Liquid Structure of Shock-Compressed Hydrocarbons at Megabar Pressures

We present results for the ionic structure in hydrocarbons (polystyrene, polyethylene) that were shock compressed to pressures of up to 190 GPa, inducing rapid melting of the samples. The structure of the resulting liquid is then probed using in situ diffraction by an x-ray free electron laser beam, demonstrating the capability to obtain reliable diffraction data in a single shot, even for low-Z samples without long range order. The data agree well with ab initio simulations, validating the ability of such approaches to model mixed samples in states where complex interparticle bonds remain, and showing that simpler models are not necessarily valid. While the results clearly exclude the possibility of complete carbon-hydrogen demixing at the conditions probed, they also, in contrast to previous predictions, indicate that diffraction is not always a sufficient diagnostic for this phenomenon.

Compact high energy x-ray spectrometer based on forward Compton scattering for high intensity laser plasma experiments

This article describes the design and presents recent results from testing and calibration of a forward Compton scattering high energy X-ray spectrometer. The calibration was performed using a bremsstrahlung source on the photon scattering facility at the γ Electron linac for beams with high brilliance and low emittance accelerator at Helmholtz-Zentrum Dresden-Rossendorf, which provides high energy X-ray photons with energies up to 18 MeV. The calibration was conducted at different bremsstrahlung end point energies-10.5, 13, 15, and 18 MeV. Experimental spectra show a systematic increase in the maximum energy, photon temperature, and flux. The spectrometer is effective for an energy range of 4-20 MeV with 20%-30% energy resolution. The spectrometer operates in low vacuum with pressure less than 0.1 mbar. Experimental tests showed that operating such a spectrometer in air causes a spuriously enhanced high energy signal due to Compton scattering of photons within air. The article also describes the design and shielding considerations which helped to achieve a dynamic range greater than 30 with this spectrometer. The comparison between the experimental results and Monte Carlo simulations are also presented.

Electron temperature scaling in laser interaction with solids

A precise knowledge of the temperature and number of hot electrons generated in the interaction of short-pulse high-intensity lasers with solids is crucial for harnessing the energy of a laser pulse in applications such as laser-driven ion acceleration or fast ignition. Nevertheless, present scaling laws tend to overestimate the hot electron temperature when compared to experiment and simulations. We present a novel approach that is based on a weighted average of the kinetic energy of an ensemble of electrons. We find that the scaling of electron energy with laser intensity can be derived from a general Lorentz invariant electron distribution ansatz that does not rely on a specific model of energy absorption. The scaling derived is in perfect agreement with simulation results and clearly follows the trend seen in recent experiments, especially at high laser intensities where other scalings fail to describe the simulations accurately.

Biofilms and their management: from concept to clinical reality

How can a better understanding of wound biofilms change your clinical practice? And what is the likely impact on clinical outcomes? At this year's JWC lecture, sponsored by sorbion, two of the world's leading microbiologists, Steve Percival and Randy Wolcott, answered these questions. Steve Percival explained what a wound biofilm is, and what diagnostic and management techniques can be used to overcome it. Randy Wolcott described the astonishing success this can bring, with healing rates of up 90% being recorded in patients with recalcitrant chronic wounds.

Absolute charge calibration of scintillating screens for relativistic electron detection

We report on new charge calibrations and linearity tests with high-dynamic range for eight different scintillating screens typically used for the detection of relativistic electrons from laser-plasma based acceleration schemes. The absolute charge calibration was done with picosecond electron bunches at the ELBE linear accelerator in Dresden. The lower detection limit in our setup for the most sensitive scintillating screen (KODAK Biomax MS) was 10 fC/mm(2). The screens showed a linear photon-to-charge dependency over several orders of magnitude. An onset of saturation effects starting around 10-100 pC/mm(2) was found for some of the screens. Additionally, a constant light source was employed as a luminosity reference to simplify the transfer of a one-time absolute calibration to different experimental setups.

Enhanced isochoric heating from fast electrons produced by high-contrast, relativistic-intensity laser pulses

Thin, mass-limited targets composed of V/Cu/Al layers with diameters ranging from 50 to 300 microm have been isochorically heated by a 300 fs laser pulse delivering up to 10 J at 2x10{19} W/cm{2} irradiance. Detailed spectral analysis of the Cu x-ray emission indicates that the highest temperatures, of the order of 100 eV, have been reached when irradiating the smallest targets with a high-contrast, frequency-doubled pulse despite a reduced laser energy. Collisional particle-in-cell simulations confirm the detrimental influence of the preformed plasma on the bulk target heating.

