Plasma emission characteristics in laser-induced breakdown spectroscopy of silicon with mid-infrared, multi-millijoule, nanosecond laser pulses from a Ho:YLF excitation source.

We characterized the plasma emission produced by the interaction of multi-millijoule, 40 ns duration, mid-infrared laser pulses with a silicon surface. The laser pulses were produced by a Q-switched Ho:YLF master oscillator power amplifier system. Using spectral measurements and a framing camera, we observed a spatial separation of the plasma plume, increased emission signal with low white-light generation, and a drop in the time- and space-averaged apparent plasma density with increasing pump energy. Our results can be explained by continuous heating of the plasma by the pump pulse due to the more efficient inverse bremsstrahlung absorption at longer wavelengths.

Determining the sources of nutrient flux to water in headwater catchments: Examining the speciation balance to inform the targeting of mitigation measures.

Diffuse water pollution from agriculture (DWPA) is a major environmental concern, with significant adverse impacts on both human and ecosystem health. However, without an appropriate understanding of the multiple factors impacting on water, mitigation measures cannot be targeted. Therefore, this paper addresses this gap in understanding, reporting the hydrochemical monitoring evidence collected from the UK Government's Demonstration Test Catchments (DTC) programme including contrasting chalk and clay/mudstone catchments. We use data collected at daily and sub-daily frequency over multiple sites to address: (1) How does the behaviour of the full range of nitrogen (N) species and phosphorus (P) fractions vary? (2) How do N species and P fractions vary inter- and intra-annually? (3) What do these data indicate about the primary pollution sources? And (4) which diffuse pollution mitigation measures are appropriate in our study landscapes? Key differences in the rates of flux of nutrients were identified, dependent on catchment characteristics. Full N speciation and P fractionation, together with dissolved organic carbon (DOC) enabled identification of the most likely contributing sources in each catchment. Nitrate (NO3-N) was the dominant N fraction in the chalk whereas organic and particulate N comprised the majority of the load in the clay/mudstone catchments. Despite current legislation, orthophosphate (PO4-P) was not found to be the dominant form of P in any of the catchments monitored. The chalk sub-catchments had the largest proportion of inorganic/dissolved organic P (DOP), accompanied by episodic delivery of particulate P (PP). Contrastingly, the clay/mudstone sub-catchments loads were dominated by PP and DOP. Thus, our results show that by monitoring both the inorganic and organic fractions a more complete picture of catchment nutrient fluxes can be determined, and sources of pollution pin-pointed. Ultimately, policy and management to bring nutrient impacts under control will only be successful if a multi-stressor approach is adopted.

A prospective observational study of the association between cabin and outside air temperature, and patient temperature gradient during helicopter transport in New South Wales.

The prevalence of hypothermia in patients following helicopter transport varies widely. Low outside air temperature has been identified as a risk factor. Modern helicopters are insulated and have heating; therefore outside temperature may be unimportant if cabin heat is maintained. We sought to describe the association between outside air, cabin and patient temperature, and having the cabin temperature in the thermoneutral zone (18-36°C) in our helicopter-transported patients. We conducted a prospective observational study over one year. Patient temperature was measured on loading and engines off. Cabin and outside air temperature were recorded for the same time periods for each patient, as well as in-flight. Previously identified risk factors were recorded. Complete data was obtained for 133 patients. Patients' temperature increased by a median of 0.15°C (P=0.013). There was no association between outside air temperature or cabin temperature and patient temperature gradient. The best predictor of patient temperature on landing was patient temperature on loading (R2=0.86) and was not improved significantly when other risk factors were added (P=0.63). Thirty-five percent of patients were hypothermic on loading, including those transferred from district hospitals. No patient loaded normothermic became hypothermic when the cabin temperature was in the thermoneutral zone (P=0.04). A large proportion of patients in our sample were hypothermic at the referring hospital. The best predictor of patient temperature on landing is patient temperature on loading. This has implications for studies that fail to account for pre-flight temperature.

High-sensitivity ring-down evanescent-wave sensing in fiber resonators.

We report on optical-fiber cavity ring-down spectroscopy (CRDS) in the liquid phase using a laser emitting at telecommunication wavelengths. A fiber-ring cavity, comprising a short evanescent-wave coupler for radiation-matter interaction, is used as a sensor while its resonance modes are frequency locked to the laser. Exploiting the intrinsic sensitivity and noise immunity of the CRDS technique, we show that liquid absorption can be detected down to a level that is nearly a factor of 20 above the shot noise limit. We provide a thorough comparison between the experimental results and various noise contributions and address different expressions that can be used to calculate the shot noise equivalent absorbance. As a proof of principle, polyamine detection in aqueous solutions is carried out demonstrating a minimum detectable absorbance of 1.8×10(-7) Hz(-1/2), which, to our knowledge, is the best sensitivity limit reported to date for evanescent-wave sensors.

