X-Ray Scattering Study of the Smectic−A1Smectic-A_1 to Smectic−A2Smectic-A_2 Transition

X-ray scattering measurements are reported for critical $smectic-A_2$ fluctuations along a line of second-order transitions between the $smectic-A_1$ and $smectic-A_2$ phases in mixtures of hexylphenyl cyanobenzoyloxy benzoate $(DB_6)$ and terephthal-bis-butylaniline (TBBA). The measured exponents $\gamma = 1.46 \pm 0.05$ and $\nu_{\parallel} = \nu_{\perp}= 0.74 \pm 0.03$ are constant along the second-order line and agree with recent heat-capacity measurements and the scaling law, $3\nu + \alpha =2$. They disagree with current theoretical expectations.Engineering and Applied Science

X-Ray Studies of Transitions between Nematic, Smectic−A1,−A2,and−AdSmectic-A_1, -A_2, and -A_d Phases

We report high-resolution x-ray scattering measurements of the critical fluctuations in mixtures of hexylphenyl cyanobenzoyloxy benzoate $(DB_6)$ and terephtal-bis-butylaniline (TBBA). The phase sequence exhibited on cooling pure $DB_6$ (or mixtures with a low concentration of TBBA), is nematic (N) to $smectic-A_d (A_d)$ to $smectic-A_2 (A_2)$. Mixtures with $\gtrsim 12$ molar percent (mol %) of TBBA have a $smectic-A_1 (A_1)$ phase between the nematic and $smectic-A_2$ phases. For each of the second-order transitions the critical-temperature dependence of the susceptibility and correlation lengths are fit to power laws of the form $t^x$ where $t=(T-T_c)/T_c$. For the $N-A_d$ transition in pure $DB_6$ the susceptibility exponent $\beta=1.29 \pm 0.05$ and the parallel and perpendicular correlation-length exponents are $\nu_{\parallel} 0.67 \pm 0.03$ and $\nu_{\perp} =0.52 \pm 0.03$, respectively. Close to the multicritical point (12 mol% TBBA) where the second-order $N-A_1$ line meets the first-order portion of the $A_1-A_2$ line, the $N-A_1$ exponents are $\beta =1.09 \pm 0.05, \mu_{\parallel} 0.57 \pm 0.03, and \nu_{\perp} =0.43 \pm 0.03$. The correlation length anisotropy $(\nu_{\parallel} \neq \nu_{\perp})$ persists along the entire $N-A_1$ line, with the observed exponents decreasing as the concentration approaches the multicritical point. The $A_1-A_2$ line has both first-order and second-order regions. All the measured exponents $(\beta, \nu_{\parallel}, \nu_{\perp})$ were invariant along the second-order portion of the $A_1-A_2$ line and the correlation-length exponents were isotropic $(\nu_{\parallel} = \nu_{\perp})$. The measured exponents were $\beta = 1.46 \pm 0.05$, and $\nu_{\parallel} = \nu_1 = 0.74 \pm 0.03$. These numbers also held close to the tricritical point where the $A_1-A_2$ transition became first order.Engineering and Applied Science

On the Complete Integrability of Nonlinear Dynamical Systems on Discrete Manifolds within the Gradient-Holonomic Approach

A gradient-holonomic approach for the Lax type integrability analysis of differentialdiscrete dynamical systems is devised. The asymptotical solutions to the related Lax equation are studied, the related gradient identity is stated. The integrability of a discrete nonlinear Schredinger type dynamical system is treated in detail.Comment: 20 page

Effects of habitat and livestock on nest productivity of the Asian houbara Chlamydotis macqueenii in Bukhara Province, Uzbekistan

