A comparative DFT study of electronic properties of 2H-, 4H- and 6H-SiC(0001) and SiC(000-1) clean surfaces: Significance of the surface Stark effect

Electric field, uniform within the slab, emerging due to Fermi level pinning at its both sides is analyzed using DFT simulations of the SiC surface slabs of different thickness. It is shown that for thicker slab the field is nonuniform and this fact is related to the surface state charge. Using the electron density and potential profiles it is proved that for high precision simulations it is necessary to take into account enough number of the Si-C layers. We show that using 12 diatomic layers leads to satisfactory results. It is also demonstrated that the change of the opposite side slab termination, both by different type of atoms or by their location, can be used to adjust electric field within the slab, creating a tool for simulation of surface properties, depending on the doping in the bulk of semiconductor. Using these simulations it was found that, depending on the electric field, the energy of the surface states changes in a different way than energy of the bulk states. This criterion can be used to distinguish Shockley and Tamm surface states. The electronic properties, i.e. energy and type of surface states of the three clean surfaces: 2H-, 4H-, 6H-SiC(0001), and SiC($000 \bar{1}$) are analyzed and compared using field dependent DFT simulations.Comment: 18 pages, 10 figures, 4 table

Two-Dimensional Diffusion in the Presence of Topological Disorder

How topological defects affect the dynamics of particles hopping between lattice sites of a distorted, two-dimensional crystal is addressed. Perturbation theory and numerical simulations show that weak, short-ranged topological disorder leads to a finite reduction of the diffusion coefficient. Renormalization group theory and numerical simulations suggest that longer-ranged disorder, such as that from randomly placed dislocations or random disclinations with no net disclinicity, leads to subdiffusion at long times.Comment: 10 pages, 6 figure

Wielowymiarowe postawy wobec zmian organizacyjnych pracowników organizacji publicznych

Change is a phenomenon inherent in the functioning of all organizations, including public organizations. Introducing changes is inextricably connected with reluctance and resistance from employees. For the purpose of this article, it was assumed that resistance should be perceived as a multidimensional attitude towards change, including affective, cognitive and behavioral components. The aim of the conducted research is to identify statements describing attitudes towards changes and their assessment by employees of public organizations. A survey questionnaire, including 14 statements that were evaluated by employees of various public organizations, was applied. The obtained research results in most cases indicated pessimistic attitudes of employees towards the introduced changes resulting primarily from: fatigue with the changes introduced, not taking into account the fact that constant changes destroy relationships between people, and the fear of loss of employees as a result of the changes. The assessment of attitudes varied significantly, in particular through the type of institution and the level of involvement of employees in the implementation of the changes resulting from the functions performed or qualifications.Zmiana jest zjawiskiem nieodłącznie związanym z funkcjonowaniem wszystkich organizacji, w tym także organizacji publicznych. Wprowadzanie zmian wiąże się z niechęcią i oporem ze strony pracowników. Na użytek badań zawartych w niniejszym artykule przyjęto, że opór należy postrzegać jako wielowymiarową postawę wobec zmiany, obejmującą komponenty afektywne, poznawcze i behawioralne. Celem przeprowadzonych badań jest identyfikacja stwierdzeń opisujących postawy wobec zmian i ich ocena przez pracowników organizacji publicznych. Kwestionariusz ankiety zawierał 14 stwierdzeń, które oceniane były przez pracowników różnych organizacji publicznych. Uzyskane wyniki badań w większości przypadków wskazują na pesymistyczne postawy pracowników wobec wprowadzonych zmian wynikające przede wszystkim ze zmęczenia wprowadzanymi zmianami, nieuwzględniania przez organizacje faktu, że ciągłe zmiany niszczą relacje między ludźmi, oraz obawy przed utratą pracowników na skutek przeprowadzanych zmian. Ocena postaw jest istotnie zróżnicowane w szczególności poprzez rodzaj instytucji oraz poziom zaangażowania pracowników w implementację zmian, będący wynikiem pełnionych funkcji czy kwalifikacji

An examination of health care utilization during the COVID-19 pandemic among women with early-stage hormone receptor-positive breast cancer

