"There should be one spot that you can go:" BRCA mutation carriers' perspectives on cancer risk management and a hereditary cancer registry

Individuals who carry BRCA1 or BRCA2 pathogenic variants are recommended to have extensive cancer prevention screening and risk-reducing surgeries. Uptake of these recommendations is variable, and there remains room for improvement in the risk management of BRCA carriers. This paper explores female BRCA carriers' experiences with the current model of care and their perspectives on (and interest in) an inherited cancer registry. Findings can inform the development of a dedicated high-risk screening and management program for these patients. Quantitative and qualitative data were gathered through a provincial descriptive survey and semi-structured qualitative interviews to assess BRCA carriers' opinions toward risk management services in the province of Newfoundland and Labrador (NL), Canada. Survey (n = 69) and interview data (n = 15) revealed continuity and coordination challenges with the current system of care of high-risk individuals. Respondents suggested an inherited cancer registry would help identify high-risk individuals and provide a centralized system of risk management for identified carriers. Respondents identified concerns about the privacy of their registry data, including who could access it. Findings suggest BRCA carriers see great value in an inherited cancer registry. Specifically, participants noted it could provide a centralized system to help improve the coordination of burdensome, life-long risk management. Important patient concerns about protecting their privacy and their health data confidentiality must be addressed in patient and public information and informed consent documents about a registry.

Tallo: A global tree allometry and crown architecture database

Data capturing multiple axes of tree size and shape, such as a tree's stem diameter, height and crown size, underpin a wide range of ecological research-from developing and testing theory on forest structure and dynamics, to estimating forest carbon stocks and their uncertainties, and integrating remote sensing imagery into forest monitoring programmes. However, these data can be surprisingly hard to come by, particularly for certain regions of the world and for specific taxonomic groups, posing a real barrier to progress in these fields. To overcome this challenge, we developed the Tallo database, a collection of 498,838 georeferenced and taxonomically standardized records of individual trees for which stem diameter, height and/or crown radius have been measured. These data were collected at 61,856 globally distributed sites, spanning all major forested and non-forested biomes. The majority of trees in the database are identified to species (88%), and collectively Tallo includes data for 5163 species distributed across 1453 genera and 187 plant families. The database is publicly archived under a CC-BY 4.0 licence and can be access from: https://doi.org/10.5281/zenodo.6637599. To demonstrate its value, here we present three case studies that highlight how the Tallo database can be used to address a range of theoretical and applied questions in ecology-from testing the predictions of metabolic scaling theory, to exploring the limits of tree allometric plasticity along environmental gradients and modelling global variation in maximum attainable tree height. In doing so, we provide a key resource for field ecologists, remote sensing researchers and the modelling community working together to better understand the role that trees play in regulating the terrestrial carbon cycle.

Audit of waist measurement methods during statutory diving medical assessments

BACKGROUND

Measurement of waist circumference is used to assess abdominal fat and risk of heart disease, type 2 diabetes, cancer and stroke. It is performed in several clinical settings for health promotion and medical assessment purposes, including statutory medical assessments where results may influence decisions on fitness to work. Under the Diving at Work Regulations 1997, working divers must have an annual assessment of their fitness to dive performed by an approved medical examiner of divers (AMED), appointed by the Health and Safety Executive (HSE). The assessment includes measurement of height, weight and waist circumference, the latter used as an indicator of central adiposity and associated health risks.

AIMS

To establish the practice of AMEDs in measuring waist circumference of working divers undergoing medical assessment to determine their fitness to dive.

METHODS

Ninety-seven AMEDs were sent a questionnaire and asked to describe their current practice in measuring waist circumference. The response rate was 79%. The audit standard used was the consensus document published by the World Health Organization (WHO).

RESULTS

Of the 77 responses, 76 were completed sufficiently to allow analysis. When the waist was measured, there was consistency in the diver's level of clothing, stage of breathing and posture for the procedure but variability in the site of measurement. Only 7/76 (9%) respondents carried out waist measurement fully in line with WHO guidance.

CONCLUSIONS

The audit has identified that there is a need for guidance for AMEDs on measuring waist circumference in the statutory medical assessment of working divers.

Moral distress revisited: the viewpoints and responses of nurses

AIM

To present and discuss the main themes that were revealed following an analysis of the qualitative research findings that were extracted from a national survey regarding the causes and effects of moral distress amongst New Zealand nurses.