To inform population support measures for the unsustainably hunted Asian houbara Chlamydotis macqueenii (IUCN Vulnerable) we examined potential habitat and land-use effects on nest productivity in the Kyzylkum Desert, Uzbekistan. We monitored 177 nests across different semi-arid shrub assemblages (clay-sand and salinity gradients) and a range of livestock densities (0–80 km-2). Nest success (mean 51.4%, 95% CI 42.4–60.4%) was similar across four years; predation caused 85% of those failures for which the cause was known, and only three nests were trampled by livestock. Nesting begins within a few weeks of arrival when food appears scarce, but later nests were more likely to fail owing to the emergence of a key predator, suggesting foraging conditions on wintering and passage sites may be important for nest productivity. Nest success was similar across three shrub assemblages and was unrelated to landscape rugosity, shrub frequency or livestock density, but was greater with taller mean shrub height (range 13–67 cm) within 50 m. Clutch size (mean = 3.2 eggs) and per-egg hatchability in successful nests (87.5%) did not differ with laying date, shrub assemblage or livestock density. We therefore found no evidence that livestock density reduced nest productivity across the range examined, while differing shrub assemblages appeared to offer similar habitat quality. Asian houbara appear well-adapted to a range of semi-desert habitats and tolerate moderate disturbance by pastoralism. No obvious in situ mitigation measures arise from these findings, leaving regulation and control as the key requirement to render hunting sustainable

Do red deer stags (Cervus elaphus) use roar fundamental frequency (F0) to assess rivals?

It is well established that in humans, male voices are disproportionately lower pitched than female voices, and recent studies suggest that this dimorphism in fundamental frequency (F0) results from both intrasexual (male competition) and intersexual (female mate choice) selection for lower pitched voices in men. However, comparative investigations indicate that sexual dimorphism in F0 is not universal in terrestrial mammals. In the highly polygynous and sexually dimorphic Scottish red deer Cervus elaphus scoticus, more successful males give sexually-selected calls (roars) with higher minimum F0s, suggesting that high, rather than low F0s advertise quality in this subspecies. While playback experiments demonstrated that oestrous females prefer higher pitched roars, the potential role of roar F0 in male competition remains untested. Here we examined the response of rutting red deer stags to playbacks of re-synthesized male roars with different median F0s. Our results show that stags’ responses (latencies and durations of attention, vocal and approach responses) were not affected by the F0 of the roar. This suggests that intrasexual selection is unlikely to strongly influence the evolution of roar F0 in Scottish red deer stags, and illustrates how the F0 of terrestrial mammal vocal sexual signals may be subject to different selection pressures across species. Further investigations on species characterized by different F0 profiles are needed to provide a comparative background for evolutionary interpretations of sex differences in mammalian vocalizations

Exploring the Immunoproteome for Ovarian Cancer Biomarker Discovery

Most scientific efforts towards early detection of ovarian cancer are commonly focused on the discovery of tumour-associated antigens (TAA). Autologous antibodies against TAA, however, may serve as more sensitive diagnostic markers. They circulate in the blood before TAA and are usually more abundant than the TAAs themselves as a result of amplification through the humoral immune response. Accumulating evidence also suggests that a humoral response already exists during malignant transformation when aberrant gene expression is translated into premalignant cellular changes. This article reviews the current knowledge about autoantibodies against TAA in ovarian cancer and presents current immunoproteomic approaches for their detection

Reconciling the biogeography of an invader through recent and historic genetic patterns: the case of topmouth gudgeon Pseudorasbora parva

© 2018 The Author(s) The genetic variability and population structure of introduced species in their native range are potentially important determinants of their invasion success, yet data on native populations are often poorly represented in relevant studies. Consequently, to determine the contribution of genetic structuring in the native range of topmouth gudgeon Pseudorasbora parva to their high invasion success in Europe, we used a dataset comprising of 19 native and 11 non-native populations. A total of 666 samples were analysed at 9 polymorphic microsatellite loci and sequenced for 597 bp of mitochondrial DNA. The analysis revealed three distinct lineages in the native range, of which two haplogroups were prevalent in China (100%), with a general split around the Qinling Mountains. Dating of both haplogroups closely matched past geological events. More recently, its distribution has been influenced by fish movements in aquaculture, resulting in gene flow between previously separated populations in Northern and Southern China. Their phylogeography in Europe indicate as few as two introductions events and two dispersal routes. Microsatellite data revealed native populations had higher genetic diversity than those in the invasive range, a contrast to previous studies on P. parva. This study confirms the importance of extensive sampling in both the native and non-native range of invasive species in evaluating the influence of genetic variability on invasion success

Surfaces modifiées par des monocouches d‟oligothiophènes conjugués pour l‟électronique moléculaire

Date du colloque&nbsp;: 07/2009</p