Female voice communications in high levels of aircraft cockpit noises--Part I: spectra, levels, and microphones

HYPOTHESIS: Female produced speech, although more intelligible than male speech in some noise spectra, may be more vulnerable to degradation by high levels of some military aircraft cockpit noises. The acoustic features of female speech are higher in frequency, lower in power, and appear more susceptible than male speech to masking by some of these military noises. Current military aircraft voice communication systems were optimized for the male voice and may not adequately accommodate the female voice in these high level noises. METHODS: This applied study investigated the intelligibility of female and male speech produced in the noise spectra of four military aircraft cockpits at levels ranging from 95 dB to 115 dB. The experimental subjects used standard flight helmets and headsets, noise-canceling microphones, and military aircraft voice communications systems during the measurements. RESULTS: The intelligibility of female speech was lower than that of male speech for all experimental conditions; however, differences were small and insignificant except at the highest levels of the cockpit noises. Intelligibility for both genders varied with aircraft noise spectrum and level. Speech intelligibility of both genders was acceptable during normal cruise noises of all four aircraft, but improvements are required in the higher levels of noise created during aircraft maximum operating conditions. CONCLUSIONS: The intelligibility of female speech was unacceptable at the highest measured noise level of 115 dB and may constitute a problem for other military aviators. The intelligibility degradation due to the noise can be neutralized by use of an available, improved noise-canceling microphone, by the application of current active noise reduction technology to the personal communication equipment, and by the development of a voice communications system to accommodate the speech produced by both female and male aviators.     

Concordance of self- and informant ratings of adults' current and childhood attention-deficit/hyperactivity disorder symptoms.

Self-informant rating concordance for attention-deficit/hyperactivity disorder (ADHD) symptoms was assessed in 281 adults at the subscale (Inattention, Hyperactivity-Impulsivity) and individual symptom levels. Potential demographic, diagnostic, and informant identity moderators were also investigated. Concordance levels were similar for current and childhood symptoms. Although moderate positive correlations were found between self- and informant ratings on both subscales, informants endorsed more significant inattentive symptom severity. Kappa coefficients were variable, suggesting low concordance for certain symptoms. Sex and ADHD diagnosis moderated concordance, although effect sizes were small. These results have implications for the use of behavior rating scales in diagnosing ADHD, raise questions about the validity of self- and informant ratings, and support the need to investigate individual differences variables that may impact concordance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

College-educated women's personality development in adulthood: Perceptions and age differences.

Adulthood encompasses a large time span and includes a series of psychosocial challenges (E. H. Erikson, 1950). Five aspects of personality (identity certainty, confident power, concern with aging, generativity, and personal distress) were assessed in a cross-sectional study of college-educated women who at the time of data collection were young adults (age: M = 26 years), middle-aged adults (age: M = 46 years), or older adults (age: M = 66 years). Respondents rated each personality domain for how true it was of them at the time, and they then rated the other 2 ages either retrospectively or prospectively. Results are discussed with attention to the ways in which women's adult development may have been shaped by experiences particular to both gender and birth cohort, and to how these women fit with E. H. Erikson's theory of adult development. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Electrophoretic behavior and size distribution of the acidic polysaccharides produced by the bacteria Bradyrhizobium (Chamaecytisus) strain BGA-1 and Bradyrhizobium japonicum USDA 110

The electrophoretic behavior in polyacrylamide gels of the acidic polysaccharides produced by the soil bacteria Bradyrhizobium (Chamaecytisus) strain BGA1 and Bradyrhizobiumjaponicum USDA1 10 has been studied. Both polysaccharides were polydisperse, producing a ladder-like pattern after fixation with Alcian Blue and silver staining of the gel. The polysaccharide molecules were separated according to their size, and they behaved as a collection of flexible random coils of different size and similar charge/mass ratio. The electrophoretic behavior was not affected by the presence of acetyl groups in the polysaccharide. The range of molecular weights of the exopolysaccharide produced by B. japonicum USDA110 was wider and with larger molecules than that of the polysaccharide produced by strain BGA1. The resolution was dependent on the electrophoresis buffer; the best results were achieved with Tris-borate; in Tris-glycine buffer, the resolution was worse, and it was not improved by the addition of sodium dodecyl sulfate (SDS).     

Regionalized lipid diffusion in the plasma membrane of mammalian spermatozoa

The plasma membrane of mammalian spermatozoa shows pronounced lateral asymmetry with many glycoproteins restricted to specific domains. Some of these antigens are freely diffusing throughout the membrane whereas others appear static in position. It is not clear whether these concepts also apply to membrane lipids. In this investigation we have used fluorescence recovery after photobleaching (FRAP) techniques to spatially resolve lipid dynamics in various surface domains of 5 species of mammalian spermatozoa (bull, boar, ram, mouse, and guinea pig). Sperm plasma membranes were loaded with 5-(N-octadecanoyl)aminofluorescein (ODAF) reporter probe, and its diffusion was measured in various domains by FRAP analysis. Results showed that in live bull, boar, ram, and mouse spermatozoa, diffusion coefficients (D) were significantly higher over the acrosome and postacrosome than on the midpiece and principal piece of the tail. In dead or permeabilized cells, on the other hand, large immobile phases developed, particularly on the sperm tail, that severely reduced D values. ODAF diffusion was also sensitive to temperature and cross-linking of protein components within the membrane with paraformaldehyde. Guinea pig spermatozoa were different in almost all respects from those of the other species tested. It is concluded that lipid diffusion in the plasma membrane of live spermatozoa varies significantly between surface domains, because of either compositional heterogeneity, or differences in bilayer disposition, or the presence of intramembranous barriers that impede free exchange between domains. This study emphasizes the important role of membrane lipids in regulating polarized migration of sperm surface antigens during developmental processes such as maturation and capacitation.     

