Search

We report the results of radioactivity assays and heat leak calculations for a range of common cryogenic materials, considered for use in the QUEST-DMC superfluid 3 He dark matter detector. The bolometer, instrumented with nanomechanical resonators, will be sensitive to energy deposits from dark matter interactions. Events from radioactive decays and cosmic rays constitute a significant background and must be precisely modelled, using a combination of material screening and Monte Carlo simulations. However, the results presented here are of wider interest for experiments and quantum devices sensitive to minute heat leaks and spurious events, thus we present heat leak per unit mass or surface area for every material studied. This can inform material choices for other experiments, especially if underground operation is considered – where the radiogenic backgrounds will dominate even at shallow depths. [ABSTRACT FROM AUTHOR]

The focus of dark matter searches to date has been on Weakly Interacting Massive Particles (WIMPs) in the GeV/ c 2 -TeV/ c 2 mass range. The direct, indirect and collider searches in this mass range have been extensive but ultimately unsuccessful, providing a strong motivation for widening the search outside this range. Here we describe a new concept for a dark matter experiment, employing superfluid 3 He as a detector for dark matter that is close to the mass of the proton, of order 1 GeV/ c 2 . The QUEST-DMC detector concept is based on quasiparticle detection in a bolometer cell by a nanomechanical resonator. In this paper we develop the energy measurement methodology and detector response model, simulate candidate dark matter signals and expected background interactions, and calculate the sensitivity of such a detector. We project that such a detector can reach sub-eV nuclear recoil energy threshold, opening up new windows on the parameter space of both spin-dependent and spin-independent interactions of light dark matter candidates. [ABSTRACT FROM AUTHOR]

Quantum circuits interact with the environment via several temperature-dependent degrees of freedom. Multiple experiments to-date have shown that most properties of superconducting devices appear to plateau out at T ≈ 50 mK – far above the refrigerator base temperature. This is for example reflected in the thermal state population of qubits, in excess numbers of quasiparticles, and polarisation of surface spins – factors contributing to reduced coherence. We demonstrate how to remove this thermal constraint by operating a circuit immersed in liquid 3He. This allows to efficiently cool the decohering environment of a superconducting resonator, and we see a continuous change in measured physical quantities down to previously unexplored sub-mK temperatures. The 3He acts as a heat sink which increases the energy relaxation rate of the quantum bath coupled to the circuit a thousand times, yet the suppressed bath does not introduce additional circuit losses or noise. Such quantum bath suppression can reduce decoherence in quantum circuits and opens a route for both thermal and coherence management in quantum processors. Removing excess energy (cooling) and reducing noise in superconducting quantum circuits is central to improved coherence. Lucas et al. demonstrate cooling of a superconducting resonator and its noisy environment to sub-mK temperatures by immersion in liquid 3He. [ABSTRACT FROM AUTHOR]

In this paper, we apply the Turán sieve and the simple sieve developed by R. Murty and the first author to study problems in random graph theory. In particular, we obtain upper and lower bounds on the probability of a graph on n vertices having diameter 2 (or diameter 3 in the case of bipartite graphs) with edge probability p where the edges are chosen independently. An interesting feature revealed in these results is that the Turán sieve and the simple sieve "almost completely" complement each other. As a corollary to our result, we note that the probability of a random graph having diameter 2 approaches 1 as n → ∞ for constant edge probability p = 1 / 2 . [ABSTRACT FROM AUTHOR]

Superfluid 3He, with unconventional spin-triplet p-wave pairing, provides a model system for topological superconductors, which have attracted significant interest through potential applications in topologically protected quantum computing. In topological insulators and quantum Hall systems, the surface/edge states, arising from bulk-surface correspondence and the momentum space topology of the band structure, are robust. Here we demonstrate that in topological superfluids and superconductors the surface Andreev bound states, which depend on the momentum space topology of the emergent order parameter, are fragile with respect to the details of surface scattering. We confine superfluid 3He within a cavity of height D comparable to the Cooper pair diameter ξ0. We precisely determine the superfluid transition temperature Tc and the suppression of the superfluid energy gap, for different scattering conditions tuned in situ, and compare to the predictions of quasiclassical theory. We discover that surface magnetic scattering leads to unexpectedly large suppression of Tc, corresponding to an increased density of low energy bound states. Surface states in topological quantum matter are protected by their band structure. Here, on confined superfluid 3He as a model for topological superconductors, the authors report experimental evidence on the fragility of surface Andreev bound states with respect to the details of surface scattering. [ABSTRACT FROM AUTHOR]