Impact of podiatry resident experience level in hallux valgus surgery on postoperative outcomes.

BACKGROUND: Despite modern advancements in transosseous fixation and operative technique, hallux valgus (i.e., bunion) surgery is still associated with a higher than usual amount of patient dissatisfaction and is generally recognized as a complex and nuanced procedure requiring precise osseous and capsulotendon balancing. It stands to reason then that familiarity and skill level of trainee surgeons might impact surgical outcomes in this surgery. The aim of this study was to determine whether podiatry resident experience level influences midterm outcomes in hallux valgus surgery (HVS). METHODS: Consecutive adults who underwent isolated HVS via distal metatarsal osteotomy at a single US metropolitan teaching hospital from January 2004 to January 2009 were contacted and asked to complete a validated outcome measure of foot health (Manchester-Oxford Foot Questionnaire) regarding their operated foot. Resident experience level was quantified using the surgical logs for the primary resident of record at the time of each case. Associations were assessed using linear and logistic regression analyses. RESULTS: A total of 102 adult patients (n = 102 feet) agreed to participate with a mean age of 46.8 years (standard deviation 13.1, range 18-71) and average length of follow-up 6.2 y (standard deviation 1.4, range 3.6-8.6). Level of trainee experience was not associated with postoperative outcomes in either the univariate (odds ratio 0.99 [95% confidence interval, 0.98-1.01], P = 0.827) or multivariate analyses (odds ratio 1.00 [95% confidence interval, 0.97-1.02], P = 0.907). CONCLUSIONS: We conclude that podiatry resident level of experience in HVS does not contribute appreciably to postoperative clinical outcomes.

The political ecology of health: perceptions of environment, economy, health and well-being among 'Namgis First Nation.

Informed by Mayer's (Progr. Hum. Geogr 20 (1996) 441) political ecology of disease framework, this paper investigates First Nation's perceptions of the links between environment, economy and health and well-being. A case study of 'Namgis First Nation (Alert Bay, British Columbia, Canada) is used to explore the risks and benefits of salmon aquaculture for British Columbia's First Nations. Analysis of interview data (n = 23) indicates strong links between reduced access to environmental resources, marginal participation in the economy, and declining community health and well being. Results suggest that aquaculture development has further decreased the community's access to environmental resources, thereby restricting those economic, social, and cultural activities that determine good health and well-being for this community.

A revision of Phoreiobothrium (Tetraphyllidea: Onchobothriidae) with descriptions of five new species.

Five new species of Phoreiobothrium (Cestoda: Tetraphyllidea) are described from carcharhiniform sharks collected from a diversity of localities throughout the world. These are Phoreiobothrium perilocrocodilus n. sp. from Negaprion acutidens, Phoreiobothrium anticaporum n. sp. from Negaprion brevirostris, Phoreiobothrium lewinense n. sp. from Sphyrna lewini, Phoreiobothrium robertsoni n. sp. from Carcharhinus brachyurus, and Phoreiobothrium blissorum n. sp. from C. plumbeus, This brings the number of described species of Phoreiobothrium to 17. The new species from the lemon sharks, P. perilocrocodilus n. sp. and P. anticaporum n. sp., both possess more bothridial subloculi than do all species from hammerhead sharks, and fewer subloculi than do all species from sharks of Carcharhinus spp. Phoreiobothrium anticaporum n. sp. is unique among Phoreiobothrium species in that its genital pore is located in the extreme anterior portion of the proglottid. Phoreiobothrium lewinense n. sp. is unique in its possession of a combination of 8-11 subloculi and basal hook prongs that lack internal channels. Phoreiobothrium robertsoni n. sp. possesses 25-29 subloculi, triangular bothridia that flare posteriorly, and hooks that extend well beyond the middle of the bothridia. Phoreiobothrium blissorum n. sp. is most similar to Phoreiobothrium lasium in that it possesses rectangular bothridia with greater than 22 subloculi and long filitriches on its scolex. However, it differs from the latter species in that rather than articulating with one another, the bases of the medial and lateral hooks are widely separated; it also possesses 5-6 (vs.) 7-8 columns of testes. Phoreiobothrium lasium and Phoreiobothrium tiburonis are redescribed. The host associations of P. lasium are reevaluated and a neotype is designated for this species. The mature proglottid of P. tiburonis is described for the first time from voucher material collected from the type host and locality. These data suggest that the proglottid information provided in the original description, which was obtained from detached gravid proglottids, may have come from a tapeworm species other than P. tiburonis. All 7 species treated here in detail were examined with scanning electron microscopy; most were found to exhibit a microthrix pattern similar to that described previously for other members of the genus, e.g., Phoreiobothrium manirei. Bladelike spinitriches were present on the strobila, cephalic peduncle, and proximal bothridial surfaces, but were lacking from the distal bothridial surfaces. These spinitriches varied in length and density among species. Filitriches were present on all of these surfaces, but varied somewhat in length among species. Phoreiobothrium lewinense n. sp. is exceptional in that spinitriches were not seen on the proximal bothridial surfaces. A key to Phoreiobothrium species is provided. This work brings the number of carcharhinid shark species known to host this onchobothriid genus to 6, and the number of sphyrnid species to 5. Like many other onchobothriid tapeworms, species of Phoreiobothrium appear to exhibit oioxenous specificity for their hosts. Given this, and the fact that a total of 9 genera and 46 species of carcharhinid and sphyrnid sharks have yet to be examined for Phoreiobothrium, the diversity of the genus globally is likely to greatly exceed that described to date.

