8,875 research outputs found
Analysis of the Changes in the Oxidation of Brain Tissue Cytochrome-c-Oxidase in Traumatic Brain Injury Patients during Hypercapnoea A Broadband NIRS Study
Using broadband near-infrared spectroscopy (NIRS) and cerebral micro-dialysis (MD), we investigated cerebral cellular metabolism and mitochondrial redox states, following hypercapnoea in 6 patients with traumatic brain injury (TBI). In all patients hypercapnoea increased intracranial pressure and cerebral blood flow velocity measured with transcranial Doppler. Despite the likely increase in cerebral oxygen delivery, we did not see an increase in the oxidation status of cytochrome-c-oxidase [oxCCO] in every patient. Analysis of the NIRS data demonstrated two patterns of the changes; Group A (n = 4) showed an increase in [oxCCO] of 0.34(+/-0.34)mu M and Group B (n = 2) a decrease of 0.40(+/- 0.41)mu M. Although no obvious association was seen between the Delta[oxCCO] and the MD, measured changes in lactate and pyruvate concentrations. Further work using model informed data interpretation may be helpful in understanding the multimodal signals acquired in this heterogeneous patient group
The costs and potential savings of a novel telepaediatric service in Queensland
BACKGROUND: There are few cost-minimisation studies in telemedicine. We have compared the actual costs of providing a telepaediatric service to the potential costs if patients had travelled to see the specialist in person. METHODS: In November 2000, we established a novel telepaediatric service for selected regional hospitals in Queensland. Instead of transferring patients to Brisbane, the majority of referrals to specialists in Brisbane were dealt with via videoconference. Since the service began, 1499 consultations have been conducted for a broad range of paediatric sub-specialities including burns, cardiology, child development, dermatology, diabetes, endocrinology, gastroenterology, nephrology, neurology, oncology, orthopaedics, paediatric surgery and psychiatry. RESULTS: During a five year period, the total cost of providing 1499 consultations through the telepaediatric service was A1,553,264; thus, telepaediatric services resulted in a net saving of approximately A$600,000 to the health service provider. CONCLUSION: Telepaediatrics was a cheaper method for the delivery of outpatient services when the workload exceeded 774 consultations. A sensitivity analysis showed that the threshold point was most sensitive to changes related to patient travel costs, coordinator salaries and videoconference equipment costs. The study showed substantial savings for the health department, mainly due to reduced costs associated with patient travel
Nafion Matrix and Ionic Domain Tuning for High-Performance Composite Proton Exchange Membranes
Although proton exchange membranes (PEMs) are widely deployed in an array of commercial applications, limitations linked to their proton conductivity, water retention, and gas permeability still limit ultimate device performance. While ex situ studies have shown additives can enhance membrane stability and mass transport, to date few have demonstrated that these performance enhancements are maintained when tested in commercially relevant electrochemical technologies, such as fuel cells or electrolyzers. Herein, a new multifunctional additive, 2D poly(triazine imide) (PTI), is demonstrated for composite PEMs, which is shown to boost proton conductivity by 37% under optimal high relative humidity (RH) conditions and 67% at low RHs. PTI also enables major improvements (over 55%) in both current and power densities in industrially relevant PEM fuel cells (PEMFCs). Most importantly, in situ and ex situ characterization suggests that the enhanced performance is due to polymer aggregate-PTI clusters that form with increasing 2D character and improved long-range connectivity, while acid-base interactions with pyridinic nitrogen facilitate the critical proton hopping mechanism at all RHs. Hence, this work offers both a new membrane concept with proven benefits for important electrochemical technologies, as well as design principles for future optimization of proton transport and water management within PEMs
Theoretical investigation of measuring cerebral blood flow in the adult human head using bolus Indocyanine Green injection and near-infrared spectroscopy
To investigate the accuracy of measuring cerebral blood flow (CBF) using a bolus injection of Indocyanine Green (ICG) detected by near-infrared spectroscopy in adult human heads, simulations were performed using a two-layered model representing the extracerebral and intracerebral layers. Modeled optical data were converted into tissue ICG concentration using either the one-detector modified Beer-Lambert law (MBLL) method, or the two-detector partial path-length (PPL) method. The CBFs were estimated using deconvolution and blood flow index techniques. Using the MBLL method, the CBFs were significantly underestimated but the PPL method improved their accuracy and robustness, especially when used as relative measures. The dispersion of the arterial input function also affected the CBF estimates. (c) 2007 Optical Society of America
Coconut in the Mekong Delta: An Assessment of Competitivenessand Industry Potential
The numbers surrounding the world coconut industry are substantial – 55,500,000,000 coconuts produced every year from 12,000,000 hectares supporting an industry worth USD 6 billion at wholesale. Yet despite the size and wealth of the industry most coconut growers are among the poorest in their society and over 1 million tonnes of coconut dust are dumped into the environment every year.
