Laser-direct-drive fusion target design with a high-Z gradient-density pusher shell.

Laser-direct-drive fusion target designs with solid deuterium-tritium (DT) fuel, a high-Z gradient-density pusher shell (GDPS), and a Au-coated foam layer have been investigated through both 1D and 2D radiation-hydrodynamic simulations. Compared with conventional low-Z ablators and DT-push-on-DT targets, these GDPS targets possess certain advantages of being instability-resistant implosions that can be high adiabat (α≥8) and low hot-spot and pusher-shell convergence (CR_{hs}≈22 and CR_{PS}≈17), and have a low implosion velocity (v_{imp}<3×10^{7}cm/s). Using symmetric drive with laser energies of 1.9 to 2.5MJ, 1D lilac simulations of these GDPS implosions can result in neutron yields corresponding to ≳50-MJ energy, even with reduced laser absorption due to the cross-beam energy transfer (CBET) effect. Two-dimensional draco simulations show that these GDPS targets can still ignite and deliver neutron yields from 4 to ∼10MJ even if CBET is present, while traditional DT-push-on-DT targets normally fail due to the CBET-induced reduction of ablation pressure. If CBET is mitigated, these GDPS targets are expected to produce neutron yields of >20MJ at a driven laser energy of ∼2MJ. The key factors behind the robust ignition and moderate energy gain of such GDPS implosions are as follows: (1) The high initial density of the high-Z pusher shell can be placed at a very high adiabat while the DT fuel is maintained at a relatively low-entropy state; therefore, such implosions can still provide enough compression ρR>1g/cm^{2} for sufficient confinement; (2) the high-Z layer significantly reduces heat-conduction loss from the hot spot since thermal conductivity scales as ∼1/Z; and (3) possible radiation trapping may offer an additional advantage for reducing energy loss from such high-Z targets.

Time-dependent density-functional-theory calculations of the nonlocal electron stopping range for inertial confinement fusion applications.

Nonlocal electron transport is important for understanding laser-target coupling for laser-direct-drive (LDD) inertial confinement fusion (ICF) simulations. Current models for the nonlocal electron mean free path in radiation-hydrodynamic codes are based on plasma-physics models developed decades ago; improvements are needed to accurately predict the electron conduction in LDD simulations of ICF target implosions. We utilized time-dependent density functional theory (TD-DFT) to calculate the electron stopping power (SP) in the so-called conduction-zone plasmas of polystyrene in a wide range of densities and temperatures relevant to LDD. Compared with the modified Lee-More model, the TD-DFT calculations indicated a lower SP and a higher stopping range for nonlocal electrons. We fit these electron SP calculations to obtain a global analytical model for the electron stopping range as a function of plasma conditions and the nonlocal electron kinetic energy. This model was implemented in the one-dimensional radiation-hydrodynamic code lilac to perform simulations of LDD ICF implosions, which are further compared with simulations by the standard modified Lee-More model. Results from these integrated simulations are discussed in terms of the implications of this TD-DFT-based mean-free-path model to ICF simulations.

Cognitive problems following hematopoietic stem cell transplant: relationships with sleep, depression and fatigue.

Cognitive problems are a significant, persistent concern for patients undergoing hematopoietic stem cell transplant (HSCT). Sleep is important for many cognitive tasks; however, the relationship between sleep and cognitive problems for HSCT patients is unknown. This study examined the relationship between sleep and cognitive problems for HSCT patients from pre to post transplant. Patients undergoing HSCT (N=138) completed questionnaires at pre-transplant and during the 12 months following transplant. Questionnaires assessed sleep and cognitive problems as well as commonly co-occurring symptoms: depressive symptoms, fatigue and pain. Post hoc analyses examined the relationship of specific sleep problems with cognitive problems. Sleep problems covaried with cognitive problems even after controlling for depressive symptoms, fatigue and pain. Depressive symptoms and fatigue were also uniquely related to cognitive problems. Post hoc analyses suggest that sleep somnolence, shortness of breath, snoring and perceptions of inadequate sleep may contribute to the association found between sleep and cognitive problems. Findings suggest that sleep problems are associated with and may contribute to cognitive problems for HSCT patients. However, sleep problems are rarely screened for or discussed during clinic visits. Assessing and treating specific sleep problems in addition to depressive symptoms and fatigue may have implications for improving cognitive problems for HSCT patients.

Comparison of efficacy of three extractants to solubilize glomalin on hyphae and in soil.

Glomalin, a glycoprotein produced by arbuscular mycorrhizal (AM) fungi, is a major component of the humus fraction of soil organic matter. Glomalin is extracted from soil and hyphae of AM fungi by using sodium citrate at 121 degrees C in multiple 1-h cycles, but extensive extraction does not solubilize all glomalin in all soils. Efficacies of 100 mM sodium salts of citrate, borate or pyrophosphate (pH 9.0, 121 degrees C) were tested for two 1-h cycles for hyphae from four AM fungal isolates and four 1-h cycles for seven soils from four US geographic regions. Residual soil glomalin was examined by pyrophosphate extraction of soils previously extracted with citrate or borate followed by extraction of all soils after treatment with NaOH. Hyphal extracts were compared using Bradford-reactive total protein (BRTP) values, and extracts from soils were compared using BRTP, percentage C and C weight. No difference among extractants was detected for AM fungal isolates or across soils. The residual glomalin across soils for extractants contained the following percentages of the total BRTP: pyrophosphate, 14%; borate, 17%; and citrate, 22%. Comparisons among individual soils indicated that pyrophosphate extracted significantly more BRTP (10-53%) than borate or citrate in six soils and borate was equal to pyrophosphate in one soil. Extraction with borate should be compared with pyrophosphate before initiating an experiment. For routine extractions of ca. 85% of the glomalin across a variety of soils, sodium pyrophosphate appears to be equal to or better than borate and better than citrate.

