic of these bacteria is that they show bipolar staining characteristic under Giemsa and Wright’s stains. Mannheimia haemolytica is haemolytic on blood agar and O-nitrophenyl-β, D-galactopyranoside (ONPG) positive while Pasteurella multocida is non-haemolytic on blood agar and ONPG negative. Ninety six (96) nasopharyngeal swab samples were taken from 4 goat farms in Selangor, Malaysia and bacterial isolation and identification were carried out. Presumptive isolates were identified by biochemical tests. Out of the 96 samples, 3 were positive for Mannheimia haemolytica and 11 positive for Pasteurella multocida. This gives a 3.13% and 11.46% prevalence rate for Mannheimia haemolytica and Pasteurella mutocida, respectively. The antibiotic sensitivity tests done on both isolates showed 29% were resistant to streptomycin and 21% resistant to compound sulfonamide. All isolates were sensitive to ampicillin and amoxicillin-clavulanic acid whilst 93% was sensitive to oxytetracycline and enrofloxacin. Even with low prevalence of Mannheimia haemolytica and Pasteurella multocida, it is important to control and prevent their infections and also to prevent further development of antimicrobial resistance as the disease is associated with these bacteria and have high economic impact

Mechanical Stress and Antioxidant Protection in the Retina of Hindlimb Suspended Rats

It has been postulated that hindlimb suspension (HS) causes a cephalad fluid shift in quadrupeds similar to that occurring to humans in microgravity. Therefore, HS may provide a suitable animal model in which to recapitulate the ocular changes observed in the human Visual Impairment and Intracranial Pressure (VIIP) syndrome. This work reports preliminary results from a tissue sharing project using 34 week-old Brown Norway rats. Two different experiments compared normal posture controls and HS rats for 2 weeks and rats exposed to HS for 2 weeks but allowed to recover in normal posture for 2 additional weeks. The effects of two nutritional countermeasures, green tea extract (GT) and plant polyphenol resveratrol (Rv), were also evaluated. Green tea contains the antioxidant epigallocatechin gallate (EGCG). qPCR gene expression analysis of selected targets was performed on RNA from isolated retinas, and histologic analysis was done on one fixed eye per rat. The transcription factor early growth response protein 1 (Egr1) was upregulated almost 2-fold in HS retinas relative to controls (P = 0.059), and its expression returned to control levels after 2 weeks of recovery in normal posture (P = 0.023). HS-induced upregulation of Egr1 was attenuated (but not significantly) in retinas from rats fed an antioxidant rich (GT extract) diet. In rats fed the GT-enriched diet, antioxidant enzymes were induced, evidenced by the upregulation of the gene heme oxygenase 1 (Hmox1) (P = 0.042) and the gene superoxide dismutase 2 (Sod2) (P = 0.0001). Egr1 is a stretch-activated transcription factor, and the Egr1 mechanosensitive response to HS may have been caused by a change in the translaminal pressure and/or mechanical deformation of the eye globe. The observed histologic measurements of the various retinal layers in the HS rats were lower in value than those of the control animal (n = 1), however insufficient data were available for statistical analysis. Aquaporin 4, a water-selective channel involved in interstitial fluid homeostasis, showed an upregulated trend in HS retinas; however, these results are preliminary. Total retinal thickness increased significantly (P = 0.049) in HS rats fed a resveratrol enriched diet compared to HS rats on a normal diet. This change appeared to be reversed during the 2 weeks of recovery post HS, but no differences in retina thickness were observed between HS animals and HS recovered animals when both groups consumed a normal diet. The reversibility of the increase in retinal thickness induced by resveratrol during HS may therefore reflect an interaction between the stress provoked by HS and the cytoprotective mechanisms elicited by resveratro

Highly efficient broadband conversion of light polarization by composite retarders

Driving on an analogy with the technique of composite pulses in quantum physics, we propose highly efficient broadband polarization converters composed of sequences of ordinary retarders rotated at specific angles with respect to their fast-polarization axes.Comment: 5 pages, 3 figures; check JOSA A 201

A Comparison of Course Quality Surveiy Results from Students on Gender Balanced and Gender Imbalanced Field Courses at NOLS