Introduction: Repair of complex ventral hernia presents a significant challenge plagued by high morbidity and recurrence. Recent studies have demonstrated significant benefits achievable with preoperative Botulinum Toxin A (BTA) chemical component paralysis to the abdominal wall muscles, facilitating primary closure of complex ventral hernia defects. However, transversus abdominis is known to play an integral role in truncal stability, and its paralysis can result in unwanted physiological changes. This is the first study to report on selective administration of preoperative BTA to internal and external oblique muscles only, thus sparing transversus abdominis from paralysis.Methods: This is a prospective observational study of 46 patients who underwent either selective two-layer or standard three-layer abdominal wall muscle BTA injection prior to elective laparoscopic ventral hernia repair. Serial abdominal CT imaging was performed to compare defect size and length of the lateral abdominal musculature.Results: 46 patients received preoperative BTA injections (23 in each group). A comparison of gains achieved from chemical component paralysis demonstrated no statistically significant difference between the two groups. Fascial closure was achieved in all cases, with no post-operative sequelae of abdominal hypertension. There are no hernia recurrences to date.Conclusion: Preoperative selective muscle chemical component paralysis is an effective technique to counteract the chronic muscle retraction observed in large ventral hernias. Transversus abdominis plays a significant role in truncal and spinal stability, and sparing it from paralysis preserves an important component of abdominal wall physiology and does not detract from the ability to primarily close complex defects. [ABSTRACT FROM AUTHOR]

Recent torsional oscillator measurements on the second layer of $$^4 \hbox {He}$$ adsorbed on graphite have identified an anomalous superfluid response over a coverage range near third-layer promotion, with four distinct coverage regimes. Here, we present details of the superfluid response in the coverage regime immediately below third-layer promotion. A scaling analysis of the inferred superfluid fraction shows the characteristic temperature governing the superfluid response to decrease, approaching zero near the coverage at which simulations predict the second layer to form a conventional incommensurate solid. [ABSTRACT FROM AUTHOR]

Background: Patients may be accompanied to the pain clinic consultation and these accompanying persons are relevant in the communication process. Aims: We sought to characterize if patients were accompanied and by whom to the pain clinic. We also wished to determine the accompanying persons influence on the doctor-patient interaction. This has not been studied previously in this clinical setting. Methods: Local ethics committee approval followed by written informed consent was obtained. Patients attending the pain clinic for the first time and review patients were included ( n = 219). Results: Twenty-one percent of patients ( n = 46) were accompanied. Adult accompanied by spouse 19 (41.3 %) and adult child accompanied by parent 18 (39.1 %) were the most common dyads. The accompanying person's role was most frequently described by doctors as an advocate for the patient 30/46 (65.2 %) [for an adult accompanied by spouse (63.1 %)]. The influence of the main accompanying person on the patient doctor encounter was described as positive [adult accompanied by spouse (78.9 %)] [(adult accompanied by parent (94.4 %)]. Conclusions: Patients are accompanied to the pain clinic with a typically positive influence on doctor patient relationship and communication. Awareness of these issues is important in good communication in the pain clinic. [ABSTRACT FROM AUTHOR]

We describe the design and performance of a series of fast, precise current sensing noise thermometers. The thermometers have been fabricated with a range of resistances from 1.290 $$\Omega $$ down to 0.2 m $$\Omega $$ . This results in either a thermometer that has been optimised for speed, taking advantage of the improvements in superconducting quantum interference device noise and bandwidth, or a thermometer optimised for ultra-low temperature measurement, minimising the system noise temperature. With a single temperature calibration point, we show that noise thermometers can be used for accurate measurements over a wide range of temperatures below 4 K. Comparisons with a melting curve thermometer, a calibrated germanium thermometer and a pulsed platinum nuclear magnetic resonance thermometer are presented. For the 1.290 $$\Omega $$ resistance we measure a 1 % precision in just 100 ms, and have shown this to be independent of temperature. [ABSTRACT FROM AUTHOR]

We review recent experiments in which superfluid $$^3$$ He has been studied under highly controlled confinement in nanofluidic sample chambers. We discuss the experimental challenges and their resolution. These methods open the way to a systematic investigation of the superfluidity of $$^3$$ He films, and the surface and edge excitations of topological superfluids. [ABSTRACT FROM AUTHOR]

Background: This study aimed to retrospectively assess the accuracy of minimal preparation computed tomography (MPCT) in the detection of colorectal cancer (CRC) within the frail and elderly population and to evaluate the relevance of extra-colonic findings (ECF). Methods: Radiology reports, clinical notes and follow-up reports from 207 patients who underwent MPCT to investigate for CRC between 2005 and 2009 were analysed. Patients were scanned following the administration of oral contrast for 48 h, without bowel preparation or colonic insufflation. MPCT results were measured against patient outcomes, with a minimum of 2 years of follow-up. Results: Twelve cases of clinically relevant CRC were confirmed (5.8 %). MPCT correctly identified 11 of these lesions (sensitivity 91.6 %). Thirty-one patients had a possible CRC identified by MPCT, which was not confirmed by further examination (specificity 84.1 %). This results in a positive predictive value of 26.2 % and a negative predictive value of 99.4 %. Five of the patients with colon cancer underwent curative surgery. Sixty-eight clinically relevant ECF were confirmed, including 14 previously undiagnosed extra-colonic malignancies. ECF were considered to account for the presenting complaint in 15.0 % (31/207) of all patients. Conclusions: Minimal preparation computed tomography is an effective and reliable investigation for the exclusion of clinically relevant CRC in this population. It provides clinicians with a valuable and pragmatic alternative to colonoscopy and CT colonography when invasive examination or cathartic bowel preparation will be poorly tolerated and small polyps are of limited significance. MPCT has an advantage over purely luminal imaging in the detection of extra-colonic pathology and appears to have an equally important role in the detection of CRC. [ABSTRACT FROM AUTHOR]

