(GaAl)As/GaAs heterojunction bipolar transistors with graded composition in the base

The first fabrication and high-speed operation of a three-terminal (AlGa)As/GaAs heterojunction bipolar transistor with graded bandgap base is reported. Cutoff frequencies up to 16 GHz have been achieved in devices fabricated from material made by molecular beam epitaxy. This work demonstrates the feasibility of using a graded (AlGa)As base to enhance the speed of heterojunction bipolar transistors.     

Integral hologram using scanning electron micrographs: a new application of display holography

We produced at 43 times 23 cm, 120° integral hologram of a marine protozoan test to investigate the museum exhibit potential of interfacing scanning electron microscopy with commercially available integral holography. We describe here our procedure and some of the strengths and weaknesses of this holographic medium in exhibit situations.     

Radiobiology of alpha particles. IV. Cell inactivation by alpha particles of energies 0.4-3.5 MeV

In this report the effectiveness of low-energy alpha particles in the range 0.4 to 3.5 MeV for cell killing is investigated. Four cell lines of different nuclear dimensions (AG1522, C3H 10T1/2, CHO-10B, and HS-23) are studied. Monte Carlo simulations are carried out to interpret the experimental results. They are presented as a function of dose to the nucleus, the total track length of alpha particles in the nucleus, and other parameters. It is found that the effectiveness of alpha particles for cell killing decreases with decreasing alpha-particle energy. The maximum RBE value is found to extend to LET values as high as 180 keV/microns. Although the LET might be the same, the effectiveness of alpha particles for cell killing is higher in the ascending part of the Bragg curve compared to descending part of the Bragg curve. The terminal tracks of alpha particles are observed to be less effective for cell killing.     

Comparison of marrow vs blood-derived stem cells for autografting in previously untreated multiple myeloma

Sixty-three new untreated patients with multiple myeloma under the age of 70 years received C-VAMP induction treatment followed by high-dose intravenous melphalan (200 mg m(-2)) and autologous stem cell transplant, either with marrow [autologous bone marrow transplants (ABMT), n = 26] or with granulocyte colony-stimulating factor (G-CSF)-mobilized stem cells from the blood [peripheral blood stem cell transplants (PBSCT), n = 37]. This was a sequential study and the two groups were not significantly different for all known prognostic variables. The complete remission (CR) rate after high-dose treatment was the same for both groups [ABMT 84% and PBSCT 70%; P = not significant (NS)]. Neutrophil recovery to 0.5 x 10(9) l(-1) occurred at a median of 22 days in the ABMT patients compared with 19 days for the PBSCT patients (P = NS). Platelet recovery to 50 x 10(9) l(-1) was significantly faster in PBSCT patients (19 days vs 33 days; P = 0.0015), and the PBSCT patients spent fewer days in hospital (median 20 vs 27 days; P = 0.00001). There was no difference in the two groups with respect to starting interferon (58 days for ABMT vs 55 days for PBSCT), and tolerance to interferon was identical. The median overall survival (OS) and progression-free survival (PFS) for the PBSCT patients has not yet been reached. The OS in the ABMT patients at 3 years was 76.9% (95% CI 60-93%) compared with 85.3% (95% CI 72-99%) in the PBSCT patients (P = NS), and the PFS at 3 years in the ABMT patients was 53.8% (95% CI 34-73%) and in the PBSCT patients was 57.6% (95% CI 34-81%) (P = NS). The probability of relapse at 3 years was 42.3% in the ABMT arm compared with 40% in the PBSCT patients (P = NS). Thus, PBSCT patients had a faster engraftment and a shorter stay in hospital than ABMT; the survival outcome and probability of relapse was the same for both groups.     

Correction to Vogt et al. (2011).

Reports an error in Predeployment, deployment, and postdeployment risk factors for Posttraumatic Stress symptomatology in female and male OEF/OIF veterans by Dawne Vogt, Brian Smith, Rani Elwy, James Martin, Mark Schultz, Mari-Lynn Drainoni and Susan Eisen (Journal of Abnormal Psychology, Advanced Online Publication, Jun 27, 2011, np). In the article there was an error in the affiliation bylines for Rani Elwy and Susan Eisen. Their affiliations should have been listed as Edith Nourse Rogers Memorial Veterans Hospital and Department of Health Policy and Management, Boston University School of Public Health. (The following abstract of the original article appeared in record 2011-13218-001). Prior research on risk factors for posttraumatic stress symptomatology (PTSS) in war-exposed Veterans has revealed both direct and indirect mechanisms of risk that span predeployment, deployment, and postdeployment timeframes. The aims of the present study were to identify the mechanisms through which previously documented risk factors contribute to PTSS in a national sample of 579 female and male Veterans deployed to Afghanistan for Operation Enduring Freedom (OEF) or to Iraq for Operation Iraqi Freedom (OIF), as well as to examine the extent to which results mirror associations observed among Vietnam Veterans (King, King, Foy, Keane, & Fairbank, 1999). Consistent with conservation of resources (COR) theory (Hobfoll, 1989, 2001), findings indicated that PTSS is accounted for by multiple chains of risk, many originating in predeployment experiences that place Veterans at risk for additional stress exposure, and foretell difficulty accessing resources in the face of subsequent stressors. Importantly, the majority of previously documented mechanisms were replicated in this study, suggesting key pathways through which risk factors may contribute to PTSS across different Veteran populations. Results also revealed a number of novel risk mechanisms for OEF/OIF female Veterans, particularly with respect to the role of deployment family relationships in risk for PTSS. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Strain evolution and dopant activation in P-lmplanted metastable pseudomorphic Si(100)/Ge0.12Si0.88

