Annual variation in predation risk is related to the direction of selection for brain size in the wild

The direction of predator-mediated selection on brain size is debated. However, the speed and the accuracy of performing a task cannot be simultaneously maximized. Large-brained individuals may be predisposed to accurate but slow decision-making, beneficial under high predation risk, but costly under low risk. This creates the possibility of temporally fluctuating selection on brain size depending on overall predation risk. We test this idea in nesting wild eider females (Somateria mollissima), in which head volume is tightly linked to brain mass (r(2) = 0.73). We determined how female relative head volume relates to survival, and characterized the seasonal timing of predation. Previous work suggests that relatively large-brained and small-brained females make slow versus fast nest-site decisions, respectively, and that predation events occur seasonally earlier when predation is severe. Large-brained, late-breeding females may therefore have higher survival during high-predation years, but lower survival during safe years, assuming that predation disproportionately affects late breeders in such years. Relatively large-headed females outsurvived smaller-headed females during dangerous years, whereas the opposite was true in safer years. Predation events occurred relatively later during safe years. Fluctuations in the direction of survival selection on relative brain size may therefore arise due to brain-size dependent breeding phenology.Peer reviewe

On kappa-deformation and triangular quasibialgebra structure

We show that, up to terms of order 1/kappa^5, the kappa-deformed Poincare algebra can be endowed with a triangular quasibialgebra structure. The universal R matrix and coassociator are given explicitly to the first few orders. In the context of kappa-deformed quantum field theory, we argue that this structure, assuming it exists to all orders, ensures that states of any number of identical particles, in any representation, can be defined in a kappa-covariant fashion.Comment: 17 pages, Latex, typos corrected, references added, misleading comments on twisting remove

Bipolar resistive switching characteristics of poly(3,4-ethylene-dioxythiophene): poly(styrenesulfonate) thin film

We investigated the reversible resistive switching of poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS) thin films sandwiched between Al electrodes. The J-V sweep curve showed a hysteretic behavior which depends on the polarity of the applied voltage bias. From the analysis of I-V curves, it was revealed that the charge transport through the junction was governed by the bulk space-charge-limited conduction (SCLC) model. Using transmission electron microscopy (TEM) analysis, it was confirmed that the initial high resistance state of PEDOT:PSS films is related with the segregation of PSS- chains induced by redox reaction between a Al metal electrode and PEDOT:PSS film. Positive space charges present on the top region of PEDOT:PSS films can be proposed as a possible trap centers of electron trapping and detrapping process.Comment: 10 pages, 4 figure

Sex Differences in a Cross Sectional Study of Age-related Hearing Loss in Korean

ObjectivesThe purpose of this study was to obtain sex- and age-specific reference level for hearing threshold of normal aging in Korean and to determine if the rate of change in pure-tone hearing thresholds differed by sex.MethodsSubjects were clients who visited the Health Promotion Center, Daegu Fatima Hospital, Daegu, Korea, from January 2004 to September 2005. Pure-tone audiometric measures were obtained from 3,470 subjects who also completed a hearing questionnaire. The slope of a linear regression was used to estimate the rate of change in pure-tone thresholds at 0.25 to 8 kHz for each ear in 214 men and 902 women without past history of otorrhea, usage of ototoxic drugs, head injury, job in noisy environment, and military service.ResultsHearing thresholds were elevated with age in all test frequencies. Significant sex differences were found in pure-tone thresholds at 4 and 8 kHz after adjusting for age using analysis of covariance. In those high frequencies, hearing was worse in men than in women. The average rate of change in threshold was 0.28 and 0.24 dB per year at 0.25 kHz, increasing gradually to 1.27 and 1.05 dB per year at 8 kHz for men and women, respectively. Men had significantly faster rates of threshold increase at 4 and 8 kHz than women.ConclusionThese cross-sectional measures of hearing levels and rate of threshold increases at 4 and 8 kHz showed significant sex differences in Korean men and women with little evidence of noise-induced hearing loss

