Superior signal persistence of circularly polarized light in polydisperse, real-world fog environments.

We present simulation results quantitatively showing that circularly polarized light persists in transmission through several real-world and model fog environments better than linearly polarized light over broad wavelength ranges from the visible through the infrared. We present results for polydisperse particle distributions from realistic and measured fog environments, comparing the polarization persistence of linear and circular polarization. Using a polarization-tracking Monte Carlo program, we simulate polarized light propagation through four MODTRAN fog models (moderate and heavy radiation fog and moderate and heavy advection fog) and four real-world measured fog particle distributions (Garland measured radiation and advection fogs, Kunkel measured advection fog, and Sandia National Laboratories' Fog Facility's fog). Simulations were performed for each fog environment with wavelengths ranging from 0.4 to 12 µm for increasing optical thicknesses of 5, 10, and 15 (increasing fog density or sensing range). Circular polarization persists superiorly for all optical wavelength bands from the visible to the long-wave infrared in nearly all fog types for all optical thicknesses. Throughout our analysis, we show that if even a small percentage of a fog's particle size distribution is made up of large particles, those particles dominate the scattering process. In nearly all real-world fog situations, these large particles and their dominant scattering characteristics are present. Larger particles are predominantly forward-scattering and contribute to circular polarization's persistence superiority over broad wavelength ranges and optical thicknesses/range. Circularly polarized light can transmit over 30% more signal in its intended state compared to linearly polarized light through real-world fog environments. This work broadens the understanding of how circular polarization persists through natural fog particle distributions with natural variations in mode particle radius and single or bimodal characteristics.

Effects of increased milking frequency during early lactation on milk yield and udder health of primiparous Holstein heifers.

In dairy cows, increased milking frequency (IMF) during early lactation stimulates an increase in milk yield that partially persists through the remainder of lactation. However, the effects of IMF on lactation performance and udder health of primiparous heifers have not been clearly established. The objective of this study was to determine the effects of IMF during early lactation on milk yield and composition, udder edema, and teat-end condition of primiparous Holstein heifers. Thirteen heifers were assigned at parturition to unilateral frequent milking (twice-daily milking of the left udder half (2X), and 4-times-daily milking of the right udder half (4X)) from d 1 to 21 of lactation. Heifers were milked twice daily at 0130 and 1330 h, with additional milking of the right udder half at 0430 and 1630 h. Half-udder milk yield and composition were recorded on d 1 and 4, weekly through 35 d in milk (DIM), monthly through 210 DIM, and on d 270±1 of lactation. Udder edema and teat-end scores were evaluated on d 1 and 4, weekly through d 35, and on d 60±1 of lactation. A 1-sided paired t test was used to compare milk yield of 4X- to 2X-udder halves. A 2-sided paired t test was used to test for differences in milk composition, udder edema, and teat-end scores. Overall, 4X stimulated an immediate increase in milk yield. Differential milk yield peaked on d 21 of lactation, with 4X udder halves producing 2.8 kg/d more milk than 2X udder halves (P<0.001). After cessation of 4X, the milk yield differential decreased, but 4X udder halves continued to produce 0.8 kg/d more milk than 2X udder halves through d 270 of lactation (P<0.05). Over the entire lactation, milk component yields and 3.5% fat-corrected milk or energy-corrected milk were greater (P<0.05), whereas somatic cell counts in milk were lower, in 4X udder halves (P<0.05). Udder edema and teat-end condition did not differ between 4X and 2X (P>0.19). In conclusion, IMF during early lactation stimulated a persistent increase in milk yield without negatively affecting several indicators of udder health of primiparous dairy heifers.

A survey of trainee obstetricians preferences for childbirth.

OBJECTIVE: To determine trainee obstetricians personal preferences regarding mode and place of delivery given various scenarios. STUDY DESIGN: An anonymous nationwide postal survey of 365 specialist registrars. RESULTS: The response rate was 76%. About 2.5% preferred a home birth. And 16% of men and 15% of women opted for elective cesarean section (CS). When faced with a proposed trial of instrumental delivery in theatre, 60% accepted and a further 12% accepted only if they could choose the obstetrician performing the delivery. Regarding a breech presentation at term, 78% would accept external cephalic version (ECV). CONCLUSIONS: The percentage of obstetricians who preferred vaginal delivery and ECV were considerably higher than previously reported, and there were no significant gender differences. This study shows a more balanced attitude from obstetricians and refutes the previously held view that they necessarily advocate high levels of intervention for themselves.

The pig as a model for excisional skin wound healing: characterization of the molecular and cellular biology, and bacteriology of the healing process.