The role of glomalin, a protein produced by arbuscular mycorrhizal fungi, in sequestering potentially toxic elements.

Naturally occurring soil organic compounds stabilize potentially toxic elements (PTEs) such as Cu, Cd, Pb, and Mn. The hypothesis of this work was that an insoluble glycoprotein, glomalin, produced in copious amounts on hyphae of arbuscular mycorrhizal fungi (AMF) sequesters PTEs. Glomalin can be extracted from laboratory cultures of AMF and from soils. Three different experiments were conducted. Experiment 1 showed that glomalin extracted from two polluted soils contained 1.6-4.3 mg Cu, 0.02-0.08 mg Cd, and 0.62-1.12 mg Pb/g glomalin. Experiment 2 showed that glomalin from hyphae of an isolate of Gigaspora rosea sequestered up to 28 mg Cu/g in vitro. Experiment 3 tested in vivo differences in Cu sequestration by Cu-tolerant and non-tolerant isolates of Glomus mosseae colonizing sorghum. Plants were fed with nutrient solution containing 0.5, 10 or 20 microM of Cu. Although no differences between isolates were detected, mean values for the 20 microM Cu level were 1.6, 0.4, and 0.3 mg Cu/g for glomalin extracted from hyphae, from sand after removal of hyphae and from hyphae attached to roots, respectively. Glomalin should be considered for biostabilization leading to remediation of polluted soils.

A ten-year follow-up of older former problem drinkers: risk of relapse and implications of successfully sustained remission.

OBJECTIVE: This study examines the risk, predictors of relapse and the effects of successfully sustained remission on the drinking behavior, functioning, life context, coping and help seeking of older adults who were problem drinkers earlier in life. METHOD: Older former problem drinkers (n = 447) were prospectively followed for 10 years and compared to lifetime nonproblem drinkers. RESULTS: Of former problem drinkers, 31% (n = 141) died over the 10-year interval, a rate 1.6 times higher than that of lifetime nonproblem drinkers. Among surviving former problem drinkers, although relapse was relatively uncommon (11%), a less severe drinking history, heavier baseline alcohol consumption, and lower baseline income were associated with relapse. The majority (63%) of former problem drinkers who successfully achieved sustained remission continued to drink alcohol, though at levels below those consumed by older lifetime nonproblem drinkers (n = 339). Stably remitted problem drinkers who were abstinent (SRAs) generally reported more severe drinking histories, greater functioning and life context deficits and more help seeking than did stably remitted problem drinkers who were nonabstinent (SRNs). Although SRAs and SRNs both experienced improvements in functioning over the 10-year interval, they continued to experience financial, health-related and life context deficits relative to older lifetime nonproblem drinkers. CONCLUSIONS: Results suggest there are long-term costs associated with earlier drinking problems, even when remission is maintained. Both current drinking behavior and drinking history are worth considering when making recommendations regarding older adults' alcohol consumption.

Psychological care by nurses, paramedical and medical staff: essential developments for the general hospitals.

To date clinical psychologists and psychiatrists have given sparse attention to the development of clinical services within general hospitals, despite a literature demonstrating high levels of need. It is argued that attempts to reverse this situation must resolve long-standing obstacles in attitude and practice within the medical and nursing professions as well as the apparent ambivalence of psychologists and psychiatrists towards the endeavour. If projected developments are to hold credence, planned changes in practice must emphasize a preventive approach towards psychological care and must do this primarily through existing resources; that is, the nursing and paramedical professions. A scheme of psychological care designed to be operated by nurses and other professions is outlined. It depends on teaching and supervision by psychologists and psychiatrists, and it emphasizes the basic skills of monitoring psychological state, caring by informing, emotional care and basic counselling. The absorption of these practices into the daily routine is essential in order that psychological care becomes a standard provision for all seriously ill and injured people. Approaches to training are reviewed and an overview is given of the author's experiences in promoting such a scheme within a renal unit.

An investigation of distress and discontent in various types of nursing.

It has been claimed that nurses in intensive therapy units are prone to high levels of distress and discontent. A questionnaire was designed to assess nurses' reactions to intensive therapy work and thus provide an object check on these claims. Nurses from eight intensive therapy units in England took part in the survey together with comparison groups from two renal units, a medical ward and a surgical ward. High levels of job satisfaction were registered in all the intensive treatment units with very few nurses indicating distress or a wish to leave their job. Some features of the work did attract criticism though, in particular the large fluctuations in work load, the level and adequacy of support, and the sparse amount of feedback given to nurses by senior staff. Much the same pattern was recorded with the medical and surgical nurses, and from one of the renal units. The second renal unit was known to be in a state of crisis at the time and it was predicted that a high level of discontent would be registered there. This proved to be the case and was taken as conformation of the validity of the questionnaire, and also as giving insight into the psycho-social conditions which may foster distress in nurses.