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Evidence has accumulated over the past twenty years to suggest that the deep-sea environment is not as constant as was at one time thought, but exhibits temporal variations related to the seasonally in the overlying surface waters. Recent results from deep-moored sediment traps suggest that this coupling is mediated through the sedimentation of organic material, while observations in the Porcupine Seabight indicate that in this region, at least, there is a major and rapid seasonal deposition of aggregated phytodetritus to the sea-floor at slope and abyssal depths.
This paper summarises the results of the Porcupine Seabight studies over the past five years or so, using time-lapse sea-bed photography and microscopic, microbiological and chemical analyses of samples of phytodetritus and of the underlying sediment. The data are to some extent equivocal, but they suggest that the seasonal deposition is a regular and dramatic phenomenon and that the material undergoes relatively little degradation during its passage through the water column. The mechanisms leading to the aggregation of the phytodetritus have not been identified, and it is not yet known whether the phenomenon is geographically widespread nor whether it is of significance to the deep-living mid-water and benthic communities.
When two magnetic films are separated by a nonmagnetic film, pinholes in the nonmagnetic film can allow direct contact and, thereby, direct magnetic exchange coupling between the two magnetic films. We have studied this coupling by having one of the magnetic films pinned and leaving the other free to switch at low field. The pinning is accomplished with test structures based on exchange bias and synthetic antiferromagnetic layers. Since the pinning strength increases sharply at low temperatures but orange-peel coupling does not, low-temperature (77 K) measurements appear to identify whether an observed coupling arises primarily from magnetic coupling through pinholes or primarily from orange-peel roughness. Our measurements appear to indicate that the observed coupling arises primarily from magnetic coupling through pinholes for Cu films less than 2.1 nm thick and for Al2O3films less than 0.6 nm thick but primarily from roughness-induced (orange-peel) magnetostatic coupling for larger thicknesses.
Two complementary techniques are used to study the electrical transport properties related to the use of diamonds as materials for ionizing radiation detectors. Transient photoconductivity using soft x-rays is used to probe the first few microns of the material, while ionizing particle-excited conductivity is used to probe the entire bulk of the material (1 millimeter). Both techniques measure the mean drift distance of free carriers, or the collection distance d. In addition, transient photoconductivity is able to extract the lifetimes and mobilities of the excited carriers. The collection distance measured by the two methods are in agreement, suggesting the material is homogeneous. At an applied field of 10 kV/cm, d is 25 to 30 microns, and, up to a field of 25 kV/cm, d has not saturated. The lifetime varies between 100 and 600 ps, and the mobility varies between 1000 and 4000 cm2/V-s, the range due to natural variations from sample to sample. The primary defects limiting the lifetime are believed to be nitrogen impurities and dislocations.
The electrical properties associated with carrier mobility, μ, and lifetime, τ, have been investigated for the chemical vapor deposited (CVD) diamond films using charged particle-induced conductivity and time resolved transient photo-induced conductivity. The collection distance, d, the average distance which electron and hole depart when driven by an applied electric field E, was measured by both methods. The collection distance is related to the carrier mobility and lifetime by d = μEτ Our measurements show that the collection distance increases linearly with sample thickness for CVD diamond films. The collection distance at the growth side of the CVD diamond film is comparable to that of single crystal natural type IIa diamond; at the substrate side of the film, the collection distance is near zero. No saturation of the collection distance is observed for film thickness up to 500 microns.
Plasma treatment and deposition techniques have been used to facilitate the covalent attachment of DNA to polymer surfaces. The variety of surface functional groups that can be created by plasma techniques enables different chemical conjugation routes to be explored. For example, a phosphodiester linkage can be used for surfaces with hydroxyl groups. Likewise, a carboxyamide linkage can be used for surfaces with carboxyl or amine groups. The primary application of the engineered materials has been the hybridization-based separation of multiplexed DNA sequencing products. Traditionally, sequencing reactions are performed individually on single templates. Multiplex sequencing offers reagent and time savings by permitting multiple sequencing reactions on single or multiple templates. The method developed uses recoverable DNA sequencing primers with additional “capture sequences” attached to the 5' end. The capture sequences are designed to be complementary to “binding sequences” covalently attached to the plasma-treated polymer supports. When a solution of the extended recoverable primers is exposed to a polymer support, primers with complementary capture sequences hybridize to the immobilized binding sequences. Contacting a multiplexed sample with a series of solid supports (each having a different binding sequence) selectively removes each set of sequencing products from the mixture. Washing each solid support, followed by releasing the hybridized DNA, results in isolated and purified sequencing products that are amenable to analysis by gel or capillary electrophoresis.
