Darwinian transformation of a 'scarcely nutritious fluid' into milk

In an early challenge to an aspect of Darwin’s theory of natural selection, Jackson Mivart contended that milk could not have evolved ‘from a scarcely nutritious fluid from an accidentally hypertrophied cutaneous gland’. The evolutionary change from a gland secretion to milk involves an increase in calcium and protein concentrations by up to 100- and 1000-fold, respectively. Even so, the challenge, we suggest, is not just a problem of scale. An increase in the concentrations of calcium and phosphate brings an increased risk of calcification of the secretory gland because calcium phosphate is highly insoluble. In addition, two of the four constituent milk casein proteins (κ and αS2) aggregate to produce toxic amyloid fibrils. It is proposed that both problems were solved through the cosecretion of ancestral β- and κ-caseins to form a stable amorphous aggregate of both proteins with sequestered amorphous calcium phosphate, that is, a primordial casein micelle. Evolutionarily, a gradual increase in the concentration of casein micelles could therefore produce progressively more nutritious fluids for the neonate without endangering the reproductive potential of the mother

Resting respiratory tract dendritic cells preferentially stimulate T helper cell Type 2(Th2) responses and require obligatory cytokine signals for induction of Th1 immunity

Consistent with their role in host defense, mature dendritic cells (DCs) from central lymphoid organs preferentially prime for T helper cell type 1 (Th1)-polarized immunity. However, the “default” T helper response at mucosal surfaces demonstrates Th2 polarity, which is reflected in the cytokine profiles of activated T cells from mucosal lymph nodes. This study on rat respiratory tract DCs (RTDCs) provides an explanation for this paradox. We demonstrate that freshly isolated RTDCs are functionally immature as defined in vitro, being surface major histocompatibility complex (MHC) II lo, endocytosishi, and mixed lymphocyte reactionlo, and these cells produce mRNA encoding interleukin (IL)-10. After ovalbumin (OVA)-pulsing and adoptive transfer, freshly isolated RTDCs preferentially stimulated Th2-dependent OVA-specific immunoglobulin (Ig)G1 responses, and antigen-stimulated splenocytes from recipient animals produced IL-4 in vitro. However, preculture with granulocyte/macrophage colony stimulating factor increased their in vivo IgG priming capacity by 2–3 logs, inducing production of both Th1- and Th2-dependent IgG subclasses and high levels of IFN-γ by antigen-stimulated splenocytes. Associated phenotypic changes included upregulation of surface MHC II and B7 expression and IL-12 p35 mRNA, and downregulation of endocytosis, MHC II processing– associated genes, and IL-10 mRNA expression. Full expression of IL-12 p40 required additional signals, such as tumor necrosis factor α or CD40 ligand. These results suggest that the observed Th2 polarity of the resting mucosal immune system may be an inherent property of the resident DC population, and furthermore that mobilization of Th1 immunity relies absolutely on the provision of appropriate microenvironmental costimuli

Shearing Lambs Improves Growth Performance During Periods with Elevated Thermal Load

The purpose of this study was to determine if average daily gain (ADG) is improved in shorn lambs versus non-shorn lambs in the summer months in the upper Midwestern United States. Forty-nine purebred Hampshire and Columbia ram (n = 10 Hampshire and 4 Columbia) and ewe (n = 22 Hampshire and 13 Columbia) lambs were grouped by breed, sex, age (104 ± 1.7 days of age), and initial weight (109 ± 3.5 lbs) into shorn (n=26) and non-shorn (n=23) groups. After shearing (3 June 2004), shorn sheep had approximately 0.1 inches of wool-cover. Lambs were weighed 1, 29, and 57 days following shearing. During the first 28 day period following shearing (period 1), there was no difference in average daily gain between shorn and non-shorn lambs (0.8 ± 0.04 vs 0.82 ± 0.04 lbs/day, respectively). In the second 28 day period (period 2), shorn lambs had a greater average daily gain than non-shorn lambs (1.02 ± 0.06 vs 0.92 ± 0.06 lbs/day, respectively). Period 2 had greater mean (68.9 vs. 63.4 oF, respectively), minimum (59.7 vs 54.1oF, respectively), and maximum (78.2 vs. 73.8oF, respectively) daily ambient air temperature and greater mean humidity (73.97 vs. 68.2 %, respectively) than period 1. The calculated temperature humidity index (THI) was also greater in period 2 than period 1 (66.9 vs. 62.24, respectively). These data indicate that shorn lambs grow more rapidly than non-shorn lambs during periods of elevated temperature, humidity, and THI

3D acoustic-structure interaction of ultrasound in fluids for the manufacture of graded materials

Functionally graded materials engineered to meet specific requirements are being increasingly sought after for advanced engineering projects, yet the possibilities for their manufacture lag behind their design. The ability to control the porosity of a cellular material is one such method for adding functional gradients within materials. A novel technique using ultrasound to control the porosity in reacting polymers shows potential to effectively mass-manufacture porosity tailored polymeric foams. In this work the pressure field in a metastable polymer produced by multiple ultrasonic sources is modeled at distinct stages of the polymerisation reaction

