Carrying Capacity of Ranges in Western United States

Few persons realize the importance, necessity and far reaching results of proper range management. There was a time on the Western ranges when 2 or 3 acres of grass land would support a cow or horse. At the present time, 20 to 30 acres per head are needed on the same area. Had the stockman of those days applied some of the principles his neighboring farmers were applying, perhaps unknowingly, he would have maintained the productivity of the range and would have benefited the present generation in lower beef prices. However, let it be said in defense of the cattleman of that day, he was only human. Perhaps anyone seeing the wonderful and abundant forage which covered the West, would have been prompted with the same get-rich-quick motives and have exploited the range to its capacity and over and then left the future to care for itself. Years after the ranges were overstocked, state legislatures passed various laws concerning the grazing of stock on public ranges and finally, with the creation of National Forests, many ranges came under the more rational systems now being used by the Forest Service. In a way, it is safe to say that the methods of handling stock are still in their infancy and are still extensive although some of them are called intensive

Maximum occupation number for composite boson states

One of the major differences between fermions and bosons is that fermionic states have a maximum occupation number of one, whereas the occupation number for bosonic states is in principle unlimited. For bosons that are made up of fermions, one could ask the question to what extent the Pauli principle for the constituent fermions would limit the boson occupation number. Intuitively one can expect the maximum occupation number to be proportional to the available volume for the bosons divided by the volume occupied by the fermions inside one boson, though a rigorous derivation of this result has not been given before. In this letter we show how the maximum occupation number can be calculated from the ground-state energy of a fermionic generalized pairing problem. A very accurate analytical estimate of this eigenvalue is derived. From that a general expression is obtained for the maximum occupation number of a composite boson state, based solely on the intrinsic fermionic structure of the bosons. The consequences for Bose-Einstein condensates of excitons in semiconductors and ultra cold trapped atoms are discussed.Comment: 4 pages, Revte

The Making of an Ames Forester

Foremost among the movements for a better forestry course at Ames, is that for the establishment of a summer camp at the close of the Freshman year. This plan is in perfect keeping with the Ames motto of Science with Practice in that half a year\u27s work has been transferred to the woods, where actual forest conditions exist

Prewetting transition on a weakly disordered substrate : evidence for a creeping film dynamics

We present the first microscopic images of the prewetting transition of a liquid film on a solid surface. Pictures of the local coverage map of a helium film on a cesium metal surface are taken while the temperature is raised through the transition. The film edge is found to advance at constant temperature by successive avalanches in a creep motion with a macroscopic correlation length. The creep velocity varies strongly in a narrow temperature range. The retreat motion is obtained only at much lower temperature, conforming to the strong hysteresis observed for prewetting transition on a disordered surface. Prewetting transition on such disordered surfaces appears to give rise to dynamical phenomena similar to what is observed for domain wall motions in 2D magnets.Comment: 7 pages, 3 figures, to be published in Euro.Phys.Let

Medical student self-efficacy, knowledge and communication in adolescent medicine

Objectives To evaluate student self-efficacy, knowledge and communication with teen issues and learning activities. Methods Data were collected during the 8-week pediatric rotation for third–year medical students at a local children’s hospital. Students completed a self-efficacy instrument at the beginning and end of the rotation; knowledge and communication skills were evaluated during standardized patient cases as part of the objective structured clinical examination. Self-efficacy, knowledge and communication frequencies were described with descriptive statistics; differences between groups were also evaluated utilizing two-sample t-tests. Results Self-efficacy levels of both groups increased by the end of the pediatric rotation, but students in the two-lecture group displayed significantly higher self-efficacy in confidentiality with adolescents (t(35)=-2.543, p=0.02); interviewing adolescents, assessing risk, sexually transmitted infection risk and prevention counseling, contraception counseling were higher with marginal significance. No significant differences were found between groups for communication; assessing sexually transmitted infection risk was marginally significant for knowledge application during the clinical exam. Conclusions Medical student self-efficacy appears to change over time with effects from different learning methods; this higher self-efficacy may increase future comfort and willingness to work with this high-risk, high-needs group throughout a medical career

More like him, me, or us: the impact of trait similarity on adolescent women’s sexual risk behaviors in relationships