Although pneumonia is a leading cause of death from infectious disease worldwide, comprehensive information about its causes and incidence in low- and middle-income countries is lacking. Active surveillance of hospitalized patients with pneumonia is ongoing in Thailand. Consenting patients are tested for seven bacterial and 14 viral respiratory pathogens by PCR and viral culture on nasopharyngeal swab specimens, serology on acute/convalescent sera, sputum smears and antigen detection tests on urine. Between September 2003 and December 2005, there were 1730 episodes of radiographically confirmed pneumonia (34·6% in children aged <5 years); 66 patients (3·8%) died. A recognized pathogen was identified in 42·5% of episodes. Respiratory syncytial virus (RSV) infection was associated with 16·7% of all pneumonias, 41·2% in children. The viral pathogen with the highest incidence in children aged <5 years was RSV (417·1/100 000 per year) and in persons aged ⩾50 years, influenza virus A (38·8/100 000 per year). These data can help guide health policy towards effective prevention strategies.
An investigation of the survival rate of bacteria after drying in vacuo by the ' spin–freeze' method showed that one of the most important factors was the fluid in which the bacteria were suspended. Broth or nutrient gelatin gave a moderate survival rate, but in various other protein solutions, even though there might be a fair survival immediately after drying, a large fall occurred in the viable count after storage. The addition of glucose to the suspending fluid in concentrations of between 5 and 10% greatly increased the survival rate both immediately and after storage. Some experiments showed that, without added glucose, the longer the drying process was continued the lower was the survival rate, and it is thought that glucose acts by automatically retaining a small amount of water which is necessary for survival. Lactose appears to produce the same effect.
It is shown that the highest death-rate generally occurs during the early stages of drying, the further drop after 24 hr. being small if glucose is used in the suspending fluid. Very young cultures (4½–6 hr.) seem to be far more sensitive to drying than older ones (18–24 hr.). The bacteria that survive drying are not more resistant to subsequent drying.
Most of these results have been obtained with one strain of paracolon bacillus, but a limited number of other experiments show that the same principles hold good for other organisms such as Salmonella typhi-murium, staphylococci, streptococci, Neisseria gonorrhoeae and Vibrio cholerae. In the case of the last two species the percentage survival is much lower than with the others, but survivals up to 1% have been obtained after storage for from 1 to 3 years.
A point source outbreak of haemorrhagic colitis due to Escherichia coli O 157. H7 producing verocytotoxin (VT), took place following a christening party in Birmingham in June 1987. Twenty-six people were affected, six were admitted to hospital and one developed haemolytic uraemic syndrome: there were no deaths. VT + E. coli O 157. H7 was isolated from 13 (57%) of 23 faecal specimens from affected people and from 3 (9%) of 33 specimens from asymptomatic people. Free VT was detected in the faeces of one further asymptomatic person. Illness was associated with eating turkey-roll sandwiches (P < 0·001) suggesting that cold meats might be an important source of infection.
Using DNA probes specific for the genes encoding Vero cytotoxins 1 and 2 in hybridization experiments on faecal samples. Vero cytotoxin-producing Escherichia coli (VTEC) of serogroup 0 157 were detected in 21 of 63 cases of haemorrhagic colitis, 9 of 31 cases of non-bloody diarrhoea and 14 of 68 cases of haemolytic uraemic syndrome. Compared with these results sorbitol-MacConkey agar in conjunction with a specific 0 157 antiserum gave a sensitivity of 62% in haemorrhagic colitis, 56% in non-bloody diarrhoea and 57% in haemolytic uraemic syndrome.The specificity of this method was 100% in all three groups. This demonstrates that sorbitol-MacConkey agar is a useful screening method for the detection of VTEC of serogroup O 157 when used in conjunction with a specific homologous antiserum. However, this method does not detect VTEC belonging to other serogroups and such strains were found, particularly in cases of haemolytic uraemic syndrome.
A method of controlling outbreaks of streptococcal infection of the upper respiratory tract in communities such as boarding schools is described.