On differential variability of expression ratios: improving statistical inference about gene expression changes from microarray data.

We consider the problem of inferring fold changes in gene expression from cDNA microarray data. Standard procedures focus on the ratio of measured fluorescent intensities at each spot on the microarray, but to do so is to ignore the fact that the variation of such ratios is not constant. Estimates of gene expression changes are derived within a simple hierarchical model that accounts for measurement error and fluctuations in absolute gene expression levels. Significant gene expression changes are identified by deriving the posterior odds of change within a similar model. The methods are tested via simulation and are applied to a panel of Escherichia coli microarrays.

High-density microarray-mediated gene expression profiling of Escherichia coli.

A nearly complete collection of 4,290 Escherichia coli open reading frames was amplified and arrayed in high density on glass slides. To exploit this reagent, conditions for RNA isolation from E. coli cells, cDNA production with attendant fluorescent dye incorporation, DNA-DNA hybridization, and hybrid quantitation have been established. A brief isopropyl-beta-D-thiogalactopyranoside (IPTG) treatment elevated lacZ, lacY, and lacA transcript content about 30-fold; in contrast, most other transcript titers remained unchanged. Distinct RNA expression patterns between E. coli cultures in the exponential and transitional phases of growth were catalogued, as were differences associated with culturing in minimal and rich media. The relative abundance of each transcript was estimated by using hybridization of a genomic DNA-derived, fluorescently labeled probe as a correction factor. This inventory provided a quantitative view of the steady-state level of each mRNA species. Genes the expression of which was detected by this method were enumerated, and results were compared with the current understanding of E. coli physiology.

Effects of hydration on febrile temperature patterns in rabbits.

Patients with fever have a predisposition to experience dehydration, which may alter their thermoregulatory responses to elevated body temperature. In view of the recent discovery of the antipyretic activity of arginine vasopressin (AVP), it is possible that dehydration has a beneficial role during fever. Dehydration may enhance endogenous antipyresis by stimulating AVP release, making aggressive fluid replacement, which may inhibit AVP release, undesirable during fever. This study addressed the effects of manipulation of hydration status on temperature and cardiovascular responses in endotoxin-injected rabbits. Eight unanesthetized chronically instrumented rabbits were exposed to lipopolysaccharide (LPS) while in euhydrated state, after furosemide (5 mg/kg) and 24 hours of water deprivation (dehydrated), after infusion of saline (30 mL/kg) while in euhydrated state (hyperhydrated), and after saline (mL/per overnight body weight loss in grams) while in dehydrated state (rehydrated). Dehydrated rabbits display higher fevers that are biphasic in nature and are accompanied by increased vasoconstriction and duration of mean arterial pressure increases, indicating that activation of antipyretic mechanisms in dehydrated rabbits was not sufficient to reduce body core temperature. In addition, fluid supplementation in euhydrated rabbits did not alter the febrile response; however, a marked decrease in heart rate was noted. Furthermore, fluid supplementation in dehydrated rabbits significantly attenuates the rectal temperature and heart rate response to LPS injection, indicating the possibility that activation of antipyretic mechanisms of AVP in rehydrated rabbits was sufficient to reduce body core temperature. The results suggest that fluid supplementation has a beneficial role in keeping body temperature lower .

