Effect of aluminum on the low temperature properties of relatively high purity ferrite

True stress-strain data on alloys of pure iron with up to 2.4 pct Al were obtained in the temperature range +100° to ?185°C. Aluminum was found to reduce yield and flow stresses of iron at low temperatures but to have little or no effect on ductility. The effects of temperature and composition on strain hardening are discussed.     

The lesbian,gay, bisexual and transgender community online: discussions of bullying and self-disclosure in YouTube videos

Computer-mediated communication has become a popular platform for identity construction and experimentation as well as social interaction for those who identify as lesbian, gay, bisexual or transgender (LGBT). The creation of user-generated videos has allowed content creators to share experiences on LGBT topics. With bullying becoming more common amongst LGBT youth, it is important to obtain a greater understanding of this phenomenon. In our study, we report on the analysis of 151 YouTube videos which were identified as having LGBT- and bullying-related content. The analysis reveals how content creators openly disclose personal information about themselves and their experiences in a non-anonymous rhetoric with an unknown public. These disclosures could indicate a desire to seek friendship, support and provide empathy.     

A gain and bandwidth enhanced transimpedance preamplifier for Fourier-transform ion cyclotron resonance mass spectrometry

The nature of the ion signal from a 12-T Fourier-transform ion cyclotron resonance mass spectrometer and the electronic noise were studied to further understand the electronic detection limit. At minimal cost, a new transimpedance preamplifier was designed, computer simulated, built, and tested. The preamplifier design pushes the electronic signal-to-noise performance at room temperature to the limit, because of its enhanced tolerance of the capacitance of the detection device, lower intrinsic noise, and larger flat mid-band gain (input current noise spectral density of around 1 pA/√Hz when the transimpedance is about 85 dBΩ). The designed preamplifier has a bandwidth of ~3 kHz to 10 MHz, which corresponds to the mass-to-charge ratio, m/z, of approximately 18 to 61 k at 12 T. The transimpedance and the bandwidth can be easily adjusted by changing the value of passive components. The feedback limitation of the circuit is discussed. With the maximum possible transimpedance of 5.3 MΩ when using an 0402 surface mount resistor, the preamplifier was estimated to be able to detect ~110 charges in a single scan.     

Isolation of yeast artificial chromosomes free of endogenous yeast chromosomes: construction of alternate hosts with defined karyotypic alterations

An intrinsic feature of yeast artificial chromosomes (YACs) is that the cloned DNA is generally in the same size range (i.e., approximately 200-2000 kb) as the endogenous yeast chromosomes. As a result, the isolation of YAC DNA, which typically involves separation by pulsed-field gel electrophoresis, is frequently confounded by the presence of a comigrating or closely migrating endogenous yeast chromosome(s). We have developed a strategy that reliably allows the isolation of any YAC free of endogenous yeast chromosomes. Using recombination-mediated chromosome fragmentation, a set of Saccharomyces cerevisiae host strains was systematically constructed. Each strain contains defined alterations in its electrophoretic karyotype, which provide a large-size interval devoid of endogenous chromosomes (i.e., a karyotypic "window"). All of the constructed strains contain the kar1-delta 15 mutation, thereby allowing the efficient transfer of a YAC from its original host into an appropriately selected window strain using the kar1-transfer procedure. This approach provides a robust and efficient means to obtain relatively pure YAC DNA regardless of YAC size.     

Challenges in Liquid‐Phase Exfoliation,Processing, and Assembly of Pristine Graphene

Recent developments in the exfoliation, dispersion, and processing of pristine graphene (i.e., non‐oxidized graphene) are described. General metrics are outlined that can be used to assess the quality and processability of various “graphene” products, as well as metrics that determine the potential for industrial scale‐up. The pristine graphene production process is categorized from a chemical engineering point of view with three key steps: i) pretreatment, ii) exfoliation, and iii) separation. How pristine graphene colloidal stability is distinct from the exfoliation step and is dependent upon graphene interactions with solvents and dispersants are extensively reviewed. Finally, the challenges and opportunities of using pristine graphene as nanofillers in polymer composites, as well as as building blocks for macrostructure assemblies are summarized in the context of large‐scale production.     