The interplay of bulk and boundary scattering is explored in a regime where quantum size effects modify mesoscopic transport in a degenerate Fermi liquid film of He on a rough surface. We discuss mass transport and the momentum relaxation time of the film in a torsional oscillator geometry within the framework of a quasiclassical theory that includes the experimentally determined power spectrum of the rough surface. The theory explains the anomalous temperature dependence of the relaxation rate observed experimentally. We model further studies on He confined in nanofluidic sample chambers with lithographically defined surface roughness. The improved understanding of surface roughness scattering can be extended to the analogous system of electrons in metals and suggests routes to improve the conductivity of thin metallic films. [ABSTRACT FROM AUTHOR]

Despite an increase in ENT postal questionnaires, the quality of their methodology has been questioned (Ramphul et al. in J Laryngol Otol 119:175-178, ). This retrospective study examined whether quality and utility of such questionnaires published since 2005 has improved. Seventeen consultant postal questionnaires published between 2005 and 2012 were reviewed. Quality of questionnaires was assessed using a 30-point score based on compliance with 15 criteria previously established to evaluate postal questionnaire study-design (Ramphul et al. in J Laryngol Otol 119:175-178, ). Citation rates were used as an indicator of utility. The specific comments made in each citing paper was reviewed providing information on whether questionnaire findings (a) had an impact on clinical practice, (b) were the citing comments positive, (c) negative or (d) non-specific. Recurrent methodological flaws were identified in all questionnaires. The average score assigned was 44 %, versus 32 % previously reported (Ramphul et al. in J Laryngol Otol 119:175-178, ) ( P < 0.01, Student's t test). The low citation rate demonstrates poor utility for postal questionnaires. Citations were general non-specific referencing with no clear indication that questionnaire findings positively impacted clinical practice. In conclusion, although the quality of ENT postal questionnaire has improved since the original study (Ramphul et al. in J Laryngol Otol 119:175-178, ), important recurring methodological flaws still exist. The poor utility, based on low citation rates, also reflects the continued deficiencies in design quality. It is recommended that authors of questionnaire-based research should ensure that guidelines for questionnaire design are adhered in order to improve the validity of findings and hence impact on clinical practice. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the outcome of the management of iatrogenic arterial injuries following knee arthroplasty using a primary endovascular approach. Methods: A detailed review of the management of all iatrogenic arterial injuries to the lower limb following total knee arthroplasty (TKA) referred to the Vascular Surgical Unit of a tertiary referral hospital between July 2005 and December 2007 identified from a prospectively maintained database. Results: Of the seven cases referred over a 30-month period, six patients underwent endovascular treatment with successful limb salvage. All seven injuries were related to the popliteal artery behind the knee: pseudoaneurysm (4), intimal flap occlusion (2) and stenosis (1). One patient underwent above-knee amputation. The presentation and pattern of arterial injuries, potential risk factors for their occurrence, measures to reduce their risk and factors that aid in their early recognition are discussed. Conclusions: An endovascular approach may be considered for the management of these injuries, although it is likely to involve long-term surveillance and may not be appropriate for all cases. Surgeons performing TKA should be aware of the potential risk factors for arterial injury and maintain a high index of suspicion for these infrequent injuries during the post-operative period. [ABSTRACT FROM AUTHOR]

Background: There is increasing interest in the application of recovery principles in mental health services. Aims: We studied the implementation of a programme of intensive case management (ICM) emphasizing recovery principles in a community mental health service in Ireland. Methods: Eighty service attenders with severe and enduring illness characterized by significant ongoing disability were randomized into (1) a group receiving a programme of ICM and (2) a group receiving treatment as usual (TAU). Groups were compared before and after the programme for general psychopathology using the Brief Psychiatric Rating Scale (BPRS) (clinician rated) and How are You? scale (self-rated). The Functional Analysis of Care Environments (FACE) scale provided assessment of multiple functional domains. Results: The overall group (mean age 44.5 ± 13.2 years; 60% male) had mean total Health of the Nation Outcome Scale (HoNOS) scale scores of 10.5 ± 4.6, with problems in social functioning especially prominent (mean social subscale score 5.0 ± 2.7). The ICM group were younger ( p < 0.01) with higher baseline scores on the HoNOS social subscale and BPRS ( p < 0.05). An analysis of covariance, controlling for these baseline differences, indicated greater improvement in BPRS scores ( p = 0.001), How are You? scores ( p = 0.02) and FACE domains for cognition, symptoms and interpersonal relationships (all p < 0.001) in the ICM group. The ICM group underwent greater changes in structured daily activities that were linked to improved BPRS scores ( p = 0.01). Conclusions: A programme of ICM emphasizing recovery principles resulted in significant improvement across psychopathological and functional domains. Improvements were linked to enhanced engagement with structured daily activities. Recovery-oriented practices can be integrated into existing mental health services and provided alongside traditional models of care. [ABSTRACT FROM AUTHOR]