Impacts of feeding system and season on milk composition and Cheddar cheese yield in a subtropical environment

Milk obtained from cows on 2 subtropical dairy feeding systems were compared for their suitability for Cheddar cheese manufacture. Cheeses were made in a small-scale cheesemaking plant capable of making 2 blocks (about 2 kg each) of Cheddar cheese concurrently. Its repeatability was tested over 10 separate cheesemaking days with no significant differences being found between the 2 vats in cheesemaking parameters or cheese characteristics. In the feeding trial, 16 pairs of Holstein–Friesian cows were used in 2 feeding systems (M1, rain-grown tropical grass pastures and oats; and M5, a feedlot, based on maize/barley silage and lucerne hay) over 2 seasons (spring and autumn corresponding to early and late lactation, respectively). Total dry matter, crude protein (kg/cow.day) and metabolisable energy (MJ/cow.day) intakes were 17, 2.7, and 187 for M1 and 24, 4, 260 for M5, respectively. M5 cows produced higher milk yields and milk with higher protein and casein levels than the M1 cows, but the total solids and fat levels were similar (P > 0.05) for both M1 and M5 cows. The yield and yield efficiency of cheese produced from the 2 feeding systems were also not significantly different. The results suggest that intensive tropical pasture systems can produce milk suitable for Cheddar cheese manufacture when cows are supplemented with a high energy concentrate. Season and stage of lactation had a much greater effect than feeding system on milk and cheesemaking characteristics with autumn (late lactation) milk having higher protein and fat contents and producing higher cheese yields.

Dynamics of electric fields driving the laser acceleration of multi-MeV protons

The acceleration of multi-MeV protons from the rear surface of thin solid foils irradiated by an intense (approximately 10(18) W/cm2) and short (approximately 1.5 ps) laser pulse has been investigated using transverse proton probing. The structure of the electric field driving the expansion of the proton beam has been resolved with high spatial and temporal resolution. The main features of the experimental observations, namely, an initial intense sheath field and a late time field peaking at the beam front, are consistent with the results from particle-in-cell and fluid simulations of thin plasma expansion into a vacuum.

A victory against MRSA

Patients were being transferred from nursing homes to hospital with MRSA in their PEG sites. The intervention of two nurses has eradicated the problem.

K(alpha) fluorescence measurement of relativistic electron transport in the context of fast ignition

Electron transport within solid targets, irradiated by a high-intensity short-pulse laser, has been measured by imaging K(alpha) radiation from high- Z layers (Cu, Ti) buried in low- Z (CH, Al) foils. Although the laser spot is approximately 10 microm [full width at half maximum (FWHM)], the electron beam spreads to > or =70 microm FWHM within <20 microm of penetration into an Al target then, at depths >100 microm, diverges with a 40 degree spreading angle. Monte Carlo and analytic models are compared to our data. We find that a Monte Carlo model with a heuristic model for the electron injection gives a reasonable fit with our data.

MeV ion jets from short-pulse-laser interaction with thin foils

Collimated jets of carbon and fluorine ions up to 5 MeV/nucleon ( approximately 100 MeV) are observed from the rear surface of thin foils irradiated with laser intensities of up to 5 x 10 (19)W/cm(2). The normally dominant proton acceleration could be surpressed by removing the hydrocarbon contaminants by resistive heating. This inhibits screening effects and permits effective energy transfer and acceleration of other ion species. The acceleration dynamics and the spatiotemporal distributions of the accelerating E fields at the rear surface of the target are inferred from the detailed spectra.

Effect of inner cannula removal on the work of breathing imposed by tracheostomy tubes: a bench study

BACKGROUND

Tracheotomy has been used to assist in weaning patients from mechanical ventilation. Some patients fail to be weaned from the ventilator despite tracheostomy. We hypothesized that removing the inner cannula from the tracheostomy tube would decrease the tube's imposed work of breathing (WOB(IMP)).

METHODS

The hypothesis was tested using a lung model, by measuring the change in WOB(IMP) when the inner cannula was removed. A mechanical lung model was developed using a test lung to simulate a spontaneously breathing patient. WOB(IMP) was measured with a commercially available lung mechanics monitor. Shiley size 6, 8, and 10 nonfenestrated tracheostomy tubes were tested with the inner cannula in and out. Breathing conditions were simulated using tidal volumes (V(T)) of 300 and 500 mL matched with breathing frequencies of 12, 24, and 32 breaths per minute, by using a ventilator to simulate spontaneous breathing through one side of the test lung.

RESULTS

Under all the tested breathing conditions, WOB(IMP) for each of the 3 tracheostomy tubes was significantly reduced (p < 0.05) when the inner cannula was removed. Also, as simulated spontaneous inspiratory flow demand increased (ie, as V(T) and/or frequency were increased), WOB(IMP) also increased, and vice versa. With the cannula removed, WOB(IMP) was not significantly different between the size 6 and 8 tubes nor between the size 8 and 10 tubes when V(T) was 300 mL and frequency was 12 breaths per minute.

