A Comparison of Laser and Microwave Approaches to CW Beamed Energy Launch

One approach to beamed energy propulsion uses a solid heat exchanger to absorb energy from a distant source and transfer it to a working fluid. Systems of this type can be designed using either microwave or laser sources. In general, microwave sources have been expected to be less expensive than lasers for a given power, but to be more limited in range and/or energy density. With the development of high power millimeter-wave sources and low-cost diode laser arrays, both assumptions are open to question. In this paper, we compare current and projected microwave and laser source technologies for a 100-kilogram-class ground-to-orbit launch system and identify key issues affecting the system-level trade between the two approaches

Pressure distribution on a hydrofoil running near the water surface

The effect of the free surface on the pressure distribution on the upper side of a shallow-running hydrofoil is considered from a general point of view. Previous theoretical and experimental work is reviewed in order to compare the range of flow variables for which each treatment of the surface proximity problem is valid. A qualitative theoretical expression for the pressure is developed. This result shows the relative importance of the pertinent parameters and it is shown to agree qualitatively with previous experiments as well as with new pressure measurements made in the Free Surface Water Tunnel. The above considerations reinforce the view generally held in the past, that the methods of potential theory when properly applied to hydrofoils at shallow submergences may be expected to lead to valid and useful results

Acute phase protein levels in dogs with mast cell tumours and sarcomas

<p><b>Context:</b> The acute phase protein response is part of a non-specific and complex host response to inflammation. It occurs shortly after tissue injury and may be induced by a range of different causes, including infectious, inflammatory, neoplastic, traumatic or immunological disease. Although it was conventionally believed that APPs were exclusively hepatocyte derived, there is increasing evidence to support extra-hepatic generation in neoplastic and other disease states. In people, C-reactive protein (CRP) has been shown to be of value in identifying metastatic disease from primary renal tumours as well as showing promise for monitoring rejection of renal transplants. Serum CRP correlates with survival in colorectal cancer and oesophageal squamous cell carcinoma while serum amyloid A (SAA) concentrations correlate with cancer activity, stage and prognosis in gastric tumours. Recent immunohistochemical studies in people with oesophageal carcinoma suggest that tumour tissue may itself elaborate APP with a poorer survival and outcome associated with tumours elaborating higher levels of CRP. A similar association has been seen between alpha-1 acid glycoprotein (AGP) and colorectal tumours and ovarian carcinoma.</p> <p>As yet, studies regarding APP values in neoplastic conditions in dogs are limited, and many are non-specific. In veterinary patients, elevated levels of AGP have been identified in dogs with a range of tumours with localisation to liver and splenic tissue in one study. Another study found higher levels of AGP in dogs with non-specific tumours of grade III-IV based on the WHO Tumour Node Metastasis (TNM) scale and elevated serum AGP has been documented in non-specific tumour-bearing cats. Elevated CRP levels have been documented in both dogs and cats with lymphoma and serum CRP may be used as an indicator of complete remission status in dogs with multicentric lymphoma. Elevated levels of CRP, Haptoglobin (Hp) and SAA have been identified in dogs with mammary tumours, with significant increases over normal in the presence of metastatic disease, primary tumours greater than 5cm in diameter and those with ulceration.</p> <p>In this study we evaluated an APP profile using four APPs (CRP, Hp, SAA and AGP), in dogs with mast cell tumours (MCTs) and sarcomas to assess whether the APP profile would change in reflection of tumour presence; whether the extent of any change would correlate with tumour grade; and whether the changes would differ with tumour type.</p> <p><b>Approach:</b> Patients with naturally occurring MCTs and sarcomas presenting for staging and treatment were included if they met the study criteria. Criteria for inclusion were that the patient was not currently being treated with steroids, did not have a recent history of infectious or inflammatory disease other than the tumour, a definitive histological diagnosis was available and a full staging procedure was completed prior to surgery using standard oncological protocols to identify metastatic disease where present. Following surgical resection each tumour was submitted for full histological evaluation and grading to include assessment of the margins of excision. Cases were only enrolled in the study if blood sampling formed part of the clinical investigation and/or treatment, and where residual blood was available after diagnostic sampling which would otherwise have been disposed of as clinical waste. In brief, the CRP levels were determined by immunoturbidometric assay and Hp by means of haemoglobin binding capacity assay. SAA was measured with a commercial canine ELISA kit (TriDelta Development, Dublin, Ireland) and AGP was measured with a commercial radial immunodiffusion assay (J-Path Inc, Tokyo, Japan).</p> <p><b>Results:</b> All comparisons using continuous data were checked for normality and equality of variances and appropriate statistical tests were employed (student’s t test operationalised as a two-sample Welch’s test for samples of unequal sizes and variances, Mann-Whitney, Chi-square and Fishers exact tests as appropriate). In MCTs, the CRP and AGP were elevated above reference ranges, Hp showed no significant change and SAA dropped relative to the reference range. In sarcoma patients CRP, Hp and AGP were all elevated above reference ranges. None of the tumour grade differences were significant apart from SAA in sarcoma patients where values in grade 2 sarcoma were significantly higher than those in grade 1.</p> <p><b>Interpretation and notes of caution:</b> The numbers in our groups were small which compromises the validity of statistical evaluation so our results must be interpreted with caution. However some interesting relationships have emerged from the initial evaluation which suggests that APP profiles may have potential for screening in patients with neoplastic disease. For patients with MCTs, CRP and AGP levels would be expected to increase, with a concurrent drop in SAA levels. In sarcoma patients CRP, AGP and Hp can all be expected to increase. These initial results need to be evaluated in larger numbers of cases with naturally occurring disease to validate the findings, to assess whether the presence and extent of metastatic disease has a significant effect, and also to confirm whether the values alter after surgical resection of the primary tumour.</p> <p><b>Significance of findings:</b> If there are consistent and specific changes in APP profiles associated with different tumour types in dogs, as is the case with a wide range of cancers in humans, then there may be potential for APP profiles on routine blood samples to be used as indicators of disease, or where monitoring for recurrence. Whether they could also have potential for assessment of the presence of metastatic disease and prognosis as in people is unknown as yet.</p&gt