Prevalence and risk factors for diabetic retinopathy in the multiethnic population of Mauritius

This study examines the prevalence of, and risk factors for, diabetic retinopathy in Asian Indian, Chinese, and Creole Mauritians in whom there is an increasing prevalence of non-insulin-dependent diabetes mellitus (NIDDM). As part of a population-based survey on the Indian Ocean island of Mauritius in 1992, glucose tolerance was classified using a 75-g oral glucose tolerance test on 6,553 persons. Subjects with newly diagnosed (n = 358) or known diabetes (n = 388), and a random sample of one in four subjects with impaired glucose tolerance (n = 165), had stereoscopic 45 degrees retinal photographs taken of three fields in the right eye after mydriasis. Photographs were graded according to a modified version of the Airlie House criteria. The prevalence of nonproliferative and proliferative retinopathy was: 14.5% and 0.3%, respectively, in newly diagnosed diabetic subjects; 42.0% and 2.3%, respectively, in known diabetic subjects; and 9.1% and 0%, respectively, in persons with impaired glucose tolerance. Muslim Indians had the lowest prevalence of retinopathy (10.8% and 34.0% for new and known diabetes, respectively), but after adjusting for other factors, this was significantly different only to Creoles (18.8% and 53.8%, respectively). Univariate analysis revealed significant differences between diabetic subjects with and without retinopathy in mean age, body mass index, fasting and 2-hour plasma glucose levels, systolic and diastolic blood pressure, fasting triglycerides, serum creatinine, and urinary albumin levels. For known diabetes, mean duration of diabetes and the proportion using insulin were also greater in those with retinopathy. Multivariate analysis using logistic regression confirmed that increasing duration of diabetes, fasting plasma glucose, systolic blood pressure, and urinary albumin concentration, and decreasing body mass index, were independently associated with retinopathy. The high prevalence of diabetic retinopathy observed in all major ethnic groups in Mauritius portends a serious public health problem, given the relative recency of the NIDDM epidemic in that country and the limited resources for laser photocoagulation. Strategies to minimize this problem among those already known to have diabetes should include strict control of plasma glucose and blood pressure.     

Inhibition of membrane lipid peroxidation by a radical scavenging mechanism: a novel function for hydroxyl-containing ionophores

In the present study we show that K+/H+ hydroxyl-containing ionophores lasalocid-A (LAS) and nigericin (NIG) in the nanomolar concentration range, inhibit Fe2+-citrate and 2,2'-azobis(2-amidinopropane) dihydrochloride (ABAP)-induced lipid peroxidation in intact rat liver mitochondria and in egg phosphatidylcholine (PC) liposomes containing negatively charged lipids--dicetyl phosphate (DCP) or cardiolipin (CL)--and KCl as the osmotic support. In addition, monensin (MON), a hydroxyl-containing ionophore with higher affinity for Na+ than for K+, promotes a similar effect when NaCl is the osmotic support. The protective effect of the ionophores is not observed when the osmolyte is sucrose. Lipid peroxidation was evidenced by mitochondrial swelling, antimycin A-insensitive O2 consumption, formation of thiobarbituric acid-reactive substances (TBARS), conjugated dienes, and electron paramagnetic resonance (EPR) spectra of an incorporated lipid spin probe. A time-dependent decay of spin label EPR signal is observed as a consequence of lipid peroxidation induced by both inductor systems in liposomes. Nitroxide destruction is inhibited by butylated hydroxytoluene, a known antioxidant, and by the hydroxyl-containing ionophores. In contrast, valinomycin (VAL), which does not possess alcoholic groups, does not display this protective effect. Effective order parameters (Seff), determined from the spectra of an incorporated spin label are larger in the presence of salt and display a small increase upon addition of the ionophores, as a result of the increase of counter ion concentration at the negatively charged bilayer surface. This condition leads to increased formation of the ion-ionophore complex, the membrane binding (uncharged) species. The membrane-incorporated complex is the active species in the lipid peroxidation inhibiting process. Studies in aqueous solution (in the absence of membranes) showed that NIG and LAS, but not VAL, decrease the Fe2+-citrate-induced production of radicals derived from piperazine-based buffers, demonstrating their property as radical scavengers. Both Fe2+-citrate and ABAP promote a much more pronounced decrease of LAS fluorescence in PC/CL liposomes than in dimyristoyl phosphatidylcholine (DMPC, saturated phospholipid)-DCP liposomes, indicating that the ionophore also scavenges lipid peroxyl radicals. A slow decrease of fluorescence is observed in the latter system, for all lipid compositions in sucrose medium, and in the absence of membranes, indicating that the primary radicals stemming from both inductors also attack the ionophore. Altogether, the data lead to the conclusion that the membrane-incorporated cation complexes of NIG, LAS and MON inhibit lipid peroxidation by blocking initiation and propagation reactions in the lipid phase via a free radical scavenging mechanism, very likely due to the presence of alcoholic hydroxyl groups in all three molecules and to the attack of the aromatic moiety of LAS.