Generation and breakdown of aerodynamic lift: Physical mechanism

A contribution is given to an old problem: the explanation of the generation of aerodynamic lift. Physical models are described which provide a better understanding of the phenomena involved

The Effect of Artificial Sweeteners in Chewing Gum, Helpful or Harmful?

Objective/Aims: This review of literature was designed to analyze the effects of artificial sweeteners in chewing gum in the oral cavity. The intent was to recognize which formulations of artificial sweeteners in chewing gum lead to beneficial outcomes in the oral cavity and which formulations lead to harmful effects. Methods: The review of literature analyzed the conclusions of primary and secondary resources accumulated from PubMed. Multiple scholarly studies were filtered based upon meta-analysis, cross-sectional, and cohort studies. The following key terms were used: artificial sweetener, chewing gum, plaque, saliva, microbes, and oral health. A summative report was created based upon the relevant findings. Articles selected were published after 2014. Results: The studies collected were assessed using a measure of saliva and plaque pH, salivary function, caries occurrence, remineralization, and oral flora. Xylitol made the most beneficial impact on the oral cavity. Research indicates artificial sweeteners have shown an immense advantage over conventional sugar in chewing gum, and its resulting effects on hard tissue. Conclusion: The relationship between artificial sweeteners and oral health supports different advantageous outcomes in the oral cavity. In conclusion, although studies using artificial sweeteners can show benefits to the oral cavity, the dose of artificial sweetener required to yield these results are often not found in chewing gum.https://scholarscompass.vcu.edu/denh_student/1012/thumbnail.jp

Effect of Transition to the Dry Period on Fecal Shedding of Coliform Bacteria in Dairy Cows

On well-managed dairy farms, environmental mastitis leading to clinical mastitis (CM) in dairy cows is common, and the most likely cause identified is certain gram-negative bacteria. Clinical mastitis is a very costly disease for farmers, limiting milk production and saleable milk, as well as negatively affecting milk quality. Previous studies have shown that the dry period is a critical time in the development of new intramammary infections that persist into the next lactation. In some beef feedlot studies, large increases in grain have resulted in increased fecal shedding of E. coli bacteria. Cows are fed primarily a high grain diet and a forage-based diet in lactation and the dry period, respectively. Lactating cows are fed high levels of grain to support high milk yields. The high level of grain in late lactation may be associated with higher fecal shedding of bacteria compared to the dry period when lower levels of grain are fed. The objective of this study was to quantify the effect of a rapid change in grain levels in the diet by measuring fecal shedding in dairy cows before and after dry-off. Fecal samples, from cows at two dairy farms either one week before drying off (n = 25) or two weeks into the dry period (n = 30), were taken rectally and immediately plated on MacConkey agar plates, selecting for coliform bacteria. The numbers of coliform bacteria in the feces of cows were measured to quantify the shift in bacterial shedding counts as affected by the transition between lactation and dry-off. Results showed no change in coliform levels between late-lactation and the dry period (P = 0.78). Because high variability of coliform fecal shedding was seen between cows on each farm, detection of changes associated with grain feeding were likely masked; however, additional studies following cows through the transition from lactation to dry-off are needed to confirm.OARDC SEEDS GrantCFAES Honors Research GrantNo embargoAcademic Major: Animal Science

Der Heilige Ibis (Threskiornis aethiopicus) in Beverungen

Ein exotischer Gast versetzte im August 2011 die Beverunger Bevölkerung in Aufruhr. Zwischen den Enten am Weserkai stelzte plötzlich ein Ibis umher. Zunächst stand man beim NABU Holzminden und bei der Landschaftsstation im Kreis Höxter den Meldungen über die Sichtung des Schreitvogels skeptisch gegenüber. Denn Verwechslungen bei gemeldeten Raritäten aus der Vogelwelt sind nicht selten. Doch ein Ortstermin beseitigte schnell jeden Zweifel: Es war ein Heiliger Ibis (Threskiornis aethiopicus), dessen eigentliche Heimat sich über das südlich der Sahara befindliche Afrika erstreckt. Der Koloniebrüter ist als Neozoon in Frankreich, Spanien und Italien verbreitet, ferner gibt es einzelne kleinere Populationen in Nordamerika. Einzug erhielt der zu der Familie der Ibisse und Löffler zählende Vogel in diese Gebiete, wenn auch ungewollt, durch die Hilfe des Menschen. Durch sein elegantes Erscheinungsbild und seine Zutraulichkeit, aber auch bedingt durch den Mythos, den diese Spezies schon zur Zeit der Pharaonen umgab, war der Ibis ein willkommener Gast in zoologischen Gärten, in denen er in freifliegenden Kolonien gehalten wurde. Einigen Exemplaren gelang die Flucht, deren Nachfahren heute, zum Teil mit drastischen Folgen für andere Vogelarten, in freilebenden Populationen sowohl an den Küsten aber auch im urbanen Raum anzutreffen sind. Die Gefahr, die vom Ibis für andere Vogelarten ausgeht, besteht nicht darin, dass er den Lebensraum der einheimischen Arten besetzt, sondern darin, dass auf dem Speiseplan des Nahrungsopportunisten neben Wirbellosen, Amphibien und kleinen Fischen auch die Eier und Jungtiere anderer Seevögel stehen [YÉSOU & CLERGEAU 2005]. Bei dem Beverunger Ibis handelte es sich ebenfalls um einen Gefangenschaftsflüchtling. Ein deutliches Anzeichen dafür war der weiße Ring an seinem rechten Bein, aber auch seine Zutraulichkeit gegenüber dem durch ihn verursachten Zustrom neugieriger Besucher. Diese konnten den Ibis nicht nur aus nächster Nähe fotografieren sondern auch aus der Hand füttern