Forces from highly focused laser beams: modeling, measurement and application to refractive index measurements

The optical forces in optical tweezers can be robustly modeled over a broad range of parameters using generalsed Lorenz-Mie theory. We describe the procedure, and show how the combination of experimental measurement of properties of the trap coupled with computational modeling, can allow unknown parameters of the particle - in this case, the refractive index - to be determined.Comment: 5 pages, 4 figures, presented at 17th AIP Congress, Brisbane, 200

Phosphate applications affect the coumestrol level of medics

Western Australia has a million acres of medics including various cultivars of barrel medic, Medicago truncatula, and strand medic, M. littoralis. Both species contain coumestrol, a chemical thought to have caused delayed conception and reduced twinning rates among grazing ewes in New Zealand. No infertility has been reported among ewes grazing medic pastures in Western Australia, but coumestrol levels in both species have often been high enough to suggest the possibility of oestrogenic responses among sheep grazing them

Fluorides, orthodontics and demineralization: a systematic review

Objectives: To evaluate the effectiveness of fluoride in preventing white spot lesion (WSL) demineralization during orthodontic treatment and compare all modes of fluoride delivery. Data sources: The search strategy for the review was carried out according to the standard Cochrane systematic review methodology. The following databases were searched for RCTs or CCTs: Cochrane Clinical Trials Register, Cochrane Oral Health Group Specialized Trials Register, MEDLINE and EMBASE. Inclusion and exclusion criteria were applied when considering studies to be included. Authors of trials were contacted for further data. Data selection: The primary outcome of the review was the presence or absence of WSL by patient at the end of treatment. Secondary outcomes included any quantitative assessment of enamel mineral loss or lesion depth. Data extraction: Six reviewers independently, in duplicate, extracted data, including an assessment of the methodological quality of each trial. Data synthesis: Fifteen trials provided data for this review, although none fulfilled all the methodological quality assessment criteria. One study found that a daily NaF mouthrinse reduced the severity of demineralization surrounding an orthodontic appliance (lesion depth difference –70.0 µm; 95% CI –118.2 to –21.8 µm). One study found that use of a glass ionomer cement (GIC) for bracket bonding reduced the prevalence of WSL (Peto OR 0.35; 95% CI 0.15–0.84) compared with a composite resin. None of the studies fulfilled all of the methodological quality assessment criteria. Conclusions: There is some evidence that the use of a daily NaF mouthrinse or a GIC for bonding brackets might reduce the occurrence and severity of WSL during orthodontic treatment. More high quality, clinical research is required into the different modes of delivering fluoride to the orthodontic patient

The case for new academic workspaces

Executive summary: This report draws upon the combined efforts of a number of estates professionals, architects, academics, designers, and senior managers involved in the planning of new university buildings for the 21st century. Across these perspectives, all would agree – although perhaps for different reasons - that this planning is difficult and that a number of particular considerations apply in the design of academic workspaces. Despite these difficulties, they will also agree that when this planning goes well, ‘good’ buildings are truly transformational – for both the university as a whole and the people who work and study in them. The value of well-designed buildings goes far beyond their material costs, and endures long after those costs have been forgotten ..

Aharonov-Casher effect in a two dimensional hole gas with spin-orbit interaction

We study the quantum interference effects induced by the Aharonov-Casher phase in a ring structure in a two-dimensional heavy hole (HH) system with spin-orbit interaction realizable in narrow asymmetric quantum wells. The influence of the spin-orbit interaction strength on the transport is investigated analytically. These analytical results allow us to explain the interference effects as a signature of the Aharonov-Casher Berry phases. Unlike previous studies on the electron two-dimensional Rashba systems, we find that the frequency of conductance modulations as a function of the spin-orbit strength is not constant but increases for larger spin-orbit splittings. In the limit of thin channel rings (width smaller than Fermi wavelength), we find that the spin-orbit splitting can be greatly increased due to quantization in the radial direction. We also study the influence of magnetic field considering both limits of small and large Zeeman splittings.Comment: 6 pages, 4 figure