A metastable Ge_0.12Si_0.88 layer 265 nm thick was deposited pseudomorphically on a Si(100) substrate and then implanted with 100 keV phosphorus ions at room temperature for doses of 5 × 10¹³/cm² to 1.5 × 10¹⁵/cm². The ions stop within the epilayer (projected range ∼125 nm). MeV⁴He backscattering/channeling spectrometry, transmission electron microscopy, and double-crystal x-ray diffractometry were used to characterize the damage and strain in the films. The samples were subsequently annealed in high vacuum from 400-800°C for 30 min at each temperature. For the nonamorphized samples (doses of 5 and 10 × 10¹³/cm²), most of the implantation-induced damage and strain disappear after annealing at 400-550°C, but the implanted P ions activate poorly. After annealing at 700-800°C, near complete activation is achieved but the strain relaxes. For the amorphized samples (dose of 1.5 × 10¹⁵/cm²), the amorphous GeSi regrows by solid-phase epitaxy and the dopants are ∼100% activated after annealing at 550°C, but the regrown GeSi relaxes with a high density of dislocations. The strain relaxes more extensively upon annealing in an implanted sample than in a nonimplanted one, other conditions being equal. This effect is more pronounced at higher ion doses, probably due to the increased amount of damage introduced at high doses. On leave from Yonsei University, Seoul 120-749, Korea     

A twin study of smoking, nicotine dependence, and major depression in men.

This study examined the nature of the relationship among lifetime major depression, smoking, and nicotine dependence. Subjects were 8,169 male twins from the Vietnam Era Twin Registry. Biometrical modeling demonstrated a genetic influence on daily smoking, nicotine dependence, and major depression, and a family environmental influence on daily smoking. Genetic factors influencing nicotine dependence also strongly influenced major depression. We also compared probands with a history of major depression (n = 398) from pairs discordant for major depression, their nondepressed cotwins (n = 364), and controls (n = 1,863) on a number of secondary smoking outcomes. Major depression was associated with current daily smoking and certain nicotine withdrawal symptoms. Individuals with a familial vulnerability for major depression, even without a personal history of major depression, were more likely to smoke despite a serious illness and to report nervousness, restlessness, difficulty concentrating, and depressed mood during past quit attempts. Among the 237 monozygotic pairs discordant for major depression, depressed probands were more likely to have a lifetime history of nicotine dependence than were cotwins. Findings extend Kendler and colleague's (1993) study of female twins by demonstrating in men that shared genetic factors predispose not only to major depression and daily smoking but also to major depression and nicotine dependence.     

Regulative interactions in zebrafish neural crest

Zebrafish trunk neural crest cells that migrate at different times have different fates: early-migrating crest cells produce dorsal root ganglion neurons as well as glia and pigment cells, while late-migrating crest cells produce only non-neuronal derivatives. When presumptive early-migrating crest cells were individually transplanted into hosts such that they migrated late, they retained the ability to generate neurons. In contrast, late-migrating crest cells transplanted under the same conditions never generated neurons. These results suggest that, prior to migration, neural crest cells have intrinsic biases in the types of derivatives they will produce. Transplantation of presumptive early-migrating crest cells does not result in production of dorsal root ganglion neurons under all conditions suggesting that these cells require appropriate environmental factors to express these intrinsic biases. When early-migrating crest cells are ablated, late-migrating crest cells gain the ability to produce neurons, even when they migrate on their normal schedule. Interactions among neural crest cells may thus regulate the types of derivatives neural crest cells produce, by establishing or maintaining intrinsic differences between individual cells.     

Depression and multiple sclerosis

The objective of the present study were (1) to ascertain the lifetime risk of a depression in a representative group of multiple sclerosis (MS) patients, (2) to assess the morbidity risks for depression among first-degree relatives of these MS patients, and (3) to compare these familial risks for first-degree relatives of MS patients with those for first-degree relatives of a primary depression population, i.e., depression but no MS. We psychiatrically evaluated 221 MS patients (index cases) using a structured clinical interview for the DSM-III-R and calculated the rate and lifetime risk of depression for these index cases using the product limit estimate of survival function. We obtained psychiatric histories for all first-degree relatives of index cases, and we calculated morbidity risks for depression for these relatives using the maximum likelihood approach and compared the risks using the likelihood ratio tests. Index cases had a 50.3% lifetime risk of depression. Morbidity risks for depression among first-degree relatives of index cases were decidedly lower when compared with morbidity risks among first-degree relatives of the reference population. Although there appears to be a very high rate of depression among MS patients, the data for their first-degree relatives do not support a clear genetic basis for this depression, or at least the same genetic basis that probably operates within families when depression occurs in the absence of MS.