Measurement of carrier transport and recombination parameter in heavily doped silicon

The minority carrier transport and recombination parameters in heavily doped bulk silicon were measured. Both Si:P and Si:B with bulk dopings from 10 to the 17th and 10 to the 20th power/cu cm were studied. It is shown that three parameters characterize transport in bulk heavily doped Si: the minority carrier lifetime tau, the minority carrier mobility mu, and the equilibrium minority carrier density of n sub 0 and p sub 0 (in p-type and n-type Si respectively.) However, dc current-voltage measurements can never measure all three of these parameters, and some ac or time-transient experiment is required to obtain the values of these parameters as a function of dopant density. Using both dc electrical measurements on bipolar transitors with heavily doped base regions and transients optical measurements on heavily doped bulk and epitaxially grown samples, lifetime, mobility, and bandgap narrowing were measured as a function of both p and n type dopant densities. Best fits of minority carrier mobility, bandgap narrowing and lifetime as a function of doping density (in the heavily doped range) were constructed to allow accurate modeling of minority carrier transport in heavily doped Si

Heavy-Quark Hybrid Mass Splittings: Hyperfine and "Ultrafine"

It is argued that the heavy-quark limit of QCD requires a certain combination of hyperfine mass splittings in heavy-quark hybrid-meson multiplets to be unusually small. This observation will assist in the exploration of the heavy-quark hybrid spectrum at facilities such as PANDA. Alternatively, a large measured value for this mass splitting indicates that at least one member of the multiplet must contain significant light-quark degrees of freedom.Comment: Version to appear in Few-Body Systems. Substantial modifications from previous version, including extensive additional references and an expanded discussion of relevant operators. 7 page

Duty Performance of Vocational Guidance Counselors

It appeared to the author from reviewing the proposed Washington State Standards that perhaps the quality and guidance functions recommended by the Panel and adopted by the Vocational Education Act, to be available to students, were not being met by the counselors qualifying under the variety of requirements available to Washington State counselors. More specifically, it appeared that counselors being certified under a particular set of requirements would tend to perform a particular stage of counseling more successfully due to the experiences required for certification. The problem as viewed by the author is that the variety of criteria available for certification overshadows the efficacy of a single certificate. It appeared that fulfillment of one set of requirements does not imply success in all stages of counseling

Environment assisted degradation mechanisms in advanced light metals

The general goals of the research program are to characterize alloy behavior quantitatively and to develop predictive mechanisms for environmental failure modes. Successes in this regard will provide the basis for metallurgical optimization of alloy performance, for chemical control of aggressive environments, and for engineering life prediction with damage tolerance and long term reliability

Conrad Specialty Roofing

I know it’s hard to believe, Allen, but Max is dying,” said Bill Levis, as he paced about the cramped, dingy office of Conrad Specialty Roofing (CSR). “He and I were partners for 15 years and friends for a lot longer than that. Mary and his kids are devastated; hell, he’s only 50 years old. I don’t know how she’s going to get through this – you know what kind of person she is.”Yes, I know what kind of person she is, thought Allen. She’s worked in this office for the past four years, if you could describe what she did as work. In addition to successfully building CSR for the past five years, Max had always taken care of Mary and the children, made even the smallest decisions for them. And now he’s going to be leaving them on their own… He’s going to be leaving me on my own, too, Allen’s thoughts continued. “ This certainly explains Max’s odd behavior over the last few months” said Allen, shaking his head.  “He’s pretty much put me in charge of everything lately – sales, supervision, ordering material, paying bills, the works. He hired me last year as a project manager, but he’s been around here so little I feel like the owner.”                 “That’s good,” replied Bill, “because it looks like you are going to be the owner. When I saw Max yesterday, he told me how proud he was of the way you took up the slack and kept the business going smoothly over the past six months. He told me that he wanted you to own CSR and was going to see his lawyer to put something about it in his will. I agreed with him, possibly for the first time since we split up our partnership five years ago; you have really been a lifesaver for this business – without you, it would have been doomed, just like Max… You are CSR, you know.”                 “Now all we need to do is arrange something equitable with Mary,” continued Bill. “I’ve known her so long… perhaps I can help.

Illness Beliefs and Walking Behavior After Revascularization for Intermittent Claudication: A Qualitative Study

PURPOSE: Patients with peripheral artery disease (PAD) are recommended to increase physical activity to reduce cardiovascular risk. Vascular intervention (surgery or angioplasty) treats the symptom (intermittent claudication), but not the underlying cardiovascular disease. This study aims to explore the beliefs and physical activity behavior of patients with PAD who have received vascular intervention. METHODS: Twenty participants who had received a vascular intervention for intermittent claudication between 6 months and 2 years previously participated in semistructured interviews. The interviews explored illness and treatment beliefs and walking behavior. Data were transcribed verbatim and analyzed thematically. RESULTS: Participants described a high level of ongoing symptoms (particularly pain) in their legs, despite having received vascular intervention. They viewed their illness as acute and treatable, and believed that pain was an indication of walking causing damage. They controlled their symptoms by avoiding walking and slowing their pace. Participants were generally unaware of the causes of the disease and were unaware of their increased risk of future cardiovascular health problems. There was a low level of congruence between participant beliefs about their illness and the recommendation to increase physical activity that may affect physical activity behavior. CONCLUSIONS: Our findings suggest that patients with PAD do not change physical activity behavior after diagnosis and treatment, because they hold dysfunctional and incongruous beliefs about PAD, treatment, and physical activity

Pilot Safety Evaluation of Varenicline for the Treatment of Methamphetamine Dependence.

Despite the worldwide extent of methamphetamine dependence, no medication has been shown to effectively treat afflicted individuals. One relatively unexplored approach is modulation of cholinergic system function. Animal research suggests that enhancement of central cholinergic activity, possibly at nicotinic acetylcholine receptors (nAChRs), can reduce methamphetamine-related behaviors. Further, preliminary findings indicate that rivastigmine, a cholinesterase inhibitor, may reduce craving for methamphetamine after administration of the drug in human subjects. We therefore performed a double-blind, placebo-controlled, crossover pilot study of the safety and tolerability of varenicline in eight methamphetamine-dependent research subjects. Varenicline is used clinically to aid smoking cessation, and acts as a partial agonist at α4β2 nAChRs with full agonist properties at α7 nAChRs. Oral varenicline dose was titrated over 1 week to reach 1 mg bid, and then was co-administered with 30 mg methamphetamine, delivered in ten intravenous infusions of 3 mg each. Varenicline was found to be safe in combination with IV methamphetamine, producing no cardiac rhythm disturbances or alterations in vital sign parameters. No adverse neuropsychiatric sequelae were detected either during varenicline titration or following administration of methamphetamine. The results suggest that varenicline warrants further investigation as a potential treatment for methamphetamine dependence