Invited review: Modeling milk stability

Novel insights into the stability of milk and milk products during storage and processing result from describing caseins near neutral pH as hydrophilic, intrinsically disordered, proteins. Casein solubility is strongly influenced by pH and multivalent ion binding. Solubility is high at neutral pH or above but decreases as casein net charge approaches zero, allowing a condensed casein phase or gel to form then increases at lower pH. Of particular importance for casein micelle stability near neutral pH is the proportion of free caseins in the micelle (i.e., caseins not bound directly to nanoclusters of calcium phosphate). Free caseins are more soluble and better able to act as molecular chaperones (to prevent casein and whey protein aggregation) than bound caseins. Some free caseins are highly phosphorylated and can also act as mineral chaperones to inhibit the growth of calcium phosphate phases and prevent mineralized deposits from forming on membranes or heat exchangers. Thus, casein micelle stability is reduced when free caseins bind to amyloid fibrils, destabilized whey proteins or calcium phosphate. The multivalent-binding model of the casein micelle quantitatively describes these and other factors affecting the stability of milk and milk protein products during manufacture and storage

Search for the hero: an investigation into the sports heroes of British sports fans

This is an initial study into British sports fans’ heroes. A questionnaire was sent to 95 students (average age ¼ 19.75) to identify their sporting hero, the hero’s sport and nationality and the reasons for this choice. Football was the most common source of sports heroes, identified by 49% of participants with a sporting hero. The majority (60%, N ¼ 48) of heroes chosen by participants were British, with David Beckham the most popular choice. Differences were observed between the gender of participants, gender of hero chosen and the reasons for choosing the hero. The most common reason for selecting a hero was a personal trait rather than skill, while in the questionnaire a category of Local Affiliation was added to those suggested by previous work. It was concluded that to become a hero athletes should combine skill with devotion to family, charity work and a place in popular culture

An update on the Hirsch conjecture

The Hirsch conjecture was posed in 1957 in a letter from Warren M. Hirsch to George Dantzig. It states that the graph of a d-dimensional polytope with n facets cannot have diameter greater than n - d. Despite being one of the most fundamental, basic and old problems in polytope theory, what we know is quite scarce. Most notably, no polynomial upper bound is known for the diameters that are conjectured to be linear. In contrast, very few polytopes are known where the bound $n-d$ is attained. This paper collects known results and remarks both on the positive and on the negative side of the conjecture. Some proofs are included, but only those that we hope are accessible to a general mathematical audience without introducing too many technicalities.Comment: 28 pages, 6 figures. Many proofs have been taken out from version 2 and put into the appendix arXiv:0912.423

An Alternative Method to Deduce Bubble Dynamics in Single Bubble Sonoluminescence Experiments

In this paper we present an experimental approach that allows to deduce the important dynamical parameters of single sonoluminescing bubbles (pressure amplitude, ambient radius, radius-time curve) The technique is based on a few previously confirmed theoretical assumptions and requires the knowledge of quantities such as the amplitude of the electric excitation and the phase of the flashes in the acoustic period. These quantities are easily measurable by a digital oscilloscope, avoiding the cost of expensive lasers, or ultrafast cameras of previous methods. We show the technique on a particular example and compare the results with conventional Mie scattering. We find that within the experimental uncertainties these two techniques provide similar results.Comment: 8 pages, 5 figures, submitted to Phys. Rev.

Athlete experiences of disordered eating in sport

To date, research into disordered eating in sport has focused on the prevalence and the identification of putative risk factors. Findings suggest that elite female athletes participating in sports with a focus on leanness or aesthetics are at greatest risk. A paucity of research remains as to the period after onset and how existing sufferers manage their illness over time. In line with the principles of interpretative phenomenological analysis (IPA), this study 'gives voice' to four athletes who have experienced disordered eating, documenting their personal accounts and interpreting these accounts from a psychological perspective. In‐depth, semi‐structured interviews were conducted and verbatim transcripts were analysed according to the procedures of IPA. Three superordinate themes emerged from the data: the struggle to disclose, social support needs and identity challenges. Athletes' stories provided rich descriptions of their subjective disordered eating experiences. Their accounts give critical insight into the impact of eating disturbance on the lives of athletes. Future research should continue to identify athletes with existing eating problems in order to improve understanding as to how such individuals can best be helped

VIM-positive Pseudomonas aeruginosa in a large tertiary care hospital: Matched case-control studies and a network analysis

Background: Emergence of multidrug-resistant Pseudomonas aeruginosa is of global concern. We aimed to identify epidemiological relationships, the most common way of transmission, and risk factors for presence of Verona Integron-encoded Metallo-β-lactamase (VIM)-positive P. aeruginosa (VIM-PA). Methods: We conducted a network analysis and matched case-control studies (1:2:2). Controls were hospital-based and matched with cases for ward, day of admission (control group 1 and 2) and time between admission and the identification of VIM-PA (control group 1). The network was visualized using Cytoscape, an