BACKGROUND/INTRODUCTION

Moral distress continues to be a major concern amongst nurses around the world. In New Zealand, a country where nurses have just been on strike over their working conditions and the deteriorating state of their roles within the health services, it remains a major issue.

METHOD

In the original research project, large numbers of nurses supplied not only quantitative data that revealed the extent and impact of moral distress on their practices, but also extensive notes that more specifically explained the causes and effects of their moral distress. This material has since been thematically analysed and is now presented.

FINDINGS/RESULTS

The data strongly suggested that New Zealand nurses experienced and attempted to respond to several major issues; that is, they were not properly supported by 'the system', frequently experienced problems with managers and bullying, witnessing poor care practices and collegial incompetence, and suffered from ongoing problems caused by moral residue.

CONCLUSION

Under current working conditions, nurses are struggling under an increasing weight of moral residue to maintain their ethical standards within an increasingly difficult ethical climate.

IMPLICATIONS FOR NURSING AND HEALTH POLICY

This research suggests that although nurses clearly seek out and use various ways to cope with moral distress in their practices, there is a continuing need for moral courage and strengthening of moral resilience that involves greater input from not just nurses themselves, but nurse managers, educators and other health services representatives.

Penile Paget's Disease: A Case Report and Review of the Literature

Extramammary Paget's Disease (EMPD) is a rare cutaneous, slow growing, intraepithelial adenocarcinoma that can be either primary (intraepithelial arising within the epidermis) or secondary (intraepithelial spread of a visceral carcinoma). Here we present the case of a 63-year-old male with EMPD of the glans penis stemming from underlying urothelial carcinoma. Our treatment decision elected for management with chemotherapy and local treatment with radiation therapy. Subsequent, review of the literature demonstrated a rare disease with a variety of underlying malignancies causing this secondary pathology. Caregivers should be aware of the association of Paget's disease and urothelial cancer and should have a high index of suspicion that erythematous penile lesions may represent Paget's disease and that penile biopsies should be performed early in this setting.

A cross-sectional analysis of factors associated with the intention to engage in tobacco treatment among inpatients in a state psychiatric hospital

WHAT IS KNOWN ON THE SUBJECT?: People admitted to psychiatric facilities have high rates of tobacco use and hospitalizations present an opportunity for patients to have conversations about tobacco use treatment. Clinicians may believe that people with mental illnesses are not interested in quitting or that they do not understand the importance of treatment. Positive attitudes towards tobacco treatment, viewing that participating in treatment is normal care, and feeling that one is quite able to participate in such treatment predicts intentions to participate in treatment, which, in turn, predicts actual participation. WHAT DOES THIS PAPER ADD TO EXISTING KNOWLEDGE?: Psychiatric patients who use tobacco use report poor prior involvement with tobacco treatment. Positive attitudes towards, encouraging opinions of other people about, and having a sense of control over taking part in tobacco treatment increases plans to engage in treatment. Having a sense of control in taking part in tobacco treatment is strongly associated with prior experiences with evidence-based treatment. WHAT ARE THE IMPLICATIONS FOR PRACTICE?: Because psychiatric hospitalizations are an opportunity for addressing tobacco use and treatment, clinicians should be prepared to support willing patients, especially those with prior substance use histories. Support should include providing them with information regarding tobacco treatment options during their hospital stay and ways that they can continue to receive care after discharge. Clinicians should be promoters of pro-tobacco treatment attitudes and supporting patients' sense of control over participating in treatment during hospitalization.

ABSTRACT

Introduction Hospitalized tobacco users with mental illnesses (MI) may face several barriers to stopping smoking. However, motivational factors that affect the intention to engage in tobacco treatment have been shown to predict actual engagement. Aim To use the Theory of Planned Behavior to assess intentions to and prior experiences of engaging in evidence-based tobacco treatment among hospitalized individuals with MI. Method A cross-sectional survey was conducted among 115 patients in a state psychiatric hospital. Multivariate analyses were used to examine associations with the intentions and prior experiences of engaging in tobacco treatment. Results After controlling for demographic and smoking history, attitudes, subjective norms and perceived behavioural control towards engaging in tobacco treatment were significantly associated with intentions towards treatment engagement. Only higher scores on perceived behavioural control and lower education levels were associated with reported prior experiences of tobacco treatment. Discussion The low prior treatment engagement scores, but relatively higher intention to engage scores among participants suggests the need for deliberate support for evidence-based tobacco treatment during psychiatric hospitalizations. Implications for practice Clinician training in tobacco treatment can promote self-efficacy to engage patients while supporting patients' control so that tobacco treatment is an expected component of psychiatric care.

