5,441 research outputs found
Liquid crystal anchoring transitions on aligning substrates processed by plasma beam
We observe a sequence of the anchoring transitions in nematic liquid crystals
(NLC) sandwiched between the hydrophobic polyimide substrates treated with the
plasma beam. There is a pronounced continuous transition from homeotropic to
low tilted (nearly planar) alignment with the easy axis parallel to the
incidence plane of the plasma beam (the zenithal transition) that takes place
as the exposure dose increases. In NLC with positive dielectric anisotropy, a
further increase in the exposure dose results in in-plane reorientation of the
easy axis by 90 degrees (the azimuthal transition). This transition occurs
through the two-fold degenerated alignment characteristic for the second order
anchoring transitions. In contrast to critical behavior of anchoring, the
contact angle of NLC and water on the treated substrates monotonically declines
with the exposure dose. It follows that the surface concentration of
hydrophobic chains decreases continuously. The anchoring transitions under
consideration are qualitatively interpreted by using a simple phenomenological
model of competing easy axes which is studied by analyzing anchoring diagrams
of the generalized polar and non-polar anchoring models.Comment: revtex4, 18 pages, 10 figure
Stability of Quantum Eigenstates and Collapse of Superposition of States in a Fluctuating Vacuum: The Madelung Hydrodynamic Approach
The paper investigates the quantum fluctuating dynamics by using the stochastic generalization of the Madelung quantum-hydrodynamic approach. By using the discrete approach, the path integral solution is derived in order to investigate how the final stationary configuration is obtained from the initial quantum superposition of states. The model shows that the quantum eigenstates remain stationary configurations with a very small perturbation of their mass density distribution and that any eigenstate, contributing to a quantum superposition of states, can be reached in the final stationary configuration. When the non-local quantum potential acquires a finite range of interaction, the work shows that the macroscopic coarse-grained description of the theory can lead to a really classical system. The minimum uncertainty attainable in the stochastic Madelung model is shown to be compatible with maximum speed of transmission of information and interactions. The theory shows that, in the quantum deterministic limit, the uncertainty relations of quantum mechanics are obtained. The connections with the decoherence theory and the Copenhagen interpretation of quantum mechanics are also discussed
Urinary incontinence, work, and intention to leave current job: A cross sectional survey of the Australian nursing and midwifery workforce
© 2017 Wiley Periodicals, Inc. Aims: To determine the prevalence and severity of urinary incontinence (UI) in a group of female nurses and midwives, and to examine the relationship between UI, work and intention to leave current job. Methods: An electronic survey “Fit for the future” was distributed to nurses and midwives in NSW, Australia between May 2014 and February 2015. UI was investigated using the International Consultation on Incontinence UI—Short Form. Examined work characteristics included: work role, location, setting, contract, shift, job satisfaction, and plans to leave current job. Logistic regression modelling was performed to determine whether the severity of UI had an independent effect on intention to leave. Results: Of 5041 survey responses, 68.5% answered the question on urine leakage. Of the included female sample (n = 2,907) the prevalence of UI was 32.0% (95% CI: 30-34%): of these 40.5% experienced moderate and 4.4% “severe or very severe” symptoms. UI was more likely to be reported in nurses or midwives working part-time or days only (not shifts). Those with “severe or very severe UI” were more likely to indicate an intention to leave at 12 months (OR: 2.68; 95% CI: 1.18-6.06) than those with slight or moderate symptoms, after accounting for age, body mass index, parity, pelvic organ prolapse, anxiety, depression, work contract, shift, and job satisfaction. Conclusions: UI is a condition of high prevalence and significant severity in female nurses and midwives. In this workforce, severe UI was associated with intentions related to future employment
Gastaut type-idiopathic childhood occipital epilepsy and childhood absence epilepsy: a clinically significant association?
We report an unusual association between idiopathic occipital epilepsy and childhood absence epilepsy
in 2 pediatric patients. At first clinical and electroencephalographic evaluation, the patients presented
the peculiar signs of idiopathic occipital epilepsy Gastaut type: focal sensory visual seizures, migrainelike
symptoms (only in one patient) and unilateral spike–wave discharges over occipital regions. Both
children were treated with valproic acid and their seizures were rapidly controlled. After a seizure-free
period, the patients presented typical absence with ictal electroencephalographies showing 3 cycles/s
generalized and symmetrical spike–wave complexes. We discuss the possible association between these
two epileptic syndromes and its common pathophysiological mechanisms
Volatile signals during pregnancy: A possible chemical basis for mother-infant recognition
Human pheromones play a role in regulating relationships and apparently influence partner choice and mother–infant recognition. We analyzed the chemical content of volatiles from sweat patch samples from the para-axillary and nipple–areola regions of women during pregnancy and after childbirth. Solid phase microextraction was used to extract the volatile compounds, which were then characterized and quantified by gas chromatography–mass spectrometry. During pregnancy, women developed a distinctive pattern of five volatile compounds common to the para-axillary and nipple–areola regions (1-dodecanol, 1-1′-oxybis octane, isocurcumenol, α-hexyl-cinnamic aldehyde, and isopropyl myristate). These compounds were absent outside pregnancy and had slightly different patterns in samples from the two body areas. Differentiation of the volatile patterns among pregnant women may help newborns to distinguish their own mothers
Cognitive and linguistic abnormalities in benign childhood epilepsy with centrotemporal spikes
Aim: To assess the cognitive function and language ability in children with benign
partial epilepsy with centrotemporal spikes.