In the Mekong Delta, riverbanks shaded with coconut trees are an iconic part of the landscape, but only in the last decade has the local coconut industry taken the first steps to becoming a modern, competitive industry. Much of this recent development has happened in Ben Tre province, at the heart of the industry in the Delta with the greatest concentration of coconut trees and businesses. The Ben Tre authorities and industry leaders are now looking to help the industry mature into an internationally competitive and sustainable coconut industry that maximises the value created for the local community, businesses and coconut farmers.
This study is part of that process and aims to provide evidence of the current state of the global coconut industry and the local industry in Ben Tre and the wider Mekong Delta and to assess specific opportunities for the industry’s future development. The study also identifies several promising commercial opportunities for local coconut businesses and the impacts these could have on the company’s own bottom-line profits as well as the wider industry. It supplements extensive secondary data with insights and evidence gathered through an international benchmarking exercise with leading competitor countries, including the Philippines, Sri Lanka and Thailand as well as the local industry in Ben Tre
Icequake Source Mechanisms for Studying Glacial Sliding
Improving our understanding of glacial sliding is crucial for constraining basal drag in ice dynamics models. We use icequakes, sudden releases of seismic energy as the ice slides over the bed, to provide geophysical observations that can be used to aid understanding of the physics of glacial sliding and constrain ice dynamics models. These icequakes are located at the bed of an alpine glacier in Switzerland and the Rutford Ice Stream, West Antarctica, two extremes of glacial settings and spatial scales. We investigate a number of possible icequake source mechanisms by performing full waveform inversions to constrain the fundamental physics and stress release during an icequake stick-slip event. Results show that double-couple mechanisms best describe the source for the events from both glacial settings and the icequakes originate at or very near the ice-bed interface. We also present an exploratory method for attempting to measure the till shear modulus, if indirect reflected icequake radiation is observed. The results of this study increase our understanding of how icequakes are associated with basal drag while also providing the foundation for a method of remotely measuring bed shear strengt
Operando Electrochemical Atomic Force Microscopy of Solid–Electrolyte Interphase Formation on Graphite Anodes: The Evolution of SEI Morphology and Mechanical Properties
Understanding and ultimately controlling the properties of the solid–electrolyte interphase (SEI) layer at the graphite anode/liquid electrolyte boundary are of great significance for maximizing the performance and lifetime of lithium-ion batteries (LIBs). However, comprehensive in situ monitoring of SEI formation and evolution, alongside measurement of the corresponding mechanical properties, is challenging due to the limitations of the characterization techniques commonly used. This work provides a new insight into SEI formation during the first lithiation and delithiation of graphite battery anodes using operando electrochemical atomic force microscopy (EC-AFM). Highly oriented pyrolytic graphite (HOPG) is investigated first as a model system, exhibiting unique morphological and nanomechanical behavior dependent on the various electrolytes and commercially relevant additives used. Then, to validate these findings with respect to real-world battery electrodes, operando EC-AFM of individual graphite particles like those in commercial systems are studied. Vinylene carbonate (VC) and fluoroethylene carbonate (FEC) are shown to be effective additives to enhance SEI layer stability in 1 M LiPF6/ethylene carbonate/ethyl methyl carbonate (EC/EMC) electrolytes, attributed to their role in improving its structure, density, and mechanical strength. This work therefore presents an unambiguous picture of SEI formation in a real battery environment, contributes a comprehensive insight into SEI formation of electrode materials, and provides a visible understanding of the influence of electrolyte additives on SEI formation
Critical role of the disintegrin metalloprotease ADAM-like Decysin-1 (ADAMDEC1) for intestinal immunity and inflammation