Effects of butyrate− on ruminal Ca2+ transport: evidence for the involvement of apically expressed TRPV3 and TRPV4 channels

The ruminal epithelium absorbs large quantities of NH4+ and Ca2+. A role for TRPV3 has emerged, but data on TRPV4 are lacking. Furthermore, short-chain fatty acids (SCFA) stimulate ruminal Ca2+ and NH4+ uptake in vivo and in vitro, but the pathway is unclear. Sequencing of the bovine homologue (bTRPV4) revealed 96.79% homology to human TRPV4. Two commercial antibodies were tested using HEK-293 cells overexpressing bTRPV4, which in ruminal protein detected a weak band at the expected ~ 100 kDa and several bands ≤ 60 kDa. Immunofluorescence imaging revealed staining of the apical membrane of the stratum granulosum for bTRPV3 and bTRPV4, with cytosolic staining in other layers of the ruminal epithelium. A similar expression pattern was observed in a multilayered ruminal cell culture which developed resistances of > 700 Ω · cm2 with expression of zonula occludens-1 and claudin-4. In Ussing chambers, 2-APB and the TRPV4 agonist GSK1016790A stimulated the short-circuit current across native bovine ruminal epithelia. In whole-cell patch-clamp recordings on HEK-293 cells, bTRPV4 was shown to be permeable to NH4+, K+, and Na+ and highly sensitive to GSK1016790A, while effects of butyrate− were insignificant. Conversely, bTRPV3 was strongly stimulated by 2-APB and by butyrate− (pH 6.4 > pH 7.4), but not by GSK1016790A. Fluorescence calcium imaging experiments suggest that butyrate− stimulates both bTRPV3 and bTRPV4. While expression of bTRPV4 appears to be weaker, both channels are candidates for the ruminal transport of NH4+ and Ca2+. Stimulation by SCFA may involve cytosolic acidification (bTRPV3) and cell swelling (bTRPV4)

The TRPV3 channel of the bovine rumen: localization and functional characterization of a protein relevant for ruminal ammonia transport

Large quantities of ammonia (NH3 or NH4+) are absorbed from the gut, associated with encephalitis in hepatic disease, poor protein efficiency in livestock, and emissions of nitrogenous climate gasses. Identifying the transport mechanisms appears urgent. Recent functional and mRNA data suggest that absorption of ammonia from the forestomach of cattle may involve TRPV3 channels. The purpose of the present study was to sequence the bovine homologue of TRPV3 (bTRPV3), localize the protein in ruminal tissue, and confirm transport of NH4+. After sequencing, bTRPV3 was overexpressed in HEK-293 cells and Xenopus oocytes. An antibody was selected via epitope screening and used to detect the protein in immunoblots of overexpressing cells and bovine rumen, revealing a signal of the predicted ~ 90 kDa. In rumen only, an additional ~ 60 kDa band appeared, which may represent a previously described bTRPV3 splice variant of equal length. Immunohistochemistry revealed staining from the ruminal stratum basale to stratum granulosum. Measurements with pH-sensitive microelectrodes showed that NH4+ acidifies Xenopus oocytes, with overexpression of bTRPV3 enhancing permeability to NH4+. Single-channel measurements revealed that Xenopus oocytes endogenously expressed small cation channels in addition to fourfold-larger channels only observed after expression of bTRPV3. Both endogenous and bTRPV3 channels conducted NH4+, Na+, and K+. We conclude that bTRPV3 is expressed by the ruminal epithelium on the protein level. In conjunction with data from previous studies, a role in the transport of Na+, Ca2+, and NH4+ emerges. Consequences for calcium homeostasis, ruminal pH, and nitrogen efficiency in cattle are discussed

Pattern recognition of star constellations for spacecraft applications

A software system for a star imager for “on-line ” satellite attitude determination is described. The system works with a single standard commercial CCD-camera with a high aperture lens and an on-board star catalogue. It is capable of both an initial coarse attitude determination without any a priori knowledge of the satellite orientation and a high accuracy attitude determination based on prediction and averaging of several identified star constellations. In the high accuracy mode the star imager aims at an accuracy better than 2 arc sec. with a processing time of less than a few seconds. The star imager is developed for the Danish “micro satellite ” Oersted