Ideal partner traits and how they relate to a young woman’s current partner and relationship is a knowledge gap in the literature. The objectives of this study were 1) to assess any differences in interpersonal characteristics between a young woman or her partner and relationship and 2) to examine the impact of this difference on sexual monogamy, condom use and frequency of vaginal sex. Study participants (n=387, 14–17 years at enrollment, 90% African American) were recruited from three primary care adolescent health clinics serving areas with high rates of unintended pregnancy and sexually transmitted infection (STI); data were drawn from a longitudinal cohort study of sexual relationships and behaviors among young women. Nineteen interpersonal characteristics, including physical, financial, communication and personal characteristic variables, were found to have varying influences on relationships and sexual behaviors with ‘like him’ and ‘like us’ as referents. Monogamy increased as a male partner wanted to get somewhere in life [OR 5.41, (1.25, 23.52, p<0.05)], was intelligent [OR 3.42, (1.09, 10.76, p<0.05)] and had money [OR 1.55, (0.272, 0.595, p<0.001)] in a partnership; monogamy similarly increased when a partner wanted to get somewhere in life [OR 6.77, (1.51, 30.36, p<0.01)], was intelligent [OR 4.02, (1.23, 13.23, p<0.05)], and had money [OR 2.41, (1.51, 3.84, p<0.001)] compared to the young woman. The likelihood of using a condom at last sex increased when the male partner had a nice body [OR 1.42, (1.02, 1.99, p<0.05)], was popular [OR 1.60, (1.12, 2.29, p<0.01)], cared for others [OR 3.43, (1.32, 8.98, p<0.01)], was good at sports [OR 1.35, (1.06, 1.73, p<0.05)] and expressed his feelings [OR 2.03, (1.14, 3.60, p<0.01)]. The condom use ratio increased when the male partner was able to take care of himself [OR 0.076, (0.017, 0.136, p<0.01)], was cute [OR 0.190, (0.082, 0.30, p<0.001)], and had a nice body [OR 0.044, (0.001, 0.09, p<0.05)] in a dyad; the condom use ratio also increased when a male partner could take care of himself [OR 0.091, (0.014, 0.168, p<0.05)], was cute [OR 0.194, (0.077, 0.311, p<0.001)] compared to the young woman. Coital frequency increased when the male partner was described as being able to take care of himself [OR 3.33, (0.138, 6.52, p<0.05)]. Such influences are important in discussions with young women regarding personal and partner choices in sexual health as partners, behaviors and motivations for choice frequently change

Hydrodynamic object recognition using pressure sensing

Hydrodynamic sensing is instrumental to fish and some amphibians. It also represents, for underwater vehicles, an alternative way of sensing the fluid environment when visual and acoustic sensing are limited. To assess the effectiveness of hydrodynamic sensing and gain insight into its capabilities and limitations, we investigated the forward and inverse problem of detection and identification, using the hydrodynamic pressure in the neighbourhood, of a stationary obstacle described using a general shape representation. Based on conformal mapping and a general normalization procedure, our obstacle representation accounts for all specific features of progressive perceptual hydrodynamic imaging reported experimentally. Size, location and shape are encoded separately. The shape representation rests upon an asymptotic series which embodies the progressive character of hydrodynamic imaging through pressure sensing. A dynamic filtering method is used to invert noisy nonlinear pressure signals for the shape parameters. The results highlight the dependence of the sensitivity of hydrodynamic sensing not only on the relative distance to the disturbance but also its bearing

Std fimbriae-fucose interaction increases Salmonella-induced intestinal inflammation and prolongs colonization

Author summary The intestinal epithelium is a crucial biological interface, interacting with both commensal and pathogenic microorganisms. It’s lined with heavily glycosylated proteins and glycolipids which can act as both attachment sites and energy sources for intestinal bacteria. Fut2, the enzyme governing epithelial α1,2-fucosylation, has been implicated in the interaction between microbes and intestinal epithelial cells. Salmonella is one of the most important bacterial gastrointestinal pathogens affecting millions of people worldwide. Salmonella possesses fimbrial and non-fimbrial adhesins which can be used to adhere to host cells. Here we show that Salmonella expresses Std fimbriae in the gastrointestinal tract in vivo and exploit Std fimbriae to bind fucosylated structures in the mucus and on the intestinal epithelium. Furthermore, we demonstrate that the Std fimbriae-fucose interaction is necessary for bacterial colonization of the intestine and for triggering intestinal inflammation. These data lend new insights into bacterial adhesion-epithelial interactions which are essential for bacterial pathogenesis and key factors in determining tissue tropism and host susceptibility to infectious disease