Colloid thruster technology

A program is described for attaining control, reproducibility, and predictability of operation for the annular colloid emitter. A thruster of an improved design was used for a 1000 hour test. The thruster was operated with a neutralizer for 1023 hours at 15 kV with an average thrust of 25 micropound and specific impulse of 1160 sec. The performance was stable, and the beam was vectored periodically. The clean condition of the emitter edge at the end of the test coupled with no degradation in performance during the test indicated that the lifetime could be extrapolated by at least an order of magnitude over the test time

Magnetic field effect on tunnel ionization of deep impurities by terahertz radiation

A suppression of tunnelling ionization of deep impurities in terahertz frequency electric fields by a magnetic field is observed. It is shown that the ionization probability at external magnetic field, B, oriented perpendicular to the electric field of terahertz radiation, E, is substantially smaller than that at B || E. The effect occurs at low temperatures and high magnetic fields

Transient quantum evolution of 2D electrons under photoexcitation of a deep center

We have considered the ballistic propagation of the 2D electron Wigner distribution, which is excited by an ultrashort optical pulse from a short-range impurity into the first quantized subband of a selectively-doped heterostructure with high mobility. Transient ionization of a deep local state into a continuum conduction c-band state is described. Since the quantum nature of the photoexcitation, the Wigner distribution over 2D plane appears to be an alternating-sign function. Due to a negative contribution to the Wigner function, the mean values (concentration, energy, and flow) demonstrate an oscillating transient evolution in contrast to the diffusive classical regime of propagation.Comment: 8 pages, 6 figures, pape

Mobile phone-based interventions for improving adherence to medication prescribed for the primary prevention of cardiovascular disease in adults.

BACKGROUND: Cardiovascular disease (CVD) is a major cause of disability and mortality globally. Premature fatal and non-fatal CVD is considered to be largely preventable through the control of risk factors via lifestyle modifications and preventive medication. Lipid-lowering and antihypertensive drug therapies for primary prevention are cost-effective in reducing CVD morbidity and mortality among high-risk people and are recommended by international guidelines. However, adherence to medication prescribed for the prevention of CVD can be poor. Approximately 9% of CVD cases in the EU are attributed to poor adherence to vascular medications. Low-cost, scalable interventions to improve adherence to medications for the primary prevention of CVD have potential to reduce morbidity, mortality and healthcare costs associated with CVD. OBJECTIVES: To establish the effectiveness of interventions delivered by mobile phone to improve adherence to medication prescribed for the primary prevention of CVD in adults. SEARCH METHODS: We searched CENTRAL, MEDLINE, Embase, and two other databases on 21 June 2017 and two clinical trial registries on 14 July 2017. We searched reference lists of relevant papers. We applied no language or date restrictions. SELECTION CRITERIA: We included randomised controlled trials investigating interventions delivered wholly or partly by mobile phones to improve adherence to cardiovascular medications prescribed for the primary prevention of CVD. We only included trials with a minimum of one-year follow-up in order that the outcome measures related to longer-term, sustained medication adherence behaviours and outcomes. Eligible comparators were usual care or control groups receiving no mobile phone-delivered component of the intervention. DATA COLLECTION AND ANALYSIS: We used standard methodological procedures recommended by Cochrane. We contacted study authors for disaggregated data when trials included a subset of eligible participants. MAIN RESULTS: We included four trials with 2429 randomised participants. Participants were recruited from community-based primary care or outpatient clinics in high-income (Canada, Spain) and upper- to middle-income countries (South Africa, China). The interventions received varied widely; one trial evaluated an intervention focused on blood pressure medication adherence delivered solely through short messaging service (SMS), and one intervention involved blood pressure monitoring combined with feedback delivered via smartphone. Two trials involved interventions which targeted a combination of lifestyle modifications, alongside CVD medication adherence, one of which was delivered through text messages, written information pamphlets and self-completion cards for participants, and the other through a multi-component intervention comprising of text messages, a computerised CVD risk evaluation and face-to-face counselling. Due to heterogeneity in the nature and delivery of the interventions, we did not conduct a meta-analysis, and therefore reported results narratively.We judged the body of evidence for the effect of mobile phone-based interventions on objective outcomes (blood pressure and cholesterol) of low quality due to all included trials being at high risk of bias, and inconsistency in outcome effects. Of two trials targeting medication adherence alongside other lifestyle modifications, one reported a small beneficial intervention effect in reducing low-density lipoprotein cholesterol (mean difference (MD) -9.2 mg/dL, 95% confidence interval (CI) -17.70 to -0.70; 304 participants), and the other found no benefit (MD 0.77 mg/dL, 95% CI -4.64 to 6.18; 589 participants). One trial (1372 participants) of a text messaging-based intervention targeting adherence showed a small reduction in systolic blood pressure (SBP) for the intervention arm which delivered information-only text messages (MD -2.2 mmHg, 95% CI -4.4 to -0.04), but uncertain evidence of benefit for the second intervention arm that provided additional interactivity (MD -1.6 mmHg, 95% CI -3.7 to 0.5). One study examined the effect of blood pressure monitoring combined with smartphone messaging, and reported moderate intervention benefits on SBP and diastolic blood pressure (DBP) (SBP: MD -7.10 mmHg, 95% CI -11.61 to -2.59; DBP: -3.90 mmHg, 95% CI -6.45 to -1.35; 105 participants). There was mixed evidence from trials targeting medication adherence alongside lifestyle advice using multi-component interventions. One trial found large benefits for SBP and DBP (SBP: MD -12.45 mmHg, 95% CI -15.02 to -9.88; DBP: MD -12.23 mmHg, 95% CI -14.03 to -10.43; 589 participants), whereas the other trial demonstrated no beneficial effects on SBP or DBP (SBP: MD 0.83 mmHg, 95% CI -2.67 to 4.33; DBP: MD 1.64 mmHg, 95% CI -0.55 to 3.83; 304 participants).Two trials reported on adverse events and provided low-quality evidence that the interventions did not cause harm. One study provided low-quality evidence that there was no intervention effect on reported satisfaction with treatment.Two trials were conducted in high-income countries, and two in upper- to middle-income countries. The interventions evaluated employed between three and 16 behaviour change techniques according to coding using Michie's taxonomic method. Two trials evaluated interventions that involved potential users in their development. AUTHORS' CONCLUSIONS: There is low-quality evidence relating to the effects of mobile phone-delivered interventions to increase adherence to medication prescribed for the primary prevention of CVD; some trials reported small benefits while others found no effect. There is low-quality evidence that these interventions do not result in harm. On the basis of this review, there is currently uncertainty around the effectiveness of these interventions. We identified six ongoing trials being conducted in a range of contexts including low-income settings with potential to generate more precise estimates of the effect of primary prevention medication adherence interventions delivered by mobile phone