Spontaneous bacterial peritonitis (SBP) is a severe complication of liver disease. A significant proportion of patients have culture-negative ascites, despite having similar signs, symptoms and mortality to those with SBP. Therefore, empirical antibiotic treatment for infection is often started without knowledge of the causative organisms. Here, we investigated the potential of molecular techniques to provide rapid and accurate characterisation of the bacteria present in ascitic fluid. Ascites samples were obtained from 29 cirrhotic patients undergoing clinically indicated therapeutic paracentesis. Bacterial content was determined by terminal restriction fragment length polymorphism (T-RFLP) analysis, quantitative polymerase chain reaction (PCR) and 16S ribosomal clone sequence analysis. Bacterial signal was detected in all samples, compared to three out of ten using standard methods. Bacterial loads ranged from 5.5 × 102 to 5.4 × 107 cfu/ml, with a mean value of 1.9 × 106 cfu/ml (standard deviation ± 9.6 × 106 cfu/ml). In all but one instance, bacterial species identified by culture were also confirmed by molecular analyses. Preliminary data presented here suggests that culture-independent, molecular analyses could provide rapid characterisation of the bacterial content of ascites fluid, providing a basis for the investigation of SBP development and allowing early and targeted antibiotic intervention. [ABSTRACT FROM AUTHOR]

The present study has examined the relationship of groundwater arsenic (As) levels in alluvial aquifers with topographic elevation, slope, and groundwater level on a large basinal-scale using high-resolution (90 m × 90 m) Shuttle Radar Topography Mission (SRTM) digital elevation model and water-table data in Bangladesh. Results show that high As (>50 μg/l) tubewells are located in low-lying areas, where mean surface elevation is approximately 10 m. Similarly, high As concentrations are found within extremely low slopes (<0.7°) in the country. Groundwater elevation (weekly measured by Bangladesh Water Development Board) was mapped using water-table data from 950 shallow (depth <100 m) piezometers distributed over the entire country. The minimum, maximum and mean groundwater elevation maps for 2003 were generated using Universal Kriging interpolation method. High As tubewells are located mainly in the Ganges--Brahmaputra--Meghna delta, Sylhet Trough, and recent floodplains, where groundwater elevation in shallow aquifers is low with a mean value of 4.5 m above the Public Works Datum (PWD) level. Extremely low groundwater gradients (0.01--0.001 m/km) within the GBM delta complex hinder groundwater flow and cause slow flushing of aquifers. Low elevation and gentle slope favor accumulation of finer sediments, As-carrying iron-oxyhydroxide minerals, and abundant organic matter within floodplains and alluvial deposits. At low horizontal hydraulic gradients and under reducing conditions, As is released in groundwater by microbial activity, causing widespread contamination in the low-lying deltaic and floodplain areas, where As is being recycled with time due to complex biogeochemical processes. [ABSTRACT FROM AUTHOR]

Lifestyle management is a challenging undertaking necessitating the adoption of patient-centered techniques and specialized resource materials. These techniques and resources are described in the form of 10 tips for lifestyle management. The areas covered include assessment, behavioral goal setting, monitoring of behavioral performance and progress, and follow-up, including the involvement of multiple disciplines. Several examples and basic resources are described or provided in an effort to facilitate the adoption of the approaches discussed. [ABSTRACT FROM AUTHOR]

Osteoporosis affects both the organic and mineral phases of bone resulting in a decrease in resistance to fracture. Dual x-ray absorptiometry (DEXA) scans are used for diagnosing osteoporosis, which is conventionally characterised by a decrease in mineral density. Unfortunately, some patients who suffer osteoporotic fractures have normal bone density, because both the organic and the mineral phase are affected. However, there are currently no methods of evaluating the health of the organic phase. Patients undergoing treatment for osteoporosis have reported hardening of their fingernails. As the properties of nail and bone may be linked in a comparable, measurable way, this work used both mechanical (nano-indentation) and chemical (Raman spectroscopy) methods to evaluate differences between fingernails sourced from osteoporotic and non-osteoporotic patients. The difference in mean modulus between the nails sourced from the groups was 1.1 GPa. The disulphide bond content of fingernail samples from each group was measured by Raman spectroscopy and disulphide bond content of fingernail was found to be significantly lower in the osteoporotic group. It can be concluded that a relationship between the mechanical and chemical properties of nail and bone may exist in a measurable way. This work has suggested that changes in the organic phase of bone are reflected in similar proteins, such as keratin, from which fingernails are composed. Collagen and keratin are two distinct structural proteins, but they share the need for protein sulphation and disulphide bond formation, via cysteine, for their structural integrity. A disorder of either process should lead to disordered collagen and keratin synthesis. [ABSTRACT FROM AUTHOR]