A pig model of wound healing was developed by excision of 2-cm-diameter full thickness skin in young Yorkshire pigs. The results indicated that wound re-epithelialization in this animal model took an average of 20 days. Analysis of cellular change was assessed by use of DNA quantification and determination of apoptotic cells in tissue sections. The results indicate that RNA and DNA contents paralleled each other throughout the healing process, and observed changes in the pattern of RNA and DNA content of the scar tissues were consistent with cell loss due to apoptosis in this model. Expression of mRNA for relevant genes was assessed by use of semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) analysis, using porcine specific primer sets and RNA isolated from normal skin and specimens obtained at various times after wounding. The mRNA values for tumor necrosis factor-alpha (TNF-alpha), connective tissue growth factor (CTGF), insulin-like growth factor II (IGF-II), and decorin were significantly high at specific times after wounding, but mRNA values for the transcription factors (c-fos and c-jun) were significantly decreased. Quantitative bacteriologic results indicated that the total bacterial count in this animal model reached 10(9) colony-forming units (CFU)/g, with the highest value at post-wounding day 7, and Pseudomonas aeruginosa and Staphylocococci aureus were the most common bacteria detected in this model. Further definition of this model should identify unique points in the healing process, and such information could lead to development of therapeutic interventions to improve skin wound healing.

Healing of porcine donor sites covered with silver-coated dressings.

OBJECTIVE: To compare rates of healing of donor sites in pigs between those dressed with silver-coated dressings and those dressed with petrolatum-impregnated absorbent gauze. DESIGN: Open study with each animal acting as its own control. SETTING: University research facility, Canada. ANIMALS: 6 young specific-pathogen-free domestic pigs. INTERVENTIONS: A total of 72 wounds about 1 cm x 2 cm x 0.4 mm were made in rows of eight on each pig with a dermatome. They were divided into three groups of 24, and dressed with petrolatum gauze, or silver-coated dressings moistened with sterile water either once only or daily for 10 days. All dressings were secured in place with an elastic bandage. MAIN OUTCOME MEASURES: Erythema, infection, epidermal migration, and healing. RESULTS: Wounds dressed with moistened silver-coated dressings re-epithelialised significantly more quickly. This resulted in complete re-epithelialisation within 70% of the time taken by those wounds dressed with petrolatum gauze. CONCLUSION: Silver-coated dressings provide a moist environment for the healing wound combined with an effective antimicrobial agent, and this significantly accelerates healing compared with wounds dressed with traditional petrolatum gauze dressings.

Molecular and cell biology of skin wound healing in a pig model.

To define the pattern of change at the molecular and cellular levels during the healing of excisional skin wounds in the skeletally immature pig, mRNA levels for relevant molecules were assessed by semiquantitative RT-PCR using porcine specific primer sets and RNA isolated from normal skin and samples at various time post-wounding. Analysis of cellular change was assessed by DNA quantification and histology of tissue sections. The results demonstrated that the changes in the pattern of RNA and DNA content of the scar tissue were consistent with the observed increasing cellularity. The mRNA levels for collagen I, III, HSP47, IL-1, TGF-beta, MMP-1, -2 and -9, TIMP-1, -2, and-4, PAI-1, versican were significantly elevated during healing; levels for biglycan and fibromodulin were not significantly altered; and the mRNA levels for TIMP-3 were depressed. These findings suggest that skin wound healing is a series of complex matrix-cell interactions that involve cellular migration and inflammation, followed by proliferation of fibroblasts with new collagen synthesis, and lastly tissue remodeling of the scar.

Fragmentation of an alkali metal-attached peptide probed by collision-induced dissociation fourier transform mass spectrometry and computational methodology.

Collision-induced dissociation of metal-cationized N-CBZ-Gly-Pro-Gly-Pro-Ala was studied by Fourier transform mass spectrometry. Lithium-, sodium-, potassium- and rubidium-cationized peptide species were generated by matrix-assisted laser desorption/ionization (MALDI) using 2,5-dihydroxybenzoic acid as matrix, together with appropriate metal salts. The experimental mass spectrometric results were interpreted with the aid of Monte Carlo conformational searches using the Amber(*) force field, together with ab initio molecular orbital calculations with Gaussian-94 for the singly lithium- and potassium-cationized peptides. It is concluded that metal coordination plays a key role in guiding the gas-phase fragmentation of the cationized peptide. In contrast to lithium and sodium, potassium and rubidium apparently do not coordinate to the C-terminal carbonyl. When the peptide is cationized with the two smaller alkali metals, losses corresponding to alanine and CBZ are observed, while the coordination of potassium and rubidium results in only CBZ loss upon dissociation.

Efficacy of topical silver against fungal burn wound pathogens.

BACKGROUND: Fungal infections of burn wounds have become an important cause of burn-associated morbidity and mortality. The nature of fungal infections dictates aggressive treatment to minimize the morbidity associated with these infections. Persons with large total body surface area burns are particularly susceptible to fungal infections and are treated in such a manner as to minimize their risk of infection. METHODS: This study examined the in vitro fungicidal efficacy of a variety of different topical agents. By placing fungal inocula in contact with mafenide acetate, silver nitrate, silver sulfadiazine, and a nanocrystalline silver-coated dressing, we determined the kill kinetics of these topical agents against a spectrum of common burn wound fungal pathogens. RESULTS: The topical antimicrobials that were tested demonstrated varying degrees of efficacy against these pathogens. CONCLUSION: The nanocrystalline silver-based dressing provided the fastest and broadest-spectrum fungicidal activity and may make it a good candidate for use to minimize the potential of fungal infection, thereby reducing complications that delay wound healing.