It is suggested that, in a search for carriers, nose and mouth swabs should be taken in place of the customary nose and throat swabs. These swabs will detect those who are dispersing streptococci into the environment, as distinct from the carriers who are not dispersers. It is essential that infections of the skin and ears should also be looked for.
It is recommended that all dispersers, whether nose or mouth positive, should receive sulphanilamide insufflation in both nostrils twice daily for a week, or longer if necessary, without exclusion from school. In addition, penicillin lozenges for 2 days may be recommended for the mouth positives only.
The history is considered to be an important factor in deciding the extent of the initial investigation, and examples are given to illustrate this. When mass swabbing is considered necessary, it is highly desirable that the whole community should be swabbed at the same time, as early as possible in the outbreak. It is also desirable that bacteriological follow-up should be available to check that control has been effected.
This paper presents a summary of the principles and processes used to design a ski-jump ramp profile for the UK’s Future Aircraft Carrier (CVF) optimised for the Joint Strike Fighter (JSF).
The paper includes an overview of the CVF and JSF programs, a history and summary of the ski-jump ramp and the principles of its use in the shipborne Short Take-Off (STO) manoeuvre.
The paper discusses the importance of defining optimisation boundaries including specified objectives, aircraft configurations and environmental conditions. It then demonstrates the process of balancing the design drivers of air vehicle performance and landing gear loads to achieve an optimum profile. Comparisons are made between the proposed candidate CVF ramp profile and the current in service ski-jump design as designed for the Harrier family of aircraft.
The paper briefly covers some of the important issues and factors that have been experienced when a theoretical profile is translated into a physical ramp fitted to a ship, principally the effects on aircraft operations due to build and in-service variation from the nominal profile.
A study was conducted evaluating the effect of long-term Cu deficiency, with or without high Mn, on growth, gene expression and Cu status of beef cattle. Twenty-one Angus calves were born to cows receiving one of the following treatments: (1) 10 mg supplemental Cu/kg DM (+Cu); (2) no supplemental Cu and 2 mg Mo/kg DM ( − Cu); (3) − Cu diet plus 500 mg supplemental Mn/kg DM ( − Cu+Mn). Calves were weaned at approximately 183 d of age and individually fed throughout the growing and finishing phases. Plasma Cu was lower (P < 0·01) in − Cu calves compared with +Cu calves while high dietary Mn further depressed (P < 0·01) plasma Cu in − Cu+Mn calves v. − Cu calves. Liver Cu concentrations in +Cu calves were greater (P < 0·01) than in − Cu calves, with no differences between − Cu and − Cu+Mn calves. The daily body-weight gain of +Cu calves was greater (P < 0·01) than − Cu calves during the period from birth to weaning, but did not differ during the growing phase. − Cu+Mn calves gained less (P < 0·05) than − Cu calves during the growing phase. DM intake was lower (P < 0·01) in − Cu+Mn calves v. − Cu calves, and did not differ among +Cu and − Cu calves. The relative gene expression of cytochrome c oxidase in the liver was lower (P < 0·05) in − Cu calves compared with +Cu or − Cu+Mn calves. In conclusion, feeding a Cu − deficient diet in combination with high Mn negatively affected the growth and Cu status of beef cattle.
The Solar Mass Ejection Imager (SMEI) was launched into a Sun-synchronous orbit in January 2003. Its mission objective is to detect and track coronal mass ejections (CMEs) from the Sun in order to improve space weather forecasts. In the three years since launch, over 200 CMEs, about 30 of which were Earth-directed, have been observed by SMEI. We have been able to track several of these CMEs from the SOHO LASCO coronagraphs ($<$8$^\circ$ from the Sun) through the SMEI field of view ($>$20$^\circ$) out to 0.5 AU and beyond, and to observe the morphology and evolution of distinctive features over this wide distance range. We report on comparisons of measurements of CME parameters made in the inner heliosphere with the more typical measurements made nearer the Sun with coronagraphs. We illustrate SMEI's capabilities and present key statistical results on basic CME parameters and the use of SMEI-type data in space weather forecasting models. For example, timely observations by SMEI of CMEs en route to Earth could be input to DoD's operational Hakamada-Akasofu-Fry solar wind model to correct or refine its real-time forecasts of approaching disturbances.
