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21.
Recent numerical simulations have yielded the most efficient geodynamo, having the largest dipole intensity when reversal frequency is low. Reliable paleointensity data are limited but heretofore have suggested that reversal frequency and paleointensity are decoupled. We report data from 56 Thellier-Thellier experiments on plagioclase crystals separated from basalts of the Rajmahal Traps (113 to 116 million years old) of India that formed during the Cretaceous Normal Polarity Superchron. These data suggest a time-averaged paleomagnetic dipole moment of 12.5 +/- 1.4 x 10(22) amperes per square meter, three times greater than mean Cenozoic and Early Cretaceous-Late Jurassic dipole moments when geomagnetic reversals were frequent. This result supports a correlation between intervals of low reversal frequency and high geomagnetic field strength. 相似文献
22.
Cottrell FG 《Science (New York, N.Y.)》1937,85(2214):529-533
23.
Equine grass sickness (EGS) is a pan-dysautonomia of horses that involves central and peripheral neuronal degeneration and ultimately depletion. This is the first reported functional study on the motility of equine intestine taken immediatelypost mortem from horses with EGS. Strips of smooth muscle from the small intestine of healthy and EGS-affected horses were suspended in an organ bath and their motility was measured isometrically. The activity of the cholinergic system was studied. Physostigmine enhanced the motility of all muscle strips. Tissues taken from horses suffering from acute grass sickness (AGS) had the longest latency before a measurable response could be obtained (p<0.05). The ileum appeared to be damaged by EGS to a greater extent than the duodenum. For the duodenal strips the enhanced rate of spontaneous contractions was significant (p<0.05) for both normal tissue and that affected by grass sickness but this was not the case for the ileal strips. Muscarinic receptor sensitivity investigation using bethanecol suggested a hypersensitivity of receptors with AGS material,Abbreviations AGS
acute grass sickness
- CGS
chronic grass sickness
- ED50
median effective dose
- EGS
equine grass sickness
- VIP
vasoactive intestinal peptide 相似文献
24.
Fan Liu Jeremy James Cottrell Cherie Louise Collins David James Henman Kirrily Sharon Beatrice O’Halloran Frank Rowland Dunshea 《Tropical animal health and production》2017,49(7):1461-1469
Heat stress (HS) exacerbates the body weight loss of lactating sows and reduces litter weight gain. Selenium (Se), vitamin E (VE), chromium (Cr) and betaine have been shown to ameliorate symptoms of HS, and yeast nucleotides and mannan oligosaccharides have been reported to improve lactational performance and immune response in pigs. Therefore, a combination of these nutrients may improve lactational performance of sows in summer. The effects of two nutritionally enhanced diets on lactational performance of sows in summer were investigated in two experiments. In experiment 1, we compared the effects of a nutritionally fortified diet (0.4 ppm Se, 95 IU/kg VE, 0.4 ppm Cr and 0.2% betaine; named as SVCB diet) with the NRC 2012 standard diet (0.15 ppm Se, 44 IU/kg VE) on lactational performance of sows in summer. Results showed that the SVCB diet reduced body weight loss (P = 0.039) and tended to reduce backfat loss (P = 0.075) of sows without affecting feed intake, while litter weight gain was not influenced. In experiment 2, we further enhanced the nutrients in the SVCB diet (0.8 ppm Se, 1% yeast nucleotides, and 0.1% mannan oligosaccharides; named as SNM diet). Results showed that the SNM diet did not improve feed intake of sows, farrowing performance, or litter weight gain compared with the SVCB diet, but increased body weight loss of the third parity sows (P = 0.037). Overall, a combined supplementation of Se, VE, Cr, and betaine above the NRC recommended levels can reduce mobilisation of body reserve of lactating sows in summer. 相似文献
25.
The forelimbs joints and bones of 16 normal goats and sheep were studied to determine optimal injection techniques for the shoulder, elbow, and carpal joints. Based on the findings, trial injections of marker substances were made in 8 anesthetized animals. The joints were then dissected and rates of success were determined, and they were 88% of shoulder, 87% of elbow, 94% of radiocarpal, and 81% of midcarpal and carpometacarpal joints. 相似文献
26.