Prevalence and incidence of hand dermatitis in hairdressing apprentices: results of the POSH study. Prevention of occupational skin disease in hairdressers

OBJECTIVE: Occupational skin changes in hairdressers are very common. Morbidity, however, has not yet been quantified precisely. METHODS: A cohort of 2,352 hairdressing apprentices (of the 2,570 invited to participate, i.e., 91.5% response) was prospectively followed for the duration of their vocational training (3 years) by three examinations. Three waves (years) were recruited in 1992, 1993, and 1994 from 15 vocational training schools in northwestern Germany. RESULTS: The point prevalence of (mostly slight) irritant skin changes of the hands increased from 35.4% in the initial examination to 47.5% in the intermediate examination and to 55.1% in the final examination. Given a more conservative definition of a case of "hand dermatitis," these estimates were 12.9%, 23.5%, and 23.9%, respectively. Altogether, 34.3 and 15.2 cases of "skin changes (any degree)" and "hand dermatitis," respectively, in 100 person-years were observed during the study period. The incidence rate, i.e., the number of newly diseased study participants in relation to the person-time at risk contributed, decreased in the course of the study. The proportion of dropouts until final follow-up was 51.8%. CONCLUSION: The present results appear to lie in a range with those found in other, much smaller cohort studies. However, comparison of the results is hampered either by the lack of a clear definition or by a different definition of "person-time at risk" or "a case of hand dermatitis." As compared with an external control group of office apprentices, the incidence was several times higher in hairdressing apprentices, which points to the high risk for skin damage in this occupation.     

Assessing patients'' priorities and perceptions of the quality of health care: the development of the QUOTE-Rheumatic-Patients instrument

BACKGROUND: Stress can exacerbate a number of psychiatric disorders, many of which are associated with prefrontal cortical (PFC) cognitive deficits. Biochemical studies demonstrate that mild stress preferentially increases dopamine turnover in the PFC. Our study examined the effects of acute, mild stress exposure on higher cognitive function in monkeys and the role of dopaminergic mechanisms in the stress response. METHODS: The effects of loud (105-dB) noise stress were examined on a spatial working memory task (delayed response) dependent on the PFC, and on a reference memory task with similar motor and motivational demands (visual pattern discrimination) dependent on the inferior temporal cortex. The role of dopamine mechanisms was tested by challenging the stress response with agents that decrease dopamine receptor stimulation. RESULTS: Exposure to noise stress significantly impaired delayed-response performance. Stress did not impair performance on "0-second" delay control trials and did not alter visual pattern discrimination performance, which is consistent with impaired PFC cognitive function rather than nonspecific changes in performance. Stress-induced deficits in delayed-response performance were ameliorated by pretreatment with drugs that block dopamine receptors (haloperidol, SCH 23390) or reduce stress-induced PFC dopamine turnover in rodents (clonidine, naloxone hydrochloride). CONCLUSIONS: These results indicate that stress impairs PFC cognitive function through a hyperdopaminergic mechanism. Stress may take the PFC "off-line" to allow more habitual responses mediated by posterior cortical and subcortical structures to regulate behavior. This mechanism may have survival value, but may often be maladaptive in human society, contributing to the vulnerability of the PFC in many neuropsychiatric disorders.     

FRC measurement in intensive care patients. A definition of standards

Determination of Functional Residual Capacity (FRC) can be performed through washout methods, indicator gas dilution or bodyplethysmography. Some of these techniques have been adapted for use in intensive care patients whilst being mechanically ventilated. However, most measurement setups are bulky, cumbersome to use and their running costs are high. Hence FRC measurement has not become a routine method in intensive care although it offers considerable advantages in the management of ventilated patients such as the determination of "best PEEP", the detection of progressive alveolar collapse in the course of acute lung injury and during weaning from mechanical ventilation. Up to now most efforts to improve and simplify FRC measurement were made at the expense of accuracy. An ideal method ought to be accurate, easy to handle and cost-effective. It should supply not only FRC data but also information about intrapulmonary gas distribution and dead space. These demands can be met using modern data acquisition software. The pros and cons of all methods available for FRC measurement are discussed in view of their suitability for intensive care patients. A conventional nitrogen washout using emission spectroscopy for measurement of nitrogen concentration gives satisfying exact values for the determination of the parameters mentioned above. The measurement error can be lowered under 5% by special corrections for flow and nitrogen signal (delay and rise times, changes of gas viscosity). For flow measurement a normal pneumotachograph can be used. Using a laptop computer for data acquisition the bed-side monitor fulfills most of the demands in intensive care. It is then also possible to measure indices of intrapulmonary gas distribution such as Alveolar Mixing Efficiency and Lung Clearance Index.