CONCLUSIONS

There was a significant decrease in WOB(IMP) with each tube when the inner cannula was removed. WOB(IMP) increased with an increase in inspiratory flow demand (ie, increase in V(T) and/or frequency), as well as when tube size decreased. In weaning a tracheostomized patient from mechanical ventilation, increasing the internal diameter of the tube by removing the inner cannula may be beneficial. Further study is needed to determine if these findings are clinically important.

Does a shift in the T-cell receptor repertoire precede the onset of MS?

BACKGROUND

Utz et al., in a study of identical twins discordant for MS, showed that antigen-stimulated T cells from the MS twins have a major shift in their T-cell receptor (TCR) repertoires when compared with the healthy twins. We hypothesized that a shift in the TCR repertoire precedes the onset of MS and tested this hypothesis by studying unstimulated naive T cells because the TCR repertoires of these cells are largely unaffected by disease.

OBJECTIVE

To investigate whether unstimulated naive T cells from MS patients have a detectable shift in their TCR repertoires.

METHODS

We analyzed the TCR J beta (TCRBJ) repertoires of naive T cells from identical twin pairs discordant for MS, healthy identical twin pairs, healthy unrelated pairs, and unrelated MS patient pairs. The correlation coefficient (r value) was used as a measure of similarity of TCRBJ repertoires in each pair of individuals. Fisher's z transformation was then used to test for the significance of the difference between the r values from different pairs.

RESULTS

The TCRBJ repertoires of the discordant MS twin pairs were significantly different from those of the healthy identical twin pairs, whereas MS patient pairs had TCRBJ repertoires similar to those of the healthy unrelated pairs formed from healthy twin pairs and discordant MS twin pairs.

CONCLUSIONS

MS patients have a major shift in their naive T-cell TCRBJ repertoires compared with healthy individuals, implying that this shift precedes the disease onset. This shift could represent the nongenetic factor that explains MS discordance in genetically identical individuals.

Dimensions of perfectionism, hopelessness, and attempted suicide in a sample of alcoholics

This study assessed whether specific dimensions of perfectionism and hopelessness were elevated in individuals who had made a serious suicide attempt in comparison to individuals with no history of suicide attempts. A sample of 39 inpatients with alcoholism who had made a serious suicide attempt and a matched sample of 39 inpatients with alcoholism but no history of suicide attempts completed the Multidimensional Perfectionism Scale, the Hopelessness Scale, ratings of achievement and social hopelessness, and the Beck Depression Inventory. The attempter group had higher scores on socially prescribed perfectionism, generalized hopelessness, achievement hopelessness, social hopelessness, and depression. A discriminant function analysis revealed that depression, social hopelessness, socially prescribed perfectionism, and other-oriented perfectionism were unique discriminators of the suicide groups. The results are discussed in terms of the importance of social personality variables in attempted suicide.

Type 2 Gaucher disease with hydrops fetalis in an Ashkenazi Jewish family resulting from a novel recombinant allele and a rare splice junction mutation in the glucocerebrosidase locus

Gaucher disease, the deficiency of the lysosomal enzyme glucocerebrosidase (EC 3.2.1.45), is frequently encountered in the Ashkenazi Jewish population. Carrier screening for Gaucher disease by enzyme analysis performed during a routine pregnancy indicated that both Ashkenazi parents were carriers. Screening for four common Gaucher mutations was subsequently performed on fetal and parental DNA. None of the common Ashkenazi mutations were identified. However, when exons 9-11 were amplified and digested with NciI to detect the L444P mutation, it appeared that the mother and the fetus had an unusual allele and that the expected paternal allele was not present. When the fetal amniocytes were found to have less than 2% of the normal glucocerebrosidase activity and a fetal sonogram revealed hydrops fetalis, the pregnancy was terminated. The diagnosis of severe type 2 Gaucher disease was confirmed at autopsy. Ultrastructural studies of epidermis from the fetus revealed the characteristic disruption of lamellar bilayers, diagnostic for type 2 Gaucher disease. In subsequent studies of the fetal DNA, long-template polymerase chain reaction amplification revealed one appropriately sized band (approximately 6.5 kb) and one smaller (approximately 5.2 kb) band. Sequencing of the approximately 5.2-kb fragment identified a novel fusion allele resulting from recombination between the glucocerebrosidase gene and its pseudogene beginning in intron 3. This fusion allele was inherited from the father. The result was confirmed by Southern blot analysis using the enzyme S8tII. Sequencing of the 6.5-kb fragment identified a previously described, although rare, T-to-G splice junction mutation in intron 10 of the maternal allele, which introduced an NciI site. The couple had a subsequent pregnancy which was also found to be affected. This case study identifies a novel recombinant allele and an unusual splice junction mutation, and demonstrates that even in the Ashkenazi population, screening for common mutations may not accurately identify the most severe forms of the disease.