Allometric equations for integrating remote sensing imagery into forest monitoring programmes

Remote sensing is revolutionizing the way we study forests, and recent technological advances mean we are now able - for the first time - to identify and measure the crown dimensions of individual trees from airborne imagery. Yet to make full use of these data for quantifying forest carbon stocks and dynamics, a new generation of allometric tools which have tree height and crown size at their centre are needed. Here, we compile a global database of 108753 trees for which stem diameter, height and crown diameter have all been measured, including 2395 trees harvested to measure aboveground biomass. Using this database, we develop general allometric models for estimating both the diameter and aboveground biomass of trees from attributes which can be remotely sensed - specifically height and crown diameter. We show that tree height and crown diameter jointly quantify the aboveground biomass of individual trees and find that a single equation predicts stem diameter from these two variables across the world's forests. These new allometric models provide an intuitive way of integrating remote sensing imagery into large-scale forest monitoring programmes and will be of key importance for parameterizing the next generation of dynamic vegetation models.

RADIATION DOSE MEASUREMENTS FOR HIGH-INTENSITY LASER INTERACTIONS WITH SOLID TARGETS AT SLAC

A systematic study of photon and neutron radiation doses generated in high-intensity laser-solid interactions is underway at SLAC National Accelerator Laboratory. These laser-solid experiments are being performed using a 25 TW (up to 1 J in 40 fs) femtosecond pulsed Ti:sapphire laser at the Linac Coherent Light Source's (LCLS) Matter in Extreme Conditions (MEC) facility. Radiation measurements were performed with passive and active detectors deployed at various locations inside and outside the target chamber. Results from radiation dose measurements for laser-solid experiments at SLAC MEC in 2014 with peak intensity between 10¹⁸ and 7.1 × 10¹⁹ W cm^-2 are presented.

Balancing Rights and Duties in ‘Life and Death’ Decision Making Involving Children: a role for nurses?

In recent years, increasing pressures have been brought to bear upon nurses and others more closely to inform, involve and support the rights of parents or guardians when crucial ‘life and death’ ethical decisions are made on behalf of their seriously ill child. Such decisions can be very painful for all involved, and may easily become deadlocked when there is an apparent clash of moral ideals or values between the medical team and the parents or guardians. This article examines a growing number of such cases in New Zealand and analyses the moral parameters, processes, outcomes and ethical responses that must be considered when life and death ethical decisions involving children are made. The article concludes with a recommendation that nurses should be recognized as perhaps the most suitable of all health care personnel when careful mediation is needed to produce an acceptable moral outcome in difficult ethical situations.

Notizen: Characterisation of Pairs of Isomeric Bisaminohexachlorocyclotetraphosphazatetraenes

The isolation of three pairs of isomeric bisaminohexachlorocyclotetraphosphazatetraenes, N4P4Cl6R2 (R = NHBut, NHEt, NMePh) is described. Structures are proposed for the derivatives on the basis of 81P NMR data.

First results from the LUX dark matter experiment at the Sanford underground research facility

The Large Underground Xenon (LUX) experiment is a dual-phase xenon time-projection chamber operating at the Sanford Underground Research Facility (Lead, South Dakota). The LUX cryostat was filled for the first time in the underground laboratory in February 2013. We report results of the first WIMP search data set, taken during the period from April to August 2013, presenting the analysis of 85.3 live days of data with a fiducial volume of 118 kg. A profile-likelihood analysis technique shows our data to be consistent with the background-only hypothesis, allowing 90% confidence limits to be set on spin-independent WIMP-nucleon elastic scattering with a minimum upper limit on the cross section of 7.6 × 10(-46) cm(2) at a WIMP mass of 33 GeV/c(2). We find that the LUX data are in disagreement with low-mass WIMP signal interpretations of the results from several recent direct detection experiments.

Influence of pre-diagnostic cigarette smoking on colorectal cancer survival: overall and by tumour molecular phenotype

BACKGROUND

Smoking is a risk factor for incident colorectal cancer (CRC); however, it is unclear about its influence on survival after CRC diagnosis.