Previous studies from our group suggest that the synchronised onset of oestradiol secretion by preimplantation conceptuses from Meishan pigs may contribute to the enhanced prenatal survival characteristic of this breed (Ashworth and Pickard, 1998). We have recently reported that in vitro, the onset of oestradiol secretion by conceptuses can be regulated in a dose-dependent manner by an aromatase inhibitor (letrozole; Ashworth et al., 2005). Before commencing in vivo trials to assess the efficacy of letrozole to promote prenatal survival, it is important to determine whether exogenous letrozole reaches the uterine lumen and to establish the relationship between the dose administered and the impact on oestradiol secretion at the conceptus-uterine interface.
We assessed the architecture of the medial gastrocnemius in nine children (five males, four females; age range 6 to 15 years; mean 10 years 10 months, SD 3 years 6 months) with spastic diplegia by ultrasound imaging before and after a gastrocnemius recession. The children were ambulant (seven independent, one with a posterior walker, one using crutches) before and after surgical intervention. We compared values for fascicle lengths and deep fascicular-aponeurosis angles with those from a group of normally developing children (five males, five females; age range 6 to 11 years; mean 8 years 4 months, SD 1 year 4 months). Despite a variable interval between assessments (from 56 to 610 days), fascicles were shorter (p=0.00226) and the deep fascicular-aponeurosis angle increased (p=0.0152) after intervention. Fascicle lengths of patients were similar to those in the group of normally developing children before surgery. After surgery, fascicles in the group of children with spastic diplegia were shorter than in their normally developing peers (p=0.00109). The gastrocnemius recession procedure alters muscle architecture, though the degree of fascicular shortening varied, with four of the participants in our study losing less than 10% of their original fascicular length at maximum dorsiflexion. Increases in ankle-joint power in walking, observed after surgical intervention in children with spastic diplegia, may be due to a more normal ankle position rather than to improvements in the active mechanical performance of the gastrocnemius.
Let X be a separable Banach space which admits a C1-smooth norm, and let G ⊂ X be an open subset. Then any real-valued, bounded and uniformly continuous map on G can be uniformly approximated on G by C1-smooth functions with bounded derivative.
We give a characterisation for the extension of uniformly smooth norms from subspaces Y of superreflexive spaces X to uniformly smooth norms on all of X. This characterisation is applied to obtain results in various contexts.
Bladder, or detrusor, instability is a symptomatic condition which is characterized by uncontrollable rises in pressure within the bladder lumen leading to a feeling of urgency of micturition and, if severe enough, urinary incontinence. The rises in pressure are brought about by contraction of the detrusor smooth muscle which forms the major tissue component of the urinary bladder wall. This abnormality can be associated with a number of clinical conditions and when there is evidence of associated neurological deficits it is termed detrusor hyper-reflexia. An increase in bladder outflow resistance is also associated with detrusor instability and this is especially prevalent in men due to the age-related hypertrophy of the prostate gland which surrounds the urethra. However, in the majority of cases the cause is idiopathic and probably multifactorial. No matter what the cause, detrusor instability is one the largest causes of morbidity in the community; in the UK its prevalence increases from about 2 % in men and 9 % in women aged 15-64 years to 7 % and 12 %, respectively, in the over 65 years age group (Thomas et al. 1980; Brocklehurst, 1993).
The passive and active electrical properties of left ventricular myocardium were measured, using conducted action potentials and current clamp of isolated myocytes. The objective was to quantify changes of intracellular resistivity, Ri, during hypertrophic growth and the simultaneous imposition of cellular hypoxia. Ri was estimated from the time course of the rising phase of a conducted action potential using a solution of the two-dimensional cable equation. The thoracic aorta of guinea-pigs was constricted to induce left ventricular hypertrophy (LVH) and myocardium used 50 and 150 days post-operation. Conduction velocity increased in the earlier stage of LVH and declined in the later stage, compared with age-matched controls. Hypoxia reduced conduction velocity in all experimental groups. Ri increased only in the later stage of hypertrophy (253 ± 39 [Omega] cm to 544 ± 130 [Omega] cm) and was additionally increased by hypoxia in all groups (e.g. control myocardium 252 ± 39 [Omega] cm to 506 ± 170 [Omega] cm). The magnitude of the increase of Ri in hypertrophied, hypoxic myocardium can create conditions required to generate re-entrant arrhythmias.