Unitary impulse activity from tension receptors in the abomasal antrum in sheep anaesthetized with chloralose was studied with concurrent measurements of isometric tension in the antral wall, intraluminal pressures and electromyography (EMG). Rhythmical background activity had a close correlation with intraluminal pressure changes and usually a close correlation with local increases in EMG activity and isometric tension. Impulse frequencies increased, but were not sustained, following changes from isotonic to isometric conditions. Tension receptors were excited by transmural compression, by antral distension and by local intra-arterial injections of acetylcholine (2.5–25 µg), pentagastrin (10–20 µg), 5-hydroxytryptamine (1–20 µg), adrenaline (10 µg) cholecystokinin-8 (1–5 µg) or bradykinin (0.5–20 µg), and by systemic injections of bethanecol (5–1000 µg). Local intra-arterial perfusions of atropine (50 µg) and hexamethonium (100 µg) did not abolish spontaneous antral movements or affect the enhanced impulse activity evoked by acetylcholine or 5-hydroxytryptamine. Most antral tension receptors were excited by increases in antral tension or passive distension; they therefore functioned in series with the muscularis externa. The discharges of three tension receptors were off-loaded early during the contraction evoked by local injections of pentagastrin (10–20 µg).Abbreviations b-t
balloon-tipped
- EMG
electromyography
- IMP
impulse
- TTL
transistor-transistor logic
On study leave from University of Massey, Palmerston North, New Zealand 相似文献
27.
Prevalence and Spatial Distribution of Salmonella Infections in the Pennsylvania Raccoon (Procyon lotor)
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K. J. Very M. K. Kirchner N. Shariat W. Cottrell C. H. Sandt E. G. Dudley S. Kariyawasam B. M. Jayarao 《Zoonoses and public health》2016,63(3):223-233
A study was conducted to determine the prevalence and spatial distribution of Salmonella infection in Pennsylvania raccoons (Procyon lotor), common wildlife mammals known to occupy overlapping habitats with humans and domestic food animals. The Pennsylvania Game Commission provided a total of 371 raccoon intestinal samples from trapped and road‐killed raccoons collected between May and November 2011. Salmonella was isolated from the faeces of 56 (15.1%) of 371 raccoons in 35 (54%) of 65 counties across Pennsylvania. The five most frequently isolated serotypes were Newport (28.6%), Enteritidis (19.6%), Typhimurium (10.7%), Braenderup (8.9%) and Bareilly (7.1%). Pulsed‐field gel electrophoresis (PFGE) analysis of the Salmonella isolates and subsequent comparison to the Pennsylvania Department of Health human Salmonella PFGE database revealed 16 different pulsetypes in Salmonella isolates recovered from raccoons that were indistinguishable from pulsetypes of Salmonella collected from clinically ill humans during the study period. The pulsetypes of seven raccoon Salmonella isolates matched those of 56 human Salmonella isolates by month and geographical region of sample collection. Results from Clustered Regularly Interspaced Short Palindromic Repeats and Multi‐Virulence Locus Sequence Typing (CRISPR‐MVLST) analysis corroborated the PFGE and serotyping data. The findings of this study show that several PFGE pulsetypes of Salmonella were shared between humans and raccoons in Pennsylvania, indicating that raccoons and humans might share the same source of Salmonella. 相似文献
28.
Electrophysiological techniques were used to record afferent activity in the superior spermatic nerves of young lambs under general anaesthesia. Receptive fields were identified in the pampiniform plexus and the deep tissue of the testis in response to mechanical stimulation. Application of a standard rubber castration ring to the scrotal neck evoked vigorous afferent activity, including some from formerly silent units with receptive fields particularly in the pampiniform plexus. Some of this multi-unit discharge adapted rapidly within 10 s of the application of the ring and was followed by a discharge pattern which decayed exponentially over 90 min. The rate of decay of this discharge showed more than one exponent (time constant) with inflections at approximately 90 s and 16 min. After the application of the castration ring, quantitatively controlled scrotal compression continued to excite receptors, though a declining frequency was recorded over the period of observation. It was concluded that: (a) rubber castration rings initiated afferent activity which persisted for periods in excess of 90 min, a time course which is similar to the behavioural and humoral changes in the conscious animal; (b) both standard and small rubber castration rings were ineffective in rapidly producing neuronal pressure block of the slowly conducting afferent fibres in the superior spermatic nerve; (c) intra-testicular injection of local anaesthetic rapidly blocked afferent fibres running in the superior spermatic nerve.Abbreviations TTL
transistor transistor logic 相似文献
29.
Cottrell FG 《Science (New York, N.Y.)》1937,85(2215):553-556
30.