METHODS

A cohort of 706 CRC patients diagnosed from 1999 to 2003 in Newfoundland and Labrador, Canada, was followed for mortality and recurrence until April 2010. Smoking and other relevant data were collected by questionnaire after cancer diagnosis, using a referent period of '2 years before diagnosis' to capture pre-diagnosis information. Molecular analyses of microsatellite instability (MSI) status and BRAF V600E mutation status were performed in tumour tissue using standard techniques. Multivariate hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated with Cox proportional hazards regression, controlling for major prognostic factors.

RESULTS

Compared with never smokers, all-cause mortality (overall survival, OS) was higher for current (HR: 1.78; 95% CI: 1.04-3.06), but not for former (HR: 1.06; 95% CI: 0.71-1.59) smokers. The associations of cigarette smoking with the study outcomes were higher among patients with ≥40 pack-years of smoking (OS: HR: 1.72; 95% CI: 1.03-2.85; disease-free survival (DFS: HR: 1.99; 95% CI: 1.25-3.19), those who smoked ≥30 cigarettes per day (DFS: HR: 1.80; 95% CI: 1.22-2.67), and those with microsatellite stable (MSS) or MSI-low tumours (OS: HR: 1.38; 95% CI: 1.04-1.82 and DFS: HR: 1.32; 95% CI: 1.01-1.72). Potential heterogeneity was noted for sex (DFS HR: 1.68 for men and 1.01 for women: P for heterogeneity=0.04), and age at diagnosis (OS: HR: 1.11 for patients aged <60 and 1.69 for patients aged ≥60: P for heterogeneity=0.03).

CONCLUSIONS

Pre-diagnosis cigarette smoking is associated with worsened prognosis among patients with CRC.

International standardisation work on the measurement of radon in air and water

Radon is considered to be the main source of human exposure to natural radiation. As stated by the World Health Organization, the exposure due to the inhalation of indoor radon is much greater than the one via the ingestion of water as radon degasses from water during handling. In response to these concerns about the universal presence of radon, environmental assessment studies are regularly commissioned to assess the radon exposure of public and workers. The credibility of such studies relies on the quality and reliability of radon analysis as well as on the sample representativeness of the radiological situation. The standard-setting approach, based on consensus, seemed to lend itself to a settlement of technical aspects of potential comparison. At present, two Working Groups of the International Standardization Organization are focussing on drafting standards on radon and its decay products measurement in air and water. These standards, which aim for a set of rigorous metrology practices, will be useful for persons in charge of the initial characterisation of a site with respect to natural radioactivity as well as to those performing the routine surveillance of specific sites.

Investigation of Sidewall Recombination in GaN Using a Quantum Well Probe

In this study, we use a quantum well (QW) probe structure to explore the size dependent effects of sidewall recombination in GaN. Mesas 0.8-7 μm in width with pitches of 4 μm, 8 μm, and 12 μm were etched into the QW probe structure, exposing the QW at the sidewalls. Several etch conditions were investigated. Room temperature photoluminescence (PL) measurements, using a He-Cd laser as an excitation source and laser spot size of approximately 230 μm, were taken before and after the mesas were etched. The effects of sidewall formation were quantified by comparing the maximum PL intensity of the QW before and after etch. Higher remaining PL intensity was observed for etch conditions which used both Ar ions and Cl2 gas instead of only Ar ions. The fraction of remaining PL decreased with decreasing mesa width, however the remaining PL intensity was relatively large even for small features. The preliminary data suggested that GaN is relatively insensitive to sidewall damage.

Antidiabetic effects of duodenojejunal bypass in an experimental model of diabetes induced by a high-fat diet

Background

Obese patients with type II diabetes who undergo bariatric surgery revert to normal blood glucose and insulin levels, and develop a dramatic increase in insulin sensitivity. However, the mechanisms involved are unknown. This study characterized pancreatic islet and duodenojejunal enteroendocrine cells in normal mice and those with diabetes induced by a high-fat diet (HFD) following duodenojejunal bypass (DJB).

Methods

C57BL/6J mice, fed for 8 weeks either a normal diet (n = 10) or a HFD (n = 10) resulting in a hyperglycaemic state, underwent DJB (connection of the distal end of the jejunum to the distal stomach and direction of biliopancreatic secretions to the distal jejunum). Metabolic and immunohistological analyses were carried out on the pancreas and gastrointestinal tract.