There is an extensive database of literature about diversity in outdoor Environmental Education and any of the studies focus on NOLS specifically. Several studies have investigated the impact of course composition in terms of gender as well as socioeconomic diversity; however, the research studies about course composition and gender were limited to differences between single gender and coed groups. The role of gender ratios on coed groups has not been widely researched. This study was designed to fill this gap in the research literature. Using course quality survey data, results showed that the student responses were significantly different between gender balanced and imbalanced courses. Students on gender-balanced courses responded more positively to questions about social interactions, their sense inclusion and group effectiveness. This is only a preliminary study however, and is unable to answer questions about why these differences exist. Outcomes from this study do raise additional questions about the nuanced social dynamics on NOLS field courses. Based on these results, I compiled a series of suggestions for NOLS, including future research questions

Time-Course of Changes in the Myonuclear Domain During Denervation in Young-Adult and Old Rat Gastrocnemius Muscle

If myonuclear loss initiates muscle wasting, it should precede the loss of muscle mass. As aging affects muscle plasticity, the time-course of muscle atrophy during disuse may differ between young and old animals. To investigate this, gastrocnemius muscles of 5- and 25-month-old rats were exposed to 1, 2, or 4 weeks of denervation, whereas the contralateral gastrocnemius muscles served as controls. Muscle fibers of each type responded similarly to 4 weeks of denervation. For both ages most of the atrophy (36%; P < 0.001) occurred in the first 2 weeks. In young-adult muscles, the myonuclear number remained constant, but in old muscles it decreased to below control level after 4 weeks of denervation (P < 0.05). Despite this differential response, myonuclear domain size decreased similarly at both ages (P < 0.001). In both young-adult and old rats, denervation-induced atrophy was not preceded by a loss of myonuclei. © 2011 Wiley Periodicals, Inc

Structure-Property Relationship of Nanomodified Mesophase Pitch-Based Carbon Fibers

