Is manganese-doped diamond a ferromagnetic semiconductor?

We use density-functional theoretical methods to examine the recent prediction, based on a mean-field solution of the Zener model, that diamond doped by Mn (with spin S=5/2) would be a dilute magnetic semiconductor that remains ferromagnetic well above room temperature. Our findings suggest this to be unlikely, for four reasons: (1) substitutional Mn in diamond has a low-spin S=1/2 ground state; (2) the substitutional site is energetically unfavorable relative to the much larger "divacancy" site; 3) Mn in the divacancy site is an acceptor, but with only hyperdeep levels, and hence the holes are likely to remain localized; (4) the calculated Heisenberg couplings between Mn in nearby divacancy sites are two orders of magnitude smaller than for substitutional Mn in germanium.Comment: 5 pages, 5 figure

Search for first-generation scalar and vector leptoquarks

We describe a search for the pair production of first-generation scalar and vector leptoquarks in the eejj and enujj channels by the D0 Collaboration. The data are from the 1992--1996 ppbar run at sqrt{s} = 1.8 TeV at the Fermilab Tevatron collider. We find no evidence for leptoquark production; in addition, no kinematically interesting events are observed using relaxed selection criteria. The results from the eejj and enujj channels are combined with those from a previous D0 analysis of the nunujj channel to obtain 95% confidence level (C.L.) upper limits on the leptoquark pair-production cross section as a function of mass and of beta, the branching fraction to a charged lepton. These limits are compared to next-to-leading-order theory to set 95% C.L. lower limits on the mass of a first-generation scalar leptoquark of 225, 204, and 79 GeV/c^2 for beta=1, 1/2, and 0, respectively. For vector leptoquarks with gauge (Yang-Mills) couplings, 95% C.L. lower limits of 345, 337, and 206 GeV/c^2 are set on the mass for beta=1, 1/2, and 0, respectively. Mass limits for vector leptoquarks are also set for anomalous vector couplings

Hard Single Diffraction in pbarp Collisions at root-s = 630 and 1800 GeV

Using the D0 detector, we have studied events produced in proton-antiproton collisions that contain large forward regions with very little energy deposition (``rapidity gaps'') and concurrent jet production at center-of-mass energies of root-s = 630 and 1800 Gev. The fractions of forward and central jet events associated with such rapidity gaps are measured and compared to predictions from Monte Carlo models. For hard diffractive candidate events, we use the calorimeter to extract the fractional momentum loss of the scattered protons.Comment: 11 pages 4 figures. submitted to PR

New insights into the genetic etiology of Alzheimer's disease and related dementias

Characterization of the genetic landscape of Alzheimer's disease (AD) and related dementias (ADD) provides a unique opportunity for a better understanding of the associated pathophysiological processes. We performed a two-stage genome-wide association study totaling 111,326 clinically diagnosed/'proxy' AD cases and 677,663 controls. We found 75 risk loci, of which 42 were new at the time of analysis. Pathway enrichment analyses confirmed the involvement of amyloid/tau pathways and highlighted microglia implication. Gene prioritization in the new loci identified 31 genes that were suggestive of new genetically associated processes, including the tumor necrosis factor alpha pathway through the linear ubiquitin chain assembly complex. We also built a new genetic risk score associated with the risk of future AD/dementia or progression from mild cognitive impairment to AD/dementia. The improvement in prediction led to a 1.6- to 1.9-fold increase in AD risk from the lowest to the highest decile, in addition to effects of age and the APOE ε4 allele

Chemotherapy in Recurrent Advanced Non-Small-Cell Lung Cancer After Adjuvant Chemotherapy

Introduction: Despite adjuvant systemic therapy in patients with completely resected non-small-cell lung cancer (NSCLC), many will subsequently relapse. We investigated treatment choices at relapse and assessed the effect of palliative platinum doublet systemic therapy in this population. Methods: With research ethics board approval, we performed a retrospective chart review of all patients with resected NSCLC who received adjuvant systemic therapy from January 2002 until December 2008 at our institution. The primary outcome was the response rate to first-line palliative systemic therapy among patients who relapsed. Results: We identified 176 patients who received adjuvant platinum doublet systemic therapy (82% received cisplatin–vinorelbine). In the 85 patients who relapsed (48%), median time to relapse was 18.5 months (95% confidence interval: 15 months to 21.3 months). Palliative systemic therapy was given in 43 patients. Of those 43 patients, 25 (58%) were re-challenged with platinum doublet systemic therapy, with a response rate of 29% compared with 18% in 18 patients who received other systemic therapy (p = 0.48). We observed a trend toward an increased clinical benefit rate (complete response + partial response + stable disease) in patients who were treated with a platinum doublet (67% vs. 41%, p = 0.12). Median overall survival (OS) from relapse was 15.3 months in patients receiving palliative systemic therapy and 7.8 months in those receiving best supportive care alone. Compared with patients treated with non-platinum regimens, the platinum-treated group experienced longer survival after relapse (18.4 months vs. 9.7 months, p = 0.041). Conclusions: In patients previously treated with adjuvant systemic therapy, re-treatment with platinum doublet chemotherapy upon relapse is feasible. Moreover, compared with patients receiving other first-line systemic therapy, patients receiving platinum doublets experienced higher response rates and significantly longer survival

Are Clinical Trial Eligibility Criteria an Accurate Reflection of a Real-World Population of Advanced Non-Small-Cell Lung Cancer Patients?

Background: Advanced non-small-cell lung cancer (NSCLC) represents a major health issue globally. Systemic treatment decisions are informed by clinical trials, which, over years, have improved the survival of patients with advanced NSCLC. The applicability of clinical trial results to the broad lung cancer population is unclear because strict eligibility criteria in trials generally select for optimal patients. Methods: We performed a retrospective chart review of all consecutive patients with advanced NSCLC seen in outpatient consultation at our academic institution between September 2009 and September 2012, collecting data about patient demographics and cancer characteristics, treatment, and survival from hospital and pharmacy records. Two sets of arbitrary trial eligibility criteria were applied to the cohort. Scenario A stipulated Eastern Cooperative Oncology Group performance status (ECOG PS) 0–1, no brain metastasis, creatinine less than 120 μmol/L, and no second malignancy. Less-strict scenario B stipulated ECOG PS 0–2 and creatinine less than 120 μmol/L. We then used the two scenarios to analyze treatment and survival of patients by trial eligibility status. Results: The 528 included patients had a median age of 67 years, with 55% being men and 58% having adenocarcinoma. Of those 528 patients, 291 received at least 1 line of palliative systemic therapy. Using the scenario A eligibility criteria, 73% were trial-ineligible. However, 46% of “ineligible” patients actually received therapy and experienced survival similar to that of the “eligible” treated patients (10.2 months vs. 11.6 months, p = 0.10). Using the scenario B criteria, only 35% were ineligible, but again, the survival of treated patients was similar in the ineligible and eligible groups (10.1 months vs. 10.9 months, p = 0.57). Conclusions: Current trial eligibility criteria are often strict and limit the enrolment of patients in clinical trials. Our results suggest that, depending on the chosen drug, its toxicities and tolerability, eligibility criteria could be carefully reviewed and relaxed