Results

A significant decrease in fasting blood glucose was observed in normal-DJB and HFD-DJB mice 1 week after the operation, with improved glucose tolerance at 4 weeks. There were no changes in pancreatic β-cell mass, but an increase in the ratio of α-cell to β-cell mass was observed in the DJB groups. Furthermore, the number of cells expressing Pdx-1, glucagon-like peptide 1, pancreatic polypeptide and synaptophysin was increased in the bypassed duodenum and/or gastrojejunum of the DJB groups.

Conclusion

Both normal and obese diabetic mice that underwent DJB displayed improved glucose tolerance and a reduction in fasting blood glucose, which mimicked findings in obese diabetic patients following bariatric surgery. The present data suggest that an increase in specific enteroendocrine cell populations may play a critical role in normalizing glucose homeostasis.

A comparison of batch effect removal methods for enhancement of prediction performance using MAQC-II microarray gene expression data

Batch effects are the systematic non-biological differences between batches (groups) of samples in microarray experiments due to various causes such as differences in sample preparation and hybridization protocols. Previous work focused mainly on the development of methods for effective batch effects removal. However, their impact on cross-batch prediction performance, which is one of the most important goals in microarray-based applications, has not been addressed. This paper uses a broad selection of data sets from the Microarray Quality Control Phase II (MAQC-II) effort, generated on three microarray platforms with different causes of batch effects to assess the efficacy of their removal. Two data sets from cross-tissue and cross-platform experiments are also included. Of the 120 cases studied using Support vector machines (SVM) and K nearest neighbors (KNN) as classifiers and Matthews correlation coefficient (MCC) as performance metric, we find that Ratio-G, Ratio-A, EJLR, mean-centering and standardization methods perform better or equivalent to no batch effect removal in 89, 85, 83, 79 and 75% of the cases, respectively, suggesting that the application of these methods is generally advisable and ratio-based methods are preferred.

Predictors and outcome associated with an Enterococcus positive isolate during intensive care unit admission

This study reports the incidence, risk factors and mortality associated with a positive Enterococcus spp. isolate during admission to two tertiary intensive care units participating in an antibiotic cycling study. Incidence was low, with only 4.2% of admissions (36/852) at Royal Brisbane and Women's Hospital and 2.8% (31/1104) at Westmead Hospital developing a positive Enterococcus spp. isolate (P=0.087). A positive enterococcal isolate, while not an independent predictor of mortality (odds ratio [OR]=1.6, 95% confidence interval [CI] 0.80 to 3.2, P=0.18), may be a marker of the underlying severity of illness with higher unadjusted in-hospital mortality (26% or 17/66 vs 14% or 250/1855, P=0.007). Independent risk factors for a positive isolate were use of meropenem/imipenem (OR=5.7, 95% CI 2.4 to 14, P <0.001) and cefepime (OR=2.5, 95% CI 1.2 to 5.3, P=0.017) within 48 hours of intensive care unit admission, the presence of a nasogastric tube (OR=4.1, 95% CI 1.3 to 14, P=0.018), renal replacement therapy (OR=2.2, 95% CI 1.0 to 4.7, P=0.046), operative intervention (OR=1.8, 95% CI 1.0 to 3.2, P=0.035) and age (OR=1.2, 95% CI 1.1 to 1.5, P=0.009). None of these factors, except for the need for renal replacement therapy (OR=6.2, 95% CI 1.4 to 27, P=0.015), was associated with increased mortality. Enterococci-directed empiric therapy in the treatment of sepsis remains of unproven value, although this negative finding must be evaluated against other higher powered studies.

Incidence of febrile neutropenia (FN) with pegfilgrastim (PF) on day of chemotherapy (D1) versus 24–72 hrs later (D2)

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Background: Docetaxel, doxorubicin hydrochloride, and cyclophosphamide (TAC) is a commonly used adjuvant chemotherapy (C) regimen in patients (pts) with high risk breast cancer (BC). Pegfilgrastim (PF) is a long acting G-CSF known to decrease the risk of FN. It is typically given the day after C. Illinois CancerCare (ILCC) is a large oncology practice that provides cancer care to many communities in Illinois. For patients with limited access to medical care, in past PF has been given on same day as C. In this study we have compared the incidence of FN in pts who received PF on the same day as TAC (D1) versus those who received it 24–72 hrs after C (D2). Methods: All pts treated for BC at ILCC between 09/2004 and 08/2008, and received TAC and PF were deemed eligible. Logistic regression was used to analyze the association between incidence of FN and type of regimens. Results: Of the 56 eligible pts (55 females), mean age 52.9 yrs (range 27.8–84.8 yrs), 43 patients received PF on D1 and 13 pts received PF on D2. 7 of 43 pts that received PF on D1 developed FN as compared to 1 of 13 pts that received PF on D2. There was a 2.1 times greater probability of developing FN in pts that received PF on D1 versus the pts who received it on D2; 95% CI (0.28–15.6). We did not observe a statistical significance for the above association in univariate analyses or after adjusting for age, stage of disease and receptor status (p>0.05). The lack of significance could be due to small patient population. Conclusions: The odds of developing FN in patients who received PF on the same day as TAC was 2.1 as compared to pts who received it on D2, this difference was statistically not significant.