Dual X-ray absorptiometry (DEXA) is the current gold standard for the diagnosis of osteoporosis. However, patients can suffer osteoporotic fractures despite normal bone mineral density, partly because of unmeasured influences of both the protein and mineral phases of bone that are affected in osteoporosis. There is currently no clinically applicable method of evaluating the health of the protein phase. The proteins in human nail (keratin) and bone (collagen) require sulphation and disulphide bond (S–S) formation for structural integrity and disorders of either sulphur metabolism or cystathione beta-synthase can lead to structural abnormalities in these tissues. Raman protein spectra provide a method of non-invasive measurement of the degree of sulphation of structurally related proteins that may be indicative of bone health. Raman spectroscopy was used to evaluate the disulphide (S–S) content of fingernails. The nail samples came from from 169 women (84 pre- and 85 post-menopausal), of which 39 had a history of osteoporotic fracture. BMD was measured by DXA at the spine. Analyses included parametric and non-parametric tests, dependent on the distribution of the test variable. Mean disulphide content of the nail reduced with age and was slightly higher in pre-, compared to post-menopausal women (P = 0.187). Significantly lower disulphide content was observed in nails obtained from subjects with a history of fracture (P = 0.025). When either disulphide content or BMD was used as a predictor, the odds ratio of these two measures were found to be comparable predictors for fracture status. This suggests that measurements of change in the protein phase of structural proteins such as keratin in the human nail may be correlated with clinically relevant changes in bone proteins that are important in fracture risk. [ABSTRACT FROM AUTHOR]

Two experiments are reported in which the mechanisms underlying retrieval-induced forgetting for complex prose materials were investigated, using the independent probe technique pioneered by Anderson and Spellman (1995). These experiments provide additional empirical evidence in support of an inhibitory account of memory. Specifically, evidence emerged not only for the inhibition of nonpracticed items from practiced sets (i.e., first-order effects), but also for the inhibition of items from nonpracticed sets that were semantically related to practiced items in practiced sets (i.e., cross-category effects) and for items from nonpracticed sets that were semantically related to nonpracticed items in practiced sets (ie., second-order effects). These findings are considered in terms of Anderson and Spellman's model of inhibitory processing. We also outline an alternative inhibitory interpretation. Specifically, we consider how inhibition may function as a way of controlling the spread of activation and what implications this may have for the flexibility and adaptiveness of memory. [ABSTRACT FROM AUTHOR]

Forty-four male and female subjects with no history of falling and whose ages ranged from 10 to 68 years participated in a series of experiments to assess movement at the joints during gait while walking in a straight line, in pivot turns and in turns of 0.33 and 0.66 m diameter. Acceleration at the joints in the forward and side-to-side direction was measured by dual-axis accelerometers placed at the ankles, knees, hips, shoulders, and on the head. Eye movement was assessed from electrodes placed on the sides of the eyes. The results of the experiments showed that for people whose age was above 40 years, significant increases in the forward-back and side-to-side movements occurred at all joints and progressively increased with age. By age 60, adverse movement of the joints as much as quadrupled in many subjects when compared to people whose age was 20-30 years. The increase in joint acceleration occurred equally in the front-back and side-to-side planes. The mechanism of the increased joint movement may be due to tendon laxness, peripheral neuropathy or loss of central control of gait due to age. Accelerometry may be a much more sensitive technique to analyze abnormalities in gait than standard video or observational gait analysis. Results are given as mean (SD) unless otherwise stated. [ABSTRACT FROM AUTHOR]

Polymorphisms among Mediterranean basin Pistacia species and accessions within species were assessed by random amplified polymorphic DNA (RAPD) and amplified fragment length polymorphism (AFLP) analyses. Twenty-eight Pistacia accessions representing six species from geographically diverse locations in the Mediterranean area were analyzed. With RAPD, a total of 259 DNA fragments were amplified by 27 pre-selected primers, 254 were polymorphic fragments. AFLP analysis with 15 primer sets, produced 954 (93%) polymorphic bands out of a total of 1026. A Mantel test revealed an extremely high correlation (r=0.99) between similarity matrices generated from RAPD and AFLP data sets, indicating that similar results were obtained by the two techniques. Dendrograms constructed from the similarity matrices showed that Pistacia species could be clustered into two groups, one group containing all the #E5/E5#. lentiscus and the second group containing all other accessions. The latter group was divided into two subgroups, one consisting of #E5/E5#. palaestina and #E5/E5#. terebinthus; the other consisting of #E5/E5#. atlantica, #E5/E5#. khinjuk and #E5/E5#. vera. P. vera and P. khinjuk were highly similar, as were P. palaestina and P. terebinthus. [ABSTRACT FROM AUTHOR]

Interleukin-12 (IL-12) is an important regulatory cytokine in infection and immunity. Administration of IL-12 may reduce complications of severe malaria in rodents. Polymorphisms in IL12B, the gene encoding the IL-12 p40 subunit, influence the secretion of IL-12 and susceptibility to Type I diabetes. We therefore investigated whether IL12B polymorphisms may affect the outcome of severe malaria. Homozygosity for a polymorphism in the IL12B promoter was associated with increased mortality in Tanzanian children having cerebral malaria but not in Kenyan children with severe malaria. Furthermore, homozygotes for the IL12B promotor polymorphism had decreased production of nitric oxide, which is in part regulated by IL-12 activity. These studies suggest that IL12B polymorphisms, via regulation of IL-12 production, may influence the outcome of malaria infection in at least one African population. [ABSTRACT FROM AUTHOR]