BACKGROUND AND AIMS: ADAM (A Disintegrin And Metalloproteinase) is a family of peptidase proteins, which have diverse roles in tissue homeostasis and immunity. Here, we study ADAM-like Decysin-1 (ADAMDEC1) a unique member of the ADAM family. ADAMDEC1 expression is restricted to the macrophage/dendritic cell populations of the gastrointestinal tract and secondary lymphoid tissue. The biological function of ADAMDEC1 is unknown but it has been hypothesised to play a role in immunity. The identification of reduced ADAMDEC1 expression in Crohn's disease patients has provided evidence of a potential role in bowel inflammation. METHODS: Adamdec1(-/-) mice were exposed to dextran sodium sulphate or infected orally with Citrobacter rodentium or Salmonella typhimurium The clinical response was monitored. RESULTS: The loss of Adamdec1 rendered mice more susceptible to the induction of bacterial and chemical induced colitis, as evidenced by increased neutrophil infiltration, greater IL-6 and IL-1β secretion, more weight loss and increased mortality. In the absence of Adamdec1, greater numbers of Citrobacter rodentium were found in the spleen, suggestive of a breakdown in mucosal immunity which resulted in bacteraemia. CONCLUSION: In summary, Adamdec1 protects the bowel from chemical and bacterial insults, failure of which may predispose to Crohn's disease
Direct fluorescence characterisation of a picosecond seeded optical parametric amplifier
The temporal intensity contrast of high-power lasers based on optical parametric amplification (OPA) can be limited by parametric fluorescence from the non-linear gain stages. Here we present a spectroscopic method for direct measurement of unwanted parametric fluorescence widely applicable from unseeded to fully seeded and saturated OPA operation. Our technique employs simultaneous spectroscopy of fluorescence photons slightly outside the seed bandwidth and strongly attenuated light at the seed central wavelength. To demonstrate its applicability we have characterised the performance of a two-stage picosecond OPA pre-amplifier with 2.8×105 gain, delivering pulses at 1054 nm. We show that fluorescence from a strongly seeded OPA is reduced by ~500× from the undepleted to full pump depletion regimes. We also determine the vacuum fluctuation driven noise term seeding this OPA fluorescence to be 0.7±0.4 photons ps−1 nm−1 bandwidth. The resulting shot-to-shot statistics highlights a 1.5% probability of a five-fold and 0.3% probability of a ten-fold increase of fluorescence above the average value. Finally, we show that OPA fluorescence can be limited to a few-ps pedestal with 3×10−9 temporal intensity contrast 1.3 ps ahead of an intense laser pulse, a level highly attractive for large scale chirped-pulse OPA laser systems
The influence of feeding behaviour and temperature on the capacity of mosquitoes to transmit malaria
Insecticide-treated bed nets reduce malaria transmission by limiting contact between mosquito vectors and human hosts when mosquitoes feed during the night. However, malaria vectors can also feed in the early evening and in the morning when people are not protected. Here, we explored how the timing of blood feeding interacts with environmental temperature to influence the capacity of Anopheles mosquitoes to transmit the human malaria parasite Plasmodium falciparum. In laboratory experiments, we found no effect of biting time itself on the proportion of mosquitoes that became infectious (vector competence) at constant temperature. However, when mosquitoes were maintained under more realistic fluctuating temperatures, there was a significant increase in competence for mosquitoes feeding in the evening (18:00), and a significant reduction in competence for those feeding in the morning (06:00), relative to those feeding at midnight (00:00). These effects appear to be due to thermal sensitivity of malaria parasites during the initial stages of parasite development within the mosquito, and the fact that mosquitoes feeding in the evening experience cooling temperatures during the night, whereas mosquitoes feeding in the morning quickly experience warming temperatures that are inhibitory to parasite establishment. A transmission dynamics model illustrates that such differences in competence could have important implications for malaria prevalence, the extent of transmission that persists in the presence of bed nets, and the epidemiological impact of behavioural resistance. These results indicate that the interaction of temperature and feeding behaviour could be a major ecological determinant of the vectorial capacity of malaria mosquitoes
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