[Table: see text]

Understanding extraction and beam transport in the ISIS H(-) Penning surface plasma ion source

The ISIS H(-) Penning surface plasma source has been developed to produce beam currents up to 70 mA and pulse lengths up to 1.5 ms at 50 Hz. This paper details the investigation into beam extraction and beam transport in an attempt to understand the beam emittance and to try to improve the emittance. A scintillator profile measurement technique has been developed to assess the performance of different plasma electrode apertures, extraction electrode geometries, and postextraction acceleration configurations. This work shows that the present extraction, beam transport, and postacceleration system are suboptimal and further work is required to improve it.

Acute heart failure in bone marrow transplantation: Impact of intravenous immune globulin as adjuvant therapy

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Background: Little is known regarding management or treatment of cardiac failure after bone marrow transplantation. We investigated the management, treatment and outcome of new onset acute decompensated heart failure (ADHF) after bone marrow transplantation (BMT) with beta blockers, ace-inhibitors and adjuvant intravenous immune globulin (IVIG) therapy. Methods: We retrospectively examined 25 patients with ADHF. Eleven of these patients developed congestive heart failure within 100 days of BMT. Baseline echocardiograms were normal prior to admission and all patients were hospitalized and evaluated for left ventricular ejection fraction (LVEF), and New York Heart Association (NYHA) class. Patients with acute heart failure were treated with standard heart failure medications and patients post-BMT were treated with standard heart failure therapy plus adjuvant (IVIG) (500mg/Kg/day) for 48 hours. Baseline LVEF and NYHA class of 11 patients pre- and post-BMT were compared with LVEF and NYHA class of 14 patients with ADHF that did not receive a BMT. Results: The baseline diagnosis for all patients in the BMT group was NYHA class 4 and post-therapy improved to class 1.2. The baseline diagnosis for all patients in the non-BMT group were NYHA class 3.7 and improved to class 1.2 with medical therapy. The mean LVEF in the BMT group at diagnosis of ADHF was 27.5% and the mean post-therapy with IVIG was 57.6%. The mean baseline LVEF in the group not undergoing BMT and at diagnosis of ADHF was 28.2% and improved post-therapy to 45.2%. Conclusions: Acute decompensated heart failure in the cancer patient is highly treatable with aggressive medical management. Patients with ADHF after BMT and treated with IVIG may have potential clinical benefits with IVIG and standard medical therapy. Significant improvement in LVEF and NYHA were present in the BMT group versus the non-BMT group. These data suggest that BMT outcomes may be improved with routine heart failure management. Further randomized studies should be conducted.

[Table: see text]

No significant financial relationships to disclose.

A Kinetic Model of the Formation of Organic Monolayers on Hydrogen-Terminated Silicon by Hydrosilation of Alkenes