We report on the design of a torsion pendulum that can resolve the mass loading from 5× 10 17 3He atoms (equivalent to a 1000Å film) with a 0.1% resolution. The oscillator is fabricated from coin silver alloy, and the working surfaces are two highly polished coin silver discs, each with well-characterized surface roughness, that are diffusion welded together using a copper gasket. We report on the cell's temperature dependent background. The cell will be used to examine the evolution of the superfluid density and transition temperature as a function of film thickness as well as the normal fluid behavior. [ABSTRACT FROM AUTHOR]

NMR free precession signals from a slab of normal 3He of thickness comparable to the superfluid coherence length have been observed using a SQUID NMR spectrometer at a frequency of 880 kHz. This spectrometer is based on a SQUID with Additional Positive Feedback, directly coupled to a low noise room temperature amplifier, and operated in flux locked loop mode using the direct offset integration technique, with a bandwidth of several MHz. The sensitivity is such that the signal from a 100 nm slab on a 1 cm 2 surface, corresponding to 2× 1017 spins, is clearly resolved. [ABSTRACT FROM AUTHOR]

Inner ear hair cells exhibit many pathologies following exposure to intense sound, and the hair bundle is a major site of damage. This paper measures in vitro hair bundle motion on chick cochlear hair cells after intense in vitro and in vivo stimulation to explore the nature of hair bundle injury. Hair bundle stiffness, as well as relative and asymmetric motion of individual stereocilia, is controlled largely by the extracellular tip links, and a change in hair bundle motion was used to assess tip-link destruction following overstimulation. Intense in vitro stimulation caused a loss in stiffness that fully recovered within 10 min post-exposure. Relative and asymmetric stereocilia motion, however, were unchanged following the exposure, implying that tip links remained intact while the core or rootlet of the stereocilia were damaged and subsequently repaired. Intense and prolonged in vivo sound exposures produced stereocilia movements, measured in vitro, that were indicative of damage to stereocilia and tip links. Finally, the relative susceptibility of hair bundles to overstimulation was addressed by comparing stiffness loss with morphological features in the hair bundles. The loss of stiffness significantly increased as the amount of curvature in the hair bundle contour increased. [ABSTRACT FROM AUTHOR]

Emerging evidence suggests taurolidine reduces the risk of repeated episodes of catheter related blood stream infections (CRBSI) in a subgroup of patients receiving home parenteral nutrition (HPN). We defined 3 indications where taurolidine could be considered and retrospectively analysed data from patients who were treated over a 10 year period to examine the validity of these criteria. Twenty-two patients were identified from a total HPN population of 81, representing 33.2 years of experience. The overall CRBSI rate pre- and post-taurolidine usage was reduced from 5.71 to 0.99 infections per 1000 patient parenteral nutrition days (P-value <0.0001), with reductions identified in each smaller subgroup, confirming previous reports of a significant reduction in infections when taurolidine is used as secondary prophylaxis and providing initial data suggesting the benefit of its use as primary prophylaxis. [ABSTRACT FROM AUTHOR]

We report measurements on solid3 He droplets embedded in a solid4 He matrix. A feature of our experiments is that the mixture crystals, of 1%3 He concentration, are grown under constant pressure conditions to minimise the formation of defects. Upon cooling the mixture isotopic phase separation is clearly observed in both pressure and NMR data. At a pressure of 36 bar the3 He separates as solid droplets. NMR measurements on these droplets indicate values of T1 and T2 similar to those in bulk solid3 He at the same pressure in the temperature-independent régime. Measurements of the bounded diffusion in the droplets indicate a spin diffusion coefficient similar to that in bulk solid3 He at the same pressure. These measurements also show the size of the droplets to be a few microns. [ABSTRACT FROM AUTHOR]

We discuss the use of SQUID NMR for the study of systems of low spin density. The sample is located inside a coil which forms part of a series tuned resonant circuit attached to the input coil of a SQUID. Such a scheme was first discussed by Freeman et al.1 We have studied the pulsed NMR response at 1 MHz of a3 He film adsorbed on the surface of closely packed Mylar sheets. In this case a monolayer corresponds to a spin density a factor of order 104 smaller than that of bulk liquid and a factor of order 102 smaller than with a Grafoil substrate. For our particular SQUID and input coil the calculated noise temperature is 60 mK, significantly better than that so far achieved with a cooled semiconductor preamplifier. We evaluate the present and potential performance of the spectrometer, some of the practicalities involved in its implementation, and discuss the minimum number of detectable spins. [ABSTRACT FROM AUTHOR]

