37 research outputs found
Nematic-isotropic phase transition in diblock fused-sphere chain fluids
No full textA density-functional theory for the isotropic-nematic phase transition in fluids of rigid or semiflexible fused hard-sphere chains, developed previously by the authors, is extended to diblock chains each consisting of both a rigid and a flexible part. The theory is compared with recent Monte Carlo simulation results of McBride The theoretical results for the variation of pressure and nematic order parameter with density agree well with the simulation data over density ranges where the simulations find isotropic and nematic phases.PT: J; CR: BOUBLIK T, 1974, MOL PHYS, V27, P1415 BOUBLIK T, 1975, J CHEM PHYS, V63, P4084 BOUBLIK T, 1981, MOL PHYS, V44, P1369 BOUBLIK T, 1989, MOL PHYS, V68, P191 COTTER MA, 1977, J CHEM PHYS, V66, P1098 COTTER MA, 1978, PHYS REV A, V18, P2669 FORSMAN J, 2003, J CHEM PHYS, V119, P1889 FYNEWEVER H, 1998, J CHEM PHYS, V108, P1636 HONNELL KG, 1989, J CHEM PHYS, V90, P1841 JAFFER KM, 1999, J CHEM PHYS, V110, P11630 JAFFER KM, 2001, J CHEM PHYS, V114, P3314 KHOKHLOV AR, 1981, PHYSICA A, V108, P546 KHOKHLOV AR, 1982, PHYSICA A, V112, P605 MCBRIDE C, 2001, PHYS REV E 1, V64 MCBRIDE C, 2002, J CHEM PHYS, V117, P10370 MEHTA SD, 1996, J PHYS CHEM-US, V100, P10408 MULLER M, 2003, J CHEM PHYS, V118, P2929 SATO T, 1996, ADV POLYM SCI, V126, P85 TIAN P, 2001, J CHEM PHYS, V115, P9055 VARGA S, 2000, MOL PHYS, V98, P693 VEGA C, 1994, J CHEM PHYS, V100, P6727 WERTHEIM MS, 1987, J CHEM PHYS, V87, P7323 WHITTLE M, 1991, MOL PHYS, V72, P247 WILLIAMSON DC, 1995, MOL PHYS, V86, P819 WILLIAMSON DC, 1998, J CHEM PHYS, V108, P10294 YETHIRAJ A, 1998, MOL PHYS, V93, P693 ZHOU YQ, 1995, J CHEM PHYS, V103, P2688; NR: 27; TC: 3; J9: PHYS REV E; PN: Part 1; PG: 4; GA: 835RHSource type: Electronic(1
The nematic-isotropic phase transition in semiflexible fused hard-sphere chain fluids
No full textA density-functional theory of the isotropic-nematic phase transition in both rigid and semiflexible hard-sphere chain fluids is described. The theory is based on an exact analytical evaluation of the excluded volume and second virial coefficient B-2 for rigid chain molecules, which demonstrates that B-2 in these cases is equivalent to that of a binary mixture of hard spheres and hard diatomic molecules. It is assumed that the same binary-mixture representation applies to semiflexible chains, while scaled particle theory is used to obtain the properties of the fluid at arbitrary densities. The results of the theory are in very good agreement with Monte Carlo (MC) simulation data for rigid tangent hard-sphere chains, but in lesser agreement with available MC studies of rigid fused hard-sphere chains. We find that there is reasonable agreement between the theory and MC data for semiflexible tangent chains, which improves with increasing chain length. The behavior predicted by the theory for semiflexible chains is contrasted with that given by the Khokhlov and Semenov theory of nematic ordering of wormlike polymer chains. (C) 2001 American Institute of