Analysis of VX on soil particles using ion trap secondary ion mass spectrometry.

The direct detection of the nerve agent VX (methylphosphonothioic acid, S-[2-[bis(1-methylethyl)amino]ethyl] O-ethyl ester) on milligram quantities of soil particles has been achieved using ion trap secondary ion mass spectrometry (IT-SIMS). VX is highly adsorptive toward a wide variety of surfaces; this attribute makes detection using gas-phase approaches difficult but renders the compound very amenable to surface detection. An ion trap mass spectrometer, modified to perform SIMS, was employed in the present study. A primary ion beam (ReO4-) was fired on axis through the ion trap, where it impacted the soil particle samples. [VX + H]+, [VX + H]+ fragment ions, and ions from the chemical background were sputtered into the gas-phase environment of the ion trap, where they were either scanned out or isolated and fragmented (MS2). At a surface concentration of 0.4 monolayer, intact [VX + H]+, and its fragment ions, were readily observable above background. However, at lower concentrations, the secondary ion signal from VX became obscured by ions derived from the chemical background on the surface of the soil particles. MS2 analysis using the ion trap was employed to improve detection of lower concentrations of VX: detection of the 34S isotopic ion of [VX + H]+, present at a surface concentration of approximately 0.002 monolayer, was accomplished. The study afforded the opportunity to investigate the fragmentation chemistry of VX. Semiempirical calculations suggest strongly that the molecule is protonated at the N atom. Deuterium labeling showed that formation of the base peak ion (C2H4)N(i-C3H7)2+ involves transfer of the amino proton to the phosphonothioate moiety prior to, or concurrent with, C-S bond cleavage. To manage the risk associated with working with the compound, the vacuum unit of the IT-SIMS was located in a hood, connected by cables to the externally located electronics and computer.

Wound management in an era of increasing bacterial antibiotic resistance: a role for topical silver treatment.

BACKGROUND: Antibiotic-resistant bacteria represent an increasing concern in wound infections. Wound colonization with these organisms normally results in aggressive management of the wound complicated by a greatly limited choice of therapeutic antibiotics. Silver and other noble metals are recognized as potential allies in combating these organisms in wounds. METHODS: Three types of topical silver applications were tested to determine their bactericidal efficacies against clinical isolates of antibiotic-resistant organisms. The silver-based applications represent 3 methods of applying silver to wounds: as a liquid (silver nitrate), incorporated in a cream (silver sulfadiazine) and as a dressing coating (silver-coated dressings). The reduction in the viable bacterial population recovered from test articles after exposure to silver provided a comparative measure of the bactericidal efficacies of these silver applications. RESULTS: All of the products demonstrated an ability to reduce the number of viable bacteria. However, the methods varied in their efficacy against antibiotic-resistant bacteria, with the silver-coated dressing being the most efficacious and silver nitrate the least efficacious. CONCLUSIONS: Silver was demonstrated to be effective at killing the antibiotic-resistant strains tested. The silver-coated dressing was particularly rapid at killing the tested bacteria and was effective against a broader range of bacteria. Silver may be a useful prophylactic or therapeutic agent for the prevention of wound colonization by organisms that impede healing, including antibiotic-resistant bacteria.

Gravitropism in roots of intermediate-starch mutants of Arabidopsis.

Gravitropism was studied in roots of wild type (WT) Arabidopsis thaliana (L.) Heynh. (strain Wassilewskija) and three starch-deficient mutants that were generated by T-DNA insertional mutagenesis. One of these mutants was starchless while the other two were intermediate mutants, which had 51% and 60%, respectively, of the WT amount of starch as determined by light and electron microscopy. The four parameters used to assay gravitropism were: orientation during vertical growth, time course of curvature, induction, and intermittent stimulation experiments. WT roots were much more responsive to gravity than were roots of the starchless mutant, and the intermediate starch mutants exhibited an intermediate graviresponse. Our data suggest that lowered starch content in the mutants primarily affects gravitropism rather than differential growth because both phototropic curvature and growth rates were approximately equal among all four genotypes. Since responses of intermediate-starch mutants were closer to the WT response than to the starchless mutant, it appears that 51-60% of the WT level of starch is near the threshold amount needed for full gravitropic sensitivity. While other interpretations are possible, the data are consistent with the starch statolith hypothesis for gravity perception in that the degree of graviresponsiveness is proportional to the total mass of plastids per cell.

Psychological aspects of heavy periods: does endometrial ablation provide the answer?

Menorrhagia may sometimes represent psychological problems. A frequent gynaecological response to this complaint is surgery. More recently, psychological factors and accurate assessment of menstrual loss have called into question the need for hysterectomy in a proportion of women. Endometrial ablation offers a less invasive alternative to hysterectomy which may result in a better psychological outcome.

Wild water rapid burns.

Swimming pool water slides are becoming increasingly long and adventurous. This case report and survey suggest that they may carry with them a notable risk of friction burns.