We report on experiments in which we have used a DC SQUID with additional positive feedback (APF) in a broadband pulsed NMR spectrometer, of bandwidth 3.4 MHz, to observe directly the free precession of nuclear spins in bulk metallic samples. The sample is located inside a superconducting receiver coil, which forms a flux transformer with the input coil of the SQUID. The broadband response of the flux transformer, combined with the relatively large bandwidth of the APF SQUID when operated in flux-locked-loop mode, results in a short recovery time. This enables the study of solid-state samples with a short spin-spin relaxation time at frequencies below 1MHz, appropriate at millikelvin temperatures. A further advantage of this scheme is that the NMR frequency can be varied without changes in the detection electronics being necessary. The sensitivity of the DC SQUID detection system, compared with conventional NMR, allows the study of small single crystal samples. The decay of eddy currents following the transmitter pulse is governed by sample size, geometry and resistivity. Typical decay times of less than 10 us are expected on 0.5 mm diameter cylindrical samples. We discuss progress on experiments with aluminium wires at a temperature of 20 mK. [ABSTRACT FROM AUTHOR]

We analyse recent observations, using a torsional oscillator, of the superfluid transition of a fluid4 He bilayer, within the framework of a modified dynamic theory of the Kosterlitz-Thouless transition. A parametric plot of the real and imaginary parts of the complex superfluid density, determined from the measured period shift and dissipation, achieves a high degree of collapse of the experimental data at different coverages onto a ‘universal’ curve. This is compared with the result of the recent theory. [ABSTRACT FROM AUTHOR]

A two dimensional system of strongly correlated fermions can be realised by a fluid monolayer of3 He adsorbed on an atomically flat surface. We report extensive measurements of the heat capacity, c, of3 He adsorbed on graphite plated with two layers of hydrogen deuteride (HD) over a closely spaced grid of coverages in the temperature range l-80mK. The quasiparticle effective mass ratio, inferred from the linear temperature coefficient of the heat capacity, increases from near unity at low densities and appears to diverge approaching localisation. The maximum value of m*/m we are able to unambiguously extract from the data is 13 at a density 5 nm−2. At this density c/T is temperature independent only below 5mK. The behaviour of m*/m and F, inferred from magnetization data, are consistent with the model of almost-localised fermions. We can track the evolution of strong finite temperature deviations from Fermi liquid behaviour as the density of the film and hence m*/m are increased. At sufficiently low temperature this correction is of T2 form going over to a large TlnT deviation for T > 0.05 TF *, as predicted for 2D spin fluctuations. Thus in this system ‘non-Fermi liquid’ behaviour extends to very low temperatures in the strongly correlated, large m */m, limit. [ABSTRACT FROM AUTHOR]

Nuclear spin exchange in the low density two dimensional quantum solid formed by3 He adsorbed on graphite plated by a bilayer of HD has been studied by heat capacity and magnetization measurements. The low densities result in a frustrated magnet with significantly larger effective exchange constants than observed in the antiferromagnetic second layer of3 He on bare graphite. Promotion to a fluid overlayer occurs at 6.8 nm−2. A ferromagnetic anomaly is observed in magnetization measurements at 10 nm−2 with an effective exchange constant of 1.0 mK, about half the value observed at the corresponding anomaly on bare graphite. [ABSTRACT FROM AUTHOR]

Simulation of deposit growth on a two-dimensional substrate was studied based on a new model that tracks individual cubic particles as they form a deposit structure. The present model is an extension of the classical ballistic deposition model. Effects of three different parameters were studied. These include an attraction parameter that is a measure of the particle to particle attractions, an interaction length within which the particles are assumed to influence and be influenced by surrounding particles, and allowed sticking positions (face-face, edge-edge and corner-corner) that favor particular growth directions. Structures with widely varying properties were obtained using this model. The three parameters were found to have considerable effect on the structure including indications of morphological phase transformations. A new property of the system (saturated roughness/deposit growth rate) was identified that can classify the different types of growth into a single type. [ABSTRACT FROM AUTHOR]

Two sugarbeet ( Beta vulgaris L.) genotypes, REL-1 and REL-2, were used to measure the level of somatic embryo and shoot production from hormone-autonomous callus plated under varied nutrient medium combinations of abscisic acid with the growth regulators 6-benzyladenine, 1-naphthaleneacetic acid, or 2,4-dichlorophenoxyacetic acid, with eight sole nitrogen sources, or with different sucrose concentrations. Clone REL-2 produced embryos up to 35-fold more frequently than clone REL-1. Inclusion of abscisic acid at some concentrations consistently improved embryo production in all experiments and was observed to stimulate shoot production. At some concentrations, 1-naphthaleneacetic acid as well as urea and glutamine stimulated greater embryo production over the control, but only for REL-1, for which there was greater room for improvement. Three and five percent sucrose were superior to 1, 7, and 9%. Higher initial 6-benzyladenine concentration [in the range 0, 0.1−1.0 mg/L (0.44−4.44 µ M)] was associated with lower embryo production but greater shoot regeneration for both clones. REL-2 was significantly better than REL-1 in shoot regeneration. The range of embryo production was more than 35-fold between genotypes, whereas the range of physiological effects was no greater than 10-fold. REL-2 has been released to sugarbeet researchers because of its superior embryogenic and shoot regeneration abilities for application in biotechnology. [ABSTRACT FROM AUTHOR]

