202 research outputs found
Individual variation in the antisnake behavior of California ground squirrels (Spermophilus beecheyi)
California ground squirrels (Spermophilus beecheyi) have evolved behavioral defenses against their two predators, the northern Pacific rattlesnake (Crotalus viridis oreganus) and Pacific gopher snake (Pituophis melanoleucus catenifer). Two studies were used to examine individual variation in antisnake behavior as it might be affected by selection operating on arousability, fearfulness, and aggressiveness. In Study 1 the behavioral consistency of two litters of lab-reared juveniles was examined at two age periods during encounters with a caged gopher snake and domestic cat. Close-range investigation and tail flagging appeared to be governed by short-term motivational states that were not strongly correlated across age. Age correlations revealed that individual tendencies to throw substrate were relatively consistent for the snake and even more so for the cat. In Study 2, wild-caught adults were obtained from five sites where rattlesnakes and gopher snakes were abundant and from five sites where these snakes were rare or absent. Squirrels in a seminatural laboratory setting were given balanced presentations of a caged rattlesnake and gopher snake separated by 5 days. Snakes were recognized by all squirrels as potentially dangerous, irrespective of experience, age, and selective regime. Substrate throwing also was positively correlated for the two snakes in both groups of adults, indicating that level of aggressiveness is a consistent component of temperament not specific to species of snakes. Physiological arousal was not correlated strongly for the two snakes, but it was significantly lower in squirrels from sites where snakes were abundant. This suggests some specialization to reduce anxiety that possibly enhances tactical decision making
Effects of Herbivore-Induced Vegetation Change on Interactions Between Rodents and Songbirds in Shortgrass Steppe
Vegetation structure plays an important role in determining the abundance and community composition of grassland animals. This is especially relevant in the shortgrass steppe, where grazing by large herbivores may mediate potential climate change-induced increases in the abundance of woody shrubs, potentially altering habitat for rodents. Because rodents are known nest predators, increases in shrub cover that increase rodent abundance may negatively affect nesting birds. My research aim was to determine how rodents respond to vegetation changes caused by herbivores and if these changes increase predation on songbird nests. Over two years, I conducted fieldwork in north-central Colorado within five replicates of long-term experimental plots that manipulated access by large (livestock, pronghorn) and medium-sized mammals (rabbits, prairie dogs). I quantified vegetation cover and herbivore activity in plots, live-trapped rodents to estimate relative abundance, and monitored the survival of artificial nests, some with cameras. Plots that excluded herbivores had higher shrub densities and cover and taller vegetation. Although rodent abundance did not differ significantly between treatments, nocturnal species tended to be more abundant in plots with higher shrub density. Nocturnal species also preferred plots with less shortgrass vegetation, more cacti cover, and taller vegetation. Ground squirrels, mice and, surprisingly, kangaroo rats, preyed upon artificial nests, and rates of nest predation were higher in plots with more rodents. My results may improve our understanding of the indirect effects of shrub encroachment on interactions between rodents and nesting grassland birds in the shortgrass steppe.https://doi.org/10.5281/zenodo.811188
Determination of mass transfer resistances of fast reactions in three-phase mechanically agitated slurry reactors
A methodology for the determination of mass transfer resistances of fast reactions in three-phase mechanically agitated slurry reactors under the reaction conditions is presented. The mass transfer resistances affect significantly the overall mass transfer rate, the design equation and consequently the scale up of the reactor. There is not established methodology to separate the mass transfer resistances under reaction conditions by changing catalyst loading and manipulating the process variables, pressure and agitation speed. This allows to avoid the use of different catalyst particles and give the chance to calculate the mass transfer resistances without caring about the type of catalyst. We calculate each mass transfer resistance under conditions which do not allow to neglect any of the resistances. It is shown that the level off of mass transfer rate which is developed in the plot of mass transfer rate against agitation speed plots is not enough to determine the limiting regime. The hydrogenation of styrene over Pd/C (5% catalyst content) is used as case study to demonstrate the methodology