Incidental Diagnosis of the Unicuspid Aortic Valve with Ascending Aortic Aneurysm in an Asymptomatic Adult

The unicuspid aortic valve is an extremely rare congenital anomaly. It usually presents with aortic stenosis and/or aortic regurgitation. Other cardiovascular complications, such as aortic dilatation and left ventricular hypertrophy can accompany it. Herein, we present a case report of a 50-year-old asymptomatic male patient with unicuspid aortic valve, complicated by ascending aortic aneurysm

A Case of Crystalline Keratopathy in Monoclonal Gammopathy of Undetermined Significance (MGUS)

A 62-year-old female visited our clinic with progressively decreased vision in both eyes beginning 12 years prior. Idiopathic corneal opacity in all layers of the cornea was found in both eyes. One year later, we performed penetrating keratoplasty on the undiagnosed right eye. During post-surgical follow-up, corneal edema and stromal opacity recurred, and penetrating keratoplasty was performed two more times. The patient's total serum protein level, which had previously been normal, was elevated prior to the final surgery. She was diagnosed with monoclonal gammopathy of undetermined significance. We made a final diagnosis of monoclonal gammopathy-associated crystalline keratopathy after corneal biopsy. Monoclonal gammopathy-associated crystalline keratopathy is difficult to diagnose and may lead to severe visual loss. A systemic work-up, including serologic tests like serum protein or cholesterol levels, is needed in patients with unexplainable corneal opacity

Covariant particle statistics and intertwiners of the kappa-deformed Poincare algebra

To speak about identical particles - bosons or fermions - in quantum field theories with kappa-deformed Poincare symmetry, one must have a kappa-covariant notion of particle exchange. This means constructing intertwiners of the relevant representations of kappa-Poincare. We show, in the simple case of spinless particles, that intertwiners exist, and, supported by a perturbative calculation to third order in 1/kappa, make a conjecture about the existence and uniqueness of a certain preferred intertwiner defining particle exchange in kappa-deformed theories.Comment: 16 pages, latex; v2, references adde

Comparison of 1.5T and 3T 1H MR Spectroscopy for Human Brain Tumors

OBJECTIVE: We wanted to estimate the practical improvements of 3T proton MR spectroscopy ((1)H MRS) as compared with 1.5T (1)H MRS for the evaluation of human brain tumors. MATERIALS AND METHODS: Single voxel (1)H MRS was performed at both 1.5T and 3T in 13 patients suffering with brain tumors. Using the same data acquisition parameters at both field strengths, the (1)H MRS spectra were obtained with a short echo time (TE) (35 msec) and an intermediate TE (144 msec) with the voxel size ranging from 2.0 cm(3) to 8.7 cm(3). The signal to noise ratios (SNRs) of the metabolites (myoinositol [MI], choline compounds [Cho], creatine /phosphocreatine [Cr], N-acetyl-aspartate [NAA], lipid and lactate [LL]) and the metabolite ratios of MI/Cr, Cho/Cr, Cho/NAA and LL/Cr were compared at both TEs between the two field strengths in each brain tumor. The degrees of spectral resolution between the Cho and Cr peaks were qualitatively compared between the two field strengths in each brain tumor. RESULTS: The SNRs of the metabolites at 3T demonstrated 49-73% increase at a short TE (p 0.05) compared with those of 1.5T. The SNR of inverted lactate at an intermediate TE decreased down to 49% with poorer inversion at 3T (p < 0.05). There was no significant difference in the metabolite ratios between the two field strengths. The degrees of the spectral resolution at 3T were slightly superior to those of 1.5T at a short TE. CONCLUSION: As compared with 1.5T, 3T 1H MRS demonstrated 49-73% SNR increase in the cerebral metabolites and slightly superior spectral resolution only at a short TE, but little at an intermediate TE, in the brain tumors. There was no significant difference in the metabolite ratios between the two field strengths