Somatic hybrids between the zinc hyperaccumulator Thlaspi caerulescens and Brassica napus were produced by electrofusion of protoplasts isolated from each species. Optimization of electrofusion parameters yielded interspecies heteroplasmic fusion rates of up to 13%. Hybrids were selected by screening the growing calli for Zn tolerance. In addition, a second novel selection technique was developed based on the observation that a high proportion of hybrid microcalli grown in liquid media did not adhere to the wall of the culture vessel, while microcalli derived from parental cells did. Seventeen from a total of 64 regenerated plants were conclusively verified as hybrids by AFLP DNA analysis. The hybrid plants were grown in soil for up to 4 months, and at least five flowered. Several of these hybrids survived when grown on high-zinc media.These hybridsaccumulated levels of zinc and cadmium that would have been toxic for B. napus. The data indicate that transfer of the trait for metal hyperaccumulation in plants is possible through somatic hybridization. [ABSTRACT FROM AUTHOR]

The use of swine for teaching purposes in medicine and surgery has largely increased in recent years. Detailed knowledge of the porcine anatomy and physiology is a prerequisite for proper use of pigs as a teaching or an experimental model in interventional radiology. A systematic study of the radiological anatomy was undertaken in more than 100 female pigs aged 6-8 weeks. All studies were performed under general anesthesia in a single session. Animals were sacrificed at the end of the study. Selective angiographies were systematically obtained in all anatomical territories. In other animals CT and MRI examinations were performed and were correlated to anatomical sections and acrylic casts of the vascular structures. Endoscopical examinations of the upper gastrointestinal tract, including retrograde opacification of the biliary and pancreatic ducts, were added in selected animals. The main angiographic aspects of the brain, head and neck, thorax, abdomen, and pelvis were recorded. Similarities and differences in comparison with human anatomy are stressed. Potential applications in interventional radiology are indicated. [ABSTRACT FROM AUTHOR]

Post-ischemic reperfusion impairment, ('no-reflow phenomenon'), was studied in rats subjected to 8-30 minutes of global brain ischemia. During ischemia, rapid and complete loss of cerebral blood flow, EEG andP-high energy phosphates (ATP/PCr) was observed. Brain intravascular perfusion defects were examined by injecting carbon black intravenously in a group of rats with stable cardiopulmonary function and in another group subjected to rapid thoracotomy and intraarterial infusion of the carbon marker. Results indicate that global brain ischemic or non-ischemic control rats given intraarterial carbon black after thoracotomy had varying degrees of vessel filling defects in brain resulting in 'pale tissue areas' suggestive of impaired perfusion (no-reflow). All rats given carbon black intravenously whether global brain ischemic or not, showed normal cerebrovascular filling of the carbon black and absence of 'pale tissue areas'. In addition, post-ischemic cerebral reperfusion following 8-30 minutes global brain ischemia can reverse neuroelectric, energy metabolite and cerebral blood flow loss in rats whose cardiopulmonary function is not compromised. These findings indicate that the 'no-reflow phenomenon' is an agonal or post-mortem artifact observed in the presence of cardiopulmonary failure. [ABSTRACT FROM AUTHOR]

The ototoxicity of kanamycin was investigated in mice treated with the drug either from 6 to 9, 10 to 13, or 15 to 18 days of age. The results showed extensive damage to the outer-hair-cell (OHC) receptors of the cochlea in the 10-13-day group; some less severe damage to the OHC was found in the 6-9-day group, and little damage was observed in the 15-18 day group. The present finding is consistent with the view that the mouse cochlea is most vulnerable to the ototoxic effect of kanamycin during the period of its rapid development, i.e., between 10 and 13 days of age. [ABSTRACT FROM AUTHOR]

We report preliminary results of the first heat capacity measurements on atomically layered3 He –4 He mixture films adsorbed on the surface of graphite. The4 He film consists of two solid and two superfluid atomic layers. The heat capacity has been investigated over the range 1 – 70mK as a function of the surface density of3 He atoms added to the film. At coveragesn3 < 4nm−2 , the3He forms a uniform two dimensional Fermi system. The coverage dependence of the linear coefficient of the heat capacity, γ, allows a determination of the hydrodynamic effective mass and $$F_1^s $$ . At higher coverages a step-like increase in γ is observed, interpreted as the formation of a second two dimensional Fermi system. [ABSTRACT FROM AUTHOR]

We report experiments in which we have used DC SQUIDs in pulsed NMR spectrometers to observe directly the free precession of nuclear spins. A broadband spectrometer, which operates in flux-locked loop mode with a bandwidth of 3.4 MHz using a SQUID with additional positive feedback and an untuned superconducting input circuit, has been used to observe NMR signals from platinum powder at frequencies of 38, 65, 85, 240 and 513 kHz. The performance is compared with a second system in which a DC SQUID is operated open loop as a small signal rf amplifier with a series tank input circuit tuned at 1 MHz. [ABSTRACT FROM AUTHOR]