Background: Women undergoing treatment for breast cancer require frequent clinic visits for maintenance of therapy. With COVID-19 causing health care disruptions, it is important to learn about how this population’s access to health care has changed. This study compares self-reported health care utilization and changes in factors related to health care access among women treated at a cancer center in the mid-South US before and during the pandemic. Methods: Participants (N = 306) part of a longitudinal study to improve adjuvant endocrine therapy (AET) adherence completed pre-intervention baseline surveys about their health care utilization prior to AET initiation. Questions about the impact of COVID-19 were added after the pandemic started assessing financial loss and factors related to care. Participants were categorized into three time periods based on the survey completion date: (1) pre-COVID (December 2018 to March 2020), (2) early COVID (April 2020 – December 2020), and later COVID (January 2021 to June 2021). Negative binomial regression analyses used to compare health care utilization at different phases of the pandemic controlling for patient characteristics. Results: Adjusted analyses indicated office visits declined from pre-COVID, with an adjusted average of 17.7 visits, to 12.1 visits during the early COVID period (p = 0.01) and 9.9 visits during the later COVID period (p < 0.01). Hospitalizations declined from an adjusted average 0.45 admissions during early COVID to 0.21 during later COVID, after vaccines became available (p = 0.05). Among COVID period participants, the proportion reporting changes/gaps in health insurance coverage increased from 9.5% participants during early-COVID to 14.8% in the later-COVID period (p = 0.05). The proportion reporting financial loss due to the pandemic was similar during both COVID periods (34.3% early- and 37.7% later-COVID, p = 0.72). The proportion of participants reporting delaying care or refilling prescriptions decreased from 15.2% in early-COVID to 4.9% in the later-COVID period (p = 0.04). Conclusion: COVID-19 caused disruptions to routine health care for women with breast cancer. Patients reported having fewer office visits at the start of the pandemic that continued to decrease even after vaccines were available. Fewer patients reported delaying in-person care as the pandemic progressed.National Cancer Institute ; Division of Cancer Prevention, National Cancer Institute ; Center for Strategic Scientific Initiatives, National Cancer Institute ; Division of Cancer Epidemiology and Genetics, National Cancer Institut

Ba3Ga3N5 - A Novel Host Lattice for Eu2+ - Doped Luminescent Materials with Unexpected Nitridogallate Substructure

The alkaline earth nitridogallate Ba3Ga3N5 was synthesized from the elements in a sodium flux at 760°C utilizing weld shut tantalum ampules. The crystal structure was solved and refined on the basis of single-crystal X-ray diffraction data. Ba3Ga3N5 (space group C2/c (No. 15), a = 16.801(3), b = 8.3301(2), c = 11.623(2) Å, β = 109.92 (3)°, Z = 8) contains a hitherto unknown structural motif in nitridogallates, namely, infinite strands made up of GaN4 tetrahedra, each sharing two edges and at least one corner with neighboring GaN4 units. There are three Ba2+ sites with coordination numbers six or eight, respectively, and one Ba2+ position exhibiting a low coordination number 4 corresponding to a distorted tetrahedron. Eu2+ - doped samples show red luminescence when excited by UV irradiation at room temperature. Luminescence investigations revealed a maximum emission intensity at 638 nm (FWHM =2123 cm−1). Ba3Ga3N5 is the first nitridogallate for which parity allowed broadband emission due to Eu2+ - doping has been found. The electronic structure of both Ba3Ga3N5 as well as isoelectronic but not isostructural Sr3Ga3N5 was investigated by DFT methods. The calculations revealed a band gap of 1.53 eV for Sr3Ga3N5 and 1.46 eV for Ba3Ga3N5

The effectiveness and cost-effectiveness of minimal access surgery amongst people with gastro-oesophageal reflux disease – a UK collaborative study