Mesophase pitch-based carbon fibers are known for their excellent thermal and electrical conductivity, high tensile modulus, moderate tensile strength, but poor compressive strength. This collection of properties results from the texture and crystalline structure (together known as microstructure) of the fibers. Fiber microstructure, in turn, develops during processing due to the discotic nature of the mesophase pitch precursor. In prior studies, such important parameters as the size and shape of capillaries in the spinneret, spinning temperature and carbonization temperature have been varied to produce fibers with different microstructures and properties. In this dissertation, the primary research goal was to investigate how the microstructure and resulting transport properties of carbon fibers would be influenced by the incorporation of short aspect ratio multiwalled carbon nanotubes (MWCNTs) or, as a low-cost alternative, carbon black (CB) at ultra-dilute concentrations. Thus, MWCNTs and CB were dispersed into the mesophase pitch precursor at only 0.3 wt%. At this extremely low concentration, rather than acting as traditional fillers, these nanomodifiers served as surface-anchoring agents, which led to changes in the microstructure of the precursor and resulting carbon fibers. These microstructural modifications then impacted fiber and composite properties. In the first part of this study, the effect of nanomodification on fiber microstructure was evaluated. Using light and scanning electron microscopy, it was observed that the cross-section of unmodified (0 wt%) fibers had a well-defined radial texture, with minimal folding of the graphitic layers (average pleat length ~40 nm), especially for the large fraction (~83%) of fibers that exhibited “pac-man” type splitting. The cross-section of fibers modified with CB had a line-centered texture that exhibited increased folding of the graphitic planes (average pleat length ~30 nm) toward the outer surface of the fiber, resulting in ~45% of CB-modified fibers displaying “pac-man” splitting. Fibers modified with MWCNTs were found to have a largely random cross-sectional texture with significant folding of the graphitic planes (average pleat length ~30 nm) across the entire surface, and only ~3% of MWCNT-modified fibers showed “pac-man” splitting. Finally, via x-ray diffraction, it was determined that nanomodification had no adverse impact on crystallite size (Lc ~40 nm and La ~80 nm), orientation (FWHM ~2°), or graphitic perfection (d002 ~0.338 nm). This indicates that nanomodification could be a possible route for producing highly graphitic fibers, which are mechanically toughened by increased folding of the graphitic pleats. The second major component of this work focused on quantifying the density, electrical resistivity, thermal conductivity and mechanical properties of individual carbon fibers (i.e., single filaments). Using a set of calibrated cesium formate aqueous solutions, fiber densities were accurately measured to be 2.20 ≤ ρ0wt% \u3c 2.25 g/cm3, 2.15 ≤ ρMWCNT≤ 2.20 g/cm3, ρCB = 2.20 g/cm3. Thus, it was determined that external incorporation of nanomodifiers led to a small increase in percent void volume (~2%). This is consistent with a majority of literature studies that repeatedly show the undesired introduction of such voids with the incorporation of nanomodifiers. The single-filament electrical resistivity of the MWCNT-modified fibers (2.75±0.13 μΩ∙m) was not found to be significantly different (at a 95% confidence level) from the 0 wt% control (2.52±0.11 μΩ∙m); the CB-modified fibers only showed a slight increase in electrical resistivity (2.75±0.10 μΩ∙m). Similarly, fiber thermal conductivity (~550 W/m∙K) predicted from electrical resistivity values using the Issi-Lavin correlation showed no notable reduction as a result of nanomodification. Both nanomodified fibers showed a decrease in tensile strength (0 wt%: 1.71±0.21 GPa, MWCNT: 1.12±0.11 GPa and CB: 1.23±0.14 GPa) and modulus (0 wt%: 583±26 GPa, MWCNT: 520±26 GPa and CB: 527±30 GPa). Additionally, although a precise compressive strength for MWCNT- and CB-modified fibers could not be obtained (a result of limitations of the current tensile recoil testing method), all experimental fibers were determined to have a compressive strength of at least ~1 GPa. This is an improvement over previous studies. More notably, the difference in fiber structure achieved through nanomodification resulted in fibers with a better balance of compressive-to-tensile strength (σC/σT → 1), which is not observed for most highly conductivity conventional pitch-based carbon fibers. Another novel result from the present study is that the low-cost CB modifier was able to achieve similar changes in microstructure and properties as MWCNTs. In the final phase of this study, using both experimentation and finite element modeling, a method was developed to measure the bulk thermal conductivity of carbon fibers and their unidirectional composites. When applied to experimental fibers, no statistically significant difference in thermal conductivity was observed between MWCNT-modified (468±127 W/m∙K) and 0 wt% (514±179 W/m∙K) fibers. Additionally, these thermal properties were consistent with those predicted from single-filament electrical resistivity values (0 wt%: 569±18 W/m∙K, MWCNT: 533±20 W/m∙K). Thus, these types of composites could be useful as thermal management materials

Box Covers and Domain Orderings for Beyond Worst-Case Join Processing

Recent beyond worst-case optimal join algorithms Minesweeper and its generalization Tetris have brought the theory of indexing and join processing together by developing a geometric framework for joins. These algorithms take as input an index $\mathcal{B}$, referred to as a box cover, that stores output gaps that can be inferred from traditional indexes, such as B+ trees or tries, on the input relations. The performances of these algorithms highly depend on the certificate of $\mathcal{B}$, which is the smallest subset of gaps in $\mathcal{B}$ whose union covers all of the gaps in the output space of a query $Q$. We study how to generate box covers that contain small size certificates to guarantee efficient runtimes for these algorithms. First, given a query $Q$ over a set of relations of size $N$ and a fixed set of domain orderings for the attributes, we give a $\tilde{O}(N)$-time algorithm called GAMB which generates a box cover for $Q$ that is guaranteed to contain the smallest size certificate across any box cover for $Q$. Second, we show that finding a domain ordering to minimize the box cover size and certificate is NP-hard through a reduction from the 2 consecutive block minimization problem on boolean matrices. Our third contribution is a $\tilde{O}(N)$-time approximation algorithm called ADORA to compute domain orderings, under which one can compute a box cover of size $\tilde{O}(K^r)$, where $K$ is the minimum box cover for $Q$ under any domain ordering and $r$ is the maximum arity of any relation. This guarantees certificates of size $\tilde{O}(K^r)$. We combine ADORA and GAMB with Tetris to form a new algorithm we call TetrisReordered, which provides several new beyond worst-case bounds. On infinite families of queries, TetrisReordered's runtimes are unboundedly better than the bounds stated in prior work