Dynamic systems for pressure sore prevention

Dynamic support systems are designed for the prevention and management of pressure sores in medium- to very-high-risk patients. Careful patient assessment is required for the effective use of these support systems. The selected product must be comfortable and acceptable to the patient.

Patient-controlled analgesia devices

PCA is associated with a reduced length of hospital stay and savings in nursing time and resources. Pre-operative patient education is required for the successful use of PCA. Regular patient and equipment monitoring is vital to ensure effective pain relief.

Sterilising solutions for heat-sensitive instruments

Disinfectants should be used only to decontaminate heat-sensitive medical equipment. A COSHH risk assessment is required to ensure the safe use of disinfectants. Equipment and processing manufacturers should be consulted before using any of the alternatives to glutaraldehyde.

Compression hosiery

A wide range of compression hosiery is available for a range of conditions. Involving patients in the selection process will help ensure that the chosen product is suited to the individual's needs and preferences. Accurate measurement is required for a good fit and comfort.

Pressure-relief seating

Chair-bound patients are significantly at risk of developing pressure sores. Little comparative research has been undertaken on pressure-relief seating. An understanding of a patient's requirements for pressure-relief seating will help when selecting products from the huge range available.

Pulse oximeters

Pulse oximetry is a reliable and non-invasive method of measuring oxygen saturation. An understanding of the principles of operation is required to ensure its effective use. It is important to check the patient's history to ensure there are no factors which may cause monitoring problems.

Patient moving and handling equipment

Current regulations recommend that manual lifting should be avoided whenever possible. An ergonomic approach, based on full risk assessment and the use of moving and handling aids, will significantly reduce the risk of back strain and musculoskeletal injury. Ongoing training is required on manual handling techniques and equipment.

Blood glucose monitoring devices

Blood glucose monitoring can enable people to control their diabetes. People with diabetes will be motivated to continue monitoring only if it is seen to be effective. Patient education will significantly influence people's attitude to blood glucose monitoring, and must reflect individual needs and circumstances.

Pressure support systems for hospital use

The range of pressure support systems is constantly increasing. Accurate assessment will assist the selection process. Practical considerations and cost implications must also be taken into account when selecting a product.

Intravenous infusion pumps for hospital use

Infusion pumps provide safe and accurate delivery of intravenous fluids. Accuracy can be ensured only if the devices are used correctly. Full training is required in order to gain maximum benefit from these devices.

Ambulatory blood pressure monitors

ABPM automatically records blood pressure at preset intervals over a 24-hour period. By establishing average blood pressure, cases of white-coat hypertension and borderline hypertension can be identified. The use of ABPM is likely to increase in the near future, therefore it is important that nurses become more aware of the technique.

Catheters designed for intermittent use

Intermittent catheterisation can improve patients' quality of life and promote independence. There is considerable lack of awareness about the technique. Nurses need to be aware of the products available to ensure patients receive appropriate treatment.

Nebulisers for use in the community

A wide range of nebulisers is available for the treatment of various types of respiratory disease. Patient information is required on assembling the nebuliser and inhalation technique. Servicing and maintenance requirements are often overlooked by both patients and nurses.

Pressure-reducing aids for community use

The need for effective pressure support systems is often overlooked in the community. Through patient assessment is required for the selection of pressure-reducing aids. Patients should be involved in the selection process, and any equipment chosen must be suitable for the home environment.

Missed appointments and Medicaid managed care

OBJECTIVES

To compare the demographic characteristics of patients who miss appointments with those who do not and to identify subgroups who would benefit from specific interventions for improving attendance.

DESIGN

Retrospective cohort study of an 18-month period.

SETTING

An urban primary care practice.

PATIENTS

A random sample (N = 477) of patients who were seen at least twice during the study period.

MAIN OUTCOME MEASURES

Number of missed visits and kept visits, insurer, age, sex, race, ZIP code, and diagnoses.

RESULTS

Of the established patients, 48% missed 1 or more visits. Patients in managed care programs, private and Medicaid, were likely to have missed more visits during the study period than those not in managed care programs (P < .001). Medicaid managed care patients had also scheduled more visits. Significantly higher rates of missed appointments were found in patients aged 19 to 35 years (P = .02), blacks (P < .001), patients in Medicaid managed care programs (P < .001), and patients who scheduled more visits (P < .001). After adjusting for age, race, and sex, Medicaid managed care insurance remained a significant (P < .01) predictor of rate of missed appointments.

CONCLUSIONS

Patients in managed care programs missed more appointments. Patients in Medicaid managed care programs scheduled more appointments and had higher rates of missed appointments than their counterparts in other insurance groups.