We have analyzed a kinetic model for the formation of organic monolayers based on a previously suggested free radical chain mechanism for the reaction of unsaturated molecules with hydrogen-terminated silicon surfaces (Linford, M. R.; Fenter, P. M.; Chidsey, C. E. D. J. Am. Chem. Soc 1995, 117, 3145). A direct consequence of this mechanism is the nonexponential growth of the monolayer, and this has been observed spectroscopically. In the model, the initiation of silyl radicals on the surface is pseudo first order with rate constant, ki, and the rate of propagation is determined by the concentration of radicals and unreacted Si-H nearest neighbor sites with a rate constant, kp. This propagation step determines the rate at which the monolayer forms by addition of alkene molecules to form a track of molecules that constitute a self-avoiding random walk on the surface. The initiation step describes how frequently new random walks commence. A termination step by which the radicals are destroyed is also included. The solution of the kinetic equations yields the fraction of alkylated surface sites and the mean length of the random walks as a function of time. In mean-field approximation we show that (1) the average length of the random walk is proportional to (kp/ki)1/2, (2) the monolayer surface coverage grows exponentially only after an induction period, (3) the effective first-order rate constant describing the growth of the monolayer and the induction period (kt) is k = (2ki kp)1/2, (4) at long times the effective first-order rate constant drops to ki, and (5) the overall activation energy for the growth kinetics is the mean of the activation energies for the initiation and propagation steps. Monte Carlo simulations of the mechanism produce qualitatively similar kinetic plots, but the mean random walk length (and effective rate constant) is overestimated by the mean field approximation and when kp >> ki, we find k approximately ki0.7kp0.3 and Ea = (0.7Ei+ 0.3Ep). However the most striking prediction of the Monte Carlo simulations is that at long times, t >> 1/k, the effective first-order rate constant decreases to ki even in the absence of a chemical termination step. Experimental kinetic data for the reaction of undec-1-ene with hydrogen-terminated porous silicon under thermal reflux in toluene and ethylbenzene gave a value of k = 0.06 min(-1) and an activation energy of 107 kJ mol(-1). The activation energy is in reasonable agreement with density functional calculations of the transition state energies for the initiation and propagation steps.

Precision measurement of the weak mixing angle in Møller scattering

We report on a precision measurement of the parity-violating asymmetry in fixed target electron-electron (Møller) scattering: A(PV) = [-131 +/- 14(stat) +/- 10(syst)] x 10(-9), leading to the determination of the weak mixing angle sin2(thetaW(eff) = 0.2397 +/- 0.0010(stat) +/- 0.0008(syst), evaluated at Q2 = 0.026 GeV2. Combining this result with the measurements of sin2(thetaW(eff) at the Z0 pole, the running of the weak mixing angle is observed with over 6sigma significance. The measurement sets constraints on new physics effects at the TeV scale.

Direct measurements of Ab and Ac using vertex and kaon charge tags at the SLAC detector

Exploiting the manipulation of the SLAC Linear Collider electron-beam polarization, we present precise direct measurements of the parity-violation parameters A(c) and A(b) in the Z-boson-c-quark and Z-boson-b-quark coupling. Quark-antiquark discrimination is accomplished via a unique algorithm that takes advantage of the precise SLAC Large Detector charge coupled device vertex detector, employing the net charge of displaced vertices as well as the charge of kaons that emanate from those vertices. From the 1996-1998 sample of 400 000 Z decays, produced with an average beam polarization of 73.4%, we find A(c)=0.673+/-0.029(stat)+/-0.023(syst) and A(b)=0.919+/-0.018(stat)+/-0.017(syst).

Observation of parity nonconservation in møller scattering

We report a measurement of the parity-violating asymmetry in fixed target electron-electron (Møller) scattering: A(PV)=[-175+/-30(stat)+/-20(syst)] x 10(-9). This first direct observation of parity nonconservation in Møller scattering leads to a measurement of the electron's weak charge at low energy Q(e)(W)=-0.053+/-0.011. This is consistent with the standard model expectation at the current level of precision: sin((2)theta(W)(M(Z))((-)MS)=0.2293+/-0.0024(stat)+/-0.0016(syst)+/-0.0006(theory).

Improved direct measurement of the parity-violation parameter Ab using a mass tag and momentum-weighted track charge

We present an improved direct measurement of the parity-violation parameter A(b) in the Z boson-b-quark coupling using a self-calibrating track-charge technique applied to a sample enriched in Z-->bb events via the topological reconstruction of the B hadron mass. Manipulation of the Stanford Linear Collider electron-beam polarization permits the measurement of A(b) to be made independently of other Z-pole coupling parameters. From the 1996-1998 sample of 400,000 hadronic Z decays, produced with an average beam polarization of 73.4%, we find A(b)=0.906+/-0.022(stat)+/-0.023(syst).

Intra-alveolar distraction osteogenesis in preparation for dental implant placement combined with orthodontic/orthognathic surgical treatment: A case report

The use of implants has become a routine part of restorative dental treatment. The placement of implants requires a sufficient quantity of bone in which to place implant fixtures. Where such bone does not exist, a number of methods have been used to augment the affected area of the alveolar ridge. This case report describes the use of the relatively new distraction osteogenesis procedure to increase bone volume in a patient who required post-traumatic restoration of several missing teeth, as well as comprehensive orthodontic and orthognathic surgical treatment.