RNA expression analysis using a 30 base pair resolution Escherichia coli genome array.

We have developed a high-resolution "genome array" for the study of gene expression and regulation in Escherichia coli. This array contains on average one 25-mer oligonucleotide probe per 30 base pairs over the entire genome, with one every 6 bases for the intergenic regions and every 60 bases for the 4,290 open reading frames (ORFs). Twofold concentration differences can be detected at levels as low as 0.2 messenger RNA (mRNA) copies per cell, and differences can be seen over a dynamic range of three orders of magnitude. In rich medium we detected transcripts for 97% and 87% of the ORFs in stationary and log phases, respectively. We found that 1, 529 transcripts were differentially expressed under these conditions. As expected, genes involved in translation were expressed at higher levels in log phase, whereas many genes known to be involved in the starvation response were expressed at higher levels in stationary phase. Many previously unrecognized growth phase-regulated genes were identified, such as a putative receptor (b0836) and a 30S ribosomal protein subunit (S22), both of which are highly upregulated in stationary phase. Transcription of between 3,000 and 4,000 predicted ORFs was observed from the antisense strand, indicating that most of the genome is transcribed at a detectable level. Examples are also presented for high-resolution array analysis of transcript start and stop sites and RNA secondary structure.

Functional genomics: expression analysis of Escherichia coli growing on minimal and rich media.

DNA arrays of the entire set of Escherichia coli genes were used to measure the genomic expression patterns of cells growing in late logarithmic phase on minimal glucose medium and on Luria broth containing glucose. Ratios of the transcript levels for all 4,290 E. coli protein-encoding genes (cds) were obtained, and analysis of the expression ratio data indicated that the physiological state of the cells under the two growth conditions could be ascertained. The cells in the rich medium grew faster, and expression of the majority of the translation apparatus genes was significantly elevated under this growth condition, consistent with known patterns of growth rate-dependent regulation and increased rate of protein synthesis in rapidly growing cells. The cells grown on minimal medium showed significantly elevated expression of many genes involved in biosynthesis of building blocks, most notably the amino acid biosynthetic pathways. Nearly half of the known RpoS-dependent genes were expressed at significantly higher levels in minimal medium than in rich medium, and rpoS expression was similarly elevated. The role of RpoS regulation in these logarithmic phase cells was suggested by the functions of the RpoS dependent genes that were induced. The hallmark features of E. coli cells growing on glucose minimal medium appeared to be the formation and excretion of acetate, metabolism of the acetate, and protection of the cells from acid stress. A hypothesis invoking RpoS and UspA (universal stress protein, also significantly elevated in minimal glucose medium) as playing a role in coordinating these various aspects and consequences of glucose and acetate metabolism was generated. This experiment demonstrates that genomic expression assays can be applied in a meaningful way to the study of whole-bacterial-cell physiology for the generation of hypotheses and as a guide for more detailed studies of particular genes of interest.

Genome-wide expression profiling in Escherichia coli K-12.

We have established high resolution methods for global monitoring of gene expression in Escherichia coli. Hybridization of radiolabeled cDNA to spot blots on nylon membranes was compared to hybridization of fluorescently-labeled cDNA to glass microarrays for efficiency and reproducibility. A complete set of PCR primers was created for all 4290 annotated open reading frames (ORFs) from the complete genome sequence of E.coli K-12 (MG1655). Glass- and nylon-based arrays of PCR products were prepared and used to assess global changes in gene expression. Full-length coding sequences for array printing were generated by two-step PCR amplification. In this study we measured changes in RNA levels after exposure to heat shock and following treatment with isopropyl-beta-D-thiogalactopyranoside (IPTG). Both radioactive and fluorescence-based methods showed comparable results. Treatment with IPTG resulted in high level induction of the lacZYA and melAB operons. Following heat shock treatment 119 genes were shown to have significantly altered expression levels, including 35 previously uncharacterized ORFs and most genes of the heat shock stimulon. Analysis of spot intensities from hybridization to replicate arrays identified sets of genes with signals consistently above background suggesting that at least 25% of genes were expressed at detectable levels during growth in rich media.

Cultural control of larval mosquito production in a fallow citrus grove used for disposal of secondary-treated sewage effluent.

Larval mosquito production was monitored for 16 months in the furrows of a 13.4-ha citrus grove in east-central Florida used for disposal of secondary-treated sewage effluent. Twenty-one species of mosquito were collected, and the 2 most abundant species were Culex nigripalpus and Aedes vexans. An unplanned removal of all brush and trees from the site during the study resulted in an overall decline in larval production, but species diversity remained the same.