*Corresponding author randomised arm of the trial (178 allocated to surgical management,179 allocated to continued, but optimised,medical management) and 453 recruited to the parallel non-randomised preference arm (261 chose surgical management, 192 chose to continue with best medical management). The type of fundoplication was left to the discretion of the surgeon. Main outcome measures: Participants completed a baseline reflux questionnaire, developed specifically for this study, containing a disease-specific outcome measure, the Short Form with 36 Items (SF-36), the EuroQol-5 Dimensions (EQ-5D) and the Beliefs about Medicines and Surgery questionnaires (BMQ/BSQ).Postal questionnaires were completed at participant specific time intervals after joining the trial (equivalent to approximately 3 and 12 months after surgery).Intraoperative data were recorded by the surgeons and all other in-hospital data were collected by the research nurse. At the end of the study period, participants completed a discrete choice experiment questionnaire. Results: The randomised groups were well balanced at entry. Participants had been taking GORD medication for a median of 32 months; the mean age of participants was 46 years and 66% were men. Of 178 randomised to surgery, 111 (62%) actually had fundoplication.There was a mixture of clinical and personal reasons why some patients did not have surgery, sometimes Objectives: To evaluate the clinical effectiveness, costeffectiveness and safety of a policy of relatively early laparoscopic surgery compared with continued medical management amongst people with gastro-oesophageal reflux disease (GORD) judged suitable for both policies. Design: Relative clinical effectiveness was assessed by a randomised trial (with parallel non-randomised preference groups) comparing a laparoscopic surgerybased policy with a continued medical management policy. The economic evaluation compared the costeffectiveness of the two management policies in order to identify the most efficient provision of future care and describe the resource impact that various policies for fundoplication would have on the NHS.Setting: A total of 21 hospitals throughout the UK with a local partnership between surgeon(s) and gastroenterologist(s) who shared the secondary care of patients with GORD.Participants: The 810 participants, who were identified retrospectively or prospectively via their participating clinicians, had both documented evidence of GORD (endoscopy and/or manometry/24-hour pH monitoring) and symptoms for longer than 12 months. In addition,the recruiting clinician(s) was clinically uncertain about which management policy was best.Intervention: Of the 810 eligible patients who consented to participate, 357 were recruited to the related to long waiting times. A total or partial wrap procedure was performed depending on surgeon preference. Complications were uncommon and there were no deaths associated with surgery. By the equivalent of 12 months after surgery, 38% in the randomised surgical group (14% amongst those who had surgery) were taking reflux medication compared with 90% in the randomised medical group. There were substantial differences (one-third to one-half standard deviation) favouring the randomised surgical group across the health status measures, the size depending on assumptions about the proportion that actually had fundoplication. These differences were the same or somewhat smaller than differences observed at 3 months. The lower the reflux score, the worse the symptoms at trial entry and the larger the benefit observed after surgery. The preference surgical group had the lowest reflux scores at baseline. These scores improved substantially after surgery, and by 12 months they were better than those in the preference medical group. The BMQ/BSQ and discrete choice experiment did distinguish the preference groups from each other and from the randomised groups. The latter indicated that the risk of serious complications was the most important single attribute of a treatment option. A within trial cost-effectiveness analysis suggested that the surgery policy was more costly (mean £2049) but also more effective [+0.088 quality-adjusted life-years (QALYs)]. The estimated incremental cost per QALY was £19,000–£23,000, with a probability between 46% (when 62% received surgery) and 19% (when all received surgery) of cost-effectiveness at a threshold of £20,000 per QALY. Modelling plausible longer-term scenarios (such as lifetime benefit after surgery) indicated a greater likelihood (74%) of costeffectiveness at a threshold of £20,000, but applying a range of alternative scenarios indicated wide uncertainty.The expected value of perfect information was greatest for longer-term quality of life and proportions of surgical patients requiring medication.Conclusions: Amongst patients requiring long-term medication to control symptoms of GORD, surgical management significantly increases general and refluxspecific health-related quality of life measures, at least up to 12 months after surgery. Complications of surgery were rare. A surgical policy is, however, more costly than continued medical management. At a threshold of £20,000 per QALY it may well be cost-effective, especially when putative longer-term benefits are taken into account, but this is uncertain.The more troublesome the symptoms, the greater the potential benefit from surgery. Uncertainty about cost-effectiveness would be greatly reduced by more reliable information about relative longer-term costs and benefits of surgical and medical policies. This could be through extended follow-up of the reflux trial cohorts or of other cohorts of fundoplication patients.Peer reviewedPublisher PD

Single port/incision laparoscopic surgery compared with standard three-port laparoscopic surgery for appendicectomy : a randomised controlled trial

PMID: 23111090 [PubMed - indexed for MEDLINE] PMCID: PMC3543288 Free PMC ArticlePeer reviewedPublisher PD

Graphene on quartz modified with rhenium oxide as a semitransparent electrode for organic electronic

Our research shows that commercially available graphene on quartz modified with rhenium oxide meets the requirements for its use as a conductive and transparent anode in optoelectronic devices. The cluster growth of rhenium oxide enables an increase in the work function of graphene by 1.3 eV up to 5.2 eV, which guarantees an appropriate adjustment to the energy levels of the organic semiconductors used in OLED devices.Comment: 8 pages, 3 figure

A historically controlled, single-arm, multi-centre, prospective trial to evaluate the safety and efficacy of MonoMax® suture material for abdominal wall closure after primary midline laparotomy. ISSAAC-Trial [NCT005725079]

<p>Abstract</p> <p>Background</p> <p>Several randomized controlled trials have compared different suture materials and techniques for abdominal wall closure with respect to the incidence of incisional hernias after midline laparotomy and shown that it remains, irrespective of the methods used, considerably high, ranging from 9% to 20%. The development of improved suture materials which would reduce postoperative complications may help to lower its frequency.</p> <p>Design</p> <p>This is a historically controlled, single-arm, multi-centre, prospective trial to evaluate the safety of MonoMax^®suture material for abdominal wall closure in 150 patients with primary elective midline incisions. INSECT patients who underwent abdominal closure using Monoplus^®and PDS^®will serve as historical control group. The incidences of wound infections and of burst abdomen are defined as composite primary endpoints. Secondary endpoints are the frequency of incisional hernias within one year after operation and safety. To ensure adequate comparability in surgical performance and recruitment, the 4 largest centres of the INSECT-Trial will participate. After hospital discharge, the investigators will examine the enrolled patients again at 30 days and at 12 ± 1 months after surgery.</p> <p>Conclusion</p> <p>This historically controlled, single-arm, multi-centre, prospective ISSAAC trial aims to assess whether the use of an ultra-long-lasting absorbable monofilament suture material is safe and efficient.</p> <p>Trial registration</p> <p>NCT005725079</p