v-K-ras leads to preferential farnesylation of p21ras in FRTL-5 cells: Multiple interference with the isoprenoid pathway
Italian good practice recommendations on management of persons with Long-COVID
A significant number of people, following acute SARS-CoV-2 infection, report persistent symptoms or new symptoms that are sustained over time, often affecting different body systems. This condition, commonly referred to as Long-COVID, requires a complex clinical management. In Italy new health facilities specifically dedicated to the diagnosis and care of Long-COVID were implemented. However, the activity of these clinical centers is highly heterogeneous, with wide variation in the type of services provided, specialistic expertise and, ultimately, in the clinical care provided. Recommendations for a uniform management of Long-COVID were therefore needed. Professionals from different disciplines (including general practitioners, specialists in respiratory diseases, infectious diseases, internal medicine, geriatrics, cardiology, neurology, pediatrics, and odontostomatology) were invited to participate, together with a patient representative, in a multidisciplinary Panel appointed to draft Good Practices on clinical management of Long-COVID. The Panel, after extensive literature review, issued recommendations on 3 thematic areas: access to Long-COVID services, clinical evaluation, and organization of the services. The Panel highlighted the importance of providing integrated multidisciplinary care in the management of patients after SARS-CoV-2 infection, and agreed that a multidisciplinary service, one-stop clinic approach could avoid multiple referrals and reduce the number of appointments. In areas where multidisciplinary services are not available, services may be provided through integrated and coordinated primary, community, rehabilitation and mental health services. Management should be adapted according to the patient's needs and should promptly address possible life-threatening complications. The present recommendations could provide guidance and support in standardizing the care provided to Long-COVID patients
Inhibition of Hemorragic Snake Venom Components: Old and New Approaches
Snake venoms are complex toxin mixtures. Viperidae and Crotalidae venoms, which are hemotoxic, are responsible for most of the envenomations around the world. Administration of antivenins aimed at the neutralization of toxins in humans is prone to potential risks. Neutralization of snake venom toxins has been achieved through different approaches: plant extracts have been utilized in etnomedicine. Direct electric current from low voltage showed neutralizing properties against venom phospholipase A2 and metalloproteases. This mini-review summarizes new achievements in venom key component inhibition. A deeper knowledge of alternative ways to inhibit venom toxins may provide supplemental treatments to serum therapy
Adaptive Evolution of the Venom-Targeted vWF Protein in Opossums that Eat Pitvipers
The rapid evolution of venom toxin genes is often explained as the result of a biochemical arms race between venomous animals and their prey. However, it is not clear that an arms race analogy is appropriate in this context because there is no published evidence for rapid evolution in genes that might confer toxin resistance among routinely envenomed species. Here we report such evidence from an unusual predator-prey relationship between opossums (Marsupialia: Didelphidae) and pitvipers (Serpentes: Crotalinae). In particular, we found high ratios of replacement to silent substitutions in the gene encoding von Willebrand Factor (vWF), a venom-targeted hemostatic blood protein, in a clade of opossums known to eat pitvipers and to be resistant to their hemorrhagic venom. Observed amino-acid substitutions in venom-resistant opossums include changes in net charge and hydrophobicity that are hypothesized to weaken the bond between vWF and one of its toxic snake-venom ligands, the C-type lectin-like protein botrocetin. Our results provide the first example of rapid adaptive evolution in any venom-targeted molecule, and they support the notion that an evolutionary arms race might be driving the rapid evolution of snake venoms. However, in the arms race implied by our results, venomous snakes are prey, and their venom has a correspondingly defensive function in addition to its usual trophic role
Analisis kuitet Es mayor K. 407 karya Mozart untuk biola, 2 biola alto, horn, cello
Analisis kuintet Es mayor K. 407 merupakan upaya memahami khususnya pribadi Mozart dan pada umumnya periode Klasik, analisi ini memberikan persepsi tentang pribado Mozart menghadapi kehidupannya
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