Coupling theory for counterion distributions based in Tsallis statistics

It is well known that the Poisson-Boltzmann (PB) equation yields the exact counterion density around charged objects in the weak coupling limit. In this paper we generalize the PB approach to account for coupling of arbitrary strength by making use of Tsallis q-exponential distributions. Both the weak coupling and the strong coupling limits are reproduced. For arbitrary coupling we also provide simple analytical expressions which are compared to recent Monte Carlo simulations by A. G. Moreira and R. R. Netz [Europhys. Lett. 52 (2000) 705]. Excellent agreement with these is obtained.Comment: 17 pages, 2 figures, 1 table. Final version, accepted for publication in Physica

Spatial structure of an individual Mn acceptor in GaAs

The wave function of a hole bound to an individual Mn acceptor in GaAs is spatially mapped by scanning tunneling microscopy at room temperature and an anisotropic, cross-like shape is observed. The spatial structure is compared with that from an envelope-function, effective mass model, and from a tight-binding model. This demonstrates that anisotropy arising from the cubic symmetry of the GaAs crystal produces the cross-like shape for the hole wave-function. Thus the coupling between Mn dopants in GaMnAs mediated by such holes will be highly anisotropic.Comment: 3 figures, submitted to PR

Why and when the Minkowski's stress tensor can be used in the problem of Casimir force acting on bodies embedded in media

It is shown that the criticism by Raabe and Welsch of the Dzyaloshinskii-Lifshitz-Pitaevskii theory of the van der Waals-Casimir forces inside a medium is based on misunderstandings. It is explained why and at which conditions one can use the ''Minkowski-like '' stress tensor for calculations of the forces. The reason, why approach of Raabe and Welsch is incorrect, is discussed.Comment: Comment, 2 pages. 2 misprints were correcte