Methods: Twenty-five patients with benign partial epilepsy with centrotemporal
spikes were included. They were divided into two subgroups. Group I: 10 patients with rolandic
focus who were not treated. Group II: 15 patients with rolandic focus receiving treatment.
A third Group of 12 healthy subjects have been studied. All children underwent
standardized neuropsychological testing: electroencephalogram recording, Wechsler Intelligence
Scale for Children-revised, Peabody Picture Vocabulary Test-III (PPVT-III) and Boston
Naming Test (BNT), both during active disease (T1) and 2 years after recovery from epilepsy
(T2).
Results: At T1 evaluation, no significant differences in group I and II patients about
general intelligence, when compared with controls, were found. Group I and II patients
were impaired with respect to controls in the receptive and expressive vocabulary evaluated
with PCVT-III and BNT, respectively. At T2 evaluation, group I and II patients showed a normalization
of the language abnormalities.
Conclusion: Deficits of speech-related abilities can be detected in children with this type of epilepsy:
these dysfunctions seem to be independent of the effects of antiepileptic treatment and are
reversible after remission of epilepsy
Fluorescence Probing of Aminofluorene-Induced Conformational Heterogeneity in DNA Duplexes
Fluorescence spectroscopy was used to study carcinogen-induced conformational heterogeneity in DNA duplexes. The fluorophore 2-aminopurine (AP) was incorporated adjacent (5′) to the lesion (G*) in eight different DNA duplexes [d(5′-CTTCTPG*NCCTC-3′):d(5′-GAGGNXTAGAAG-3′), G* = FAF adduct, P = AP, N = G, A, C, T, and X = C, A] modified by FAF [N-(2′-deoxyguanosin-8-yl)-7-fluoro-2-aminofluorene], a fluorine-tagged model DNA adduct derived from the potent carcinogen 2-aminofluorene. Steady-state measurements showed that fluorescence intensity and Stern−Volmer constants (Ksv) derived from acrylamide quenching experiments decreased for all carcinogen-modified duplexes relative to the controls, which suggests greater AP stacking in the duplex upon adduct formation. Conformation-specific stacking of AP with the neighboring adduct was evidenced by a sequence-dependent variation in fluorescence intensity, position of emission maximum, degree of emission quenching by acrylamide, and temperature-dependent spectral changes. The magnitude of stacking was in the order of FAF residue in base-displaced stacked (S) \u3e minor groove wedged (W) \u3e major groove B type (B). This work represents a novel utility of AP in probing adduct-induced conformational heterogeneities in DNA duplexes
Conformational and Thermodynamic Properties Modulate the Nucleotide Excision Repair of 2-Aminofluorene and 2-Acetylaminofluorene dG Adducts in the NarI Sequence
Nucleotide excision repair (NER) is a major repair pathway that recognizes and corrects various lesions in cellular DNA. We hypothesize that damage recognition is an initial step in NER that senses conformational anomalies in the DNA caused by lesions. We prepared three DNA duplexes containing the carcinogen adduct N-(2′-deoxyguanosin-8-yl)-7-fluoro-2-acetylaminofluorene (FAAF) at G1, G2 or G3 of NarI sequence (5′-CCG1G2CG3CC-3′). Our 19F-NMR/ICD results showed that FAAF at G1 and G3 prefer syn S-and W-conformers, whereas anti B-conformer was predominant for G2. We found that the repair of FAAF occurs in a conformation-specific manner, i.e. the highly S/W-conformeric G3 and-G1 duplexes incised more efficiently than the B-type G2 duplex (G3∼G1\u3eG2). The melting and thermodynamic data indicate that the S-and W-conformers produce greater DNA distortion and thermodynamic destabilization. The N-deacetylated N-(2′-deoxyguanosin-8-yl)-7-fluoro-2-aminofluorene (FAF) adducts in the same NarI sequence are repaired 2-to 3-fold less than FAAF: however, the incision efficiency was in order of G2∼G1\u3eG 3, a reverse trend of the FAAF case. We have envisioned the so-called N-acetyl factor as it could raise conformational barriers of FAAF versus FAF. The present results provide valuable conformational insight into the sequence-dependent UvrABC incisions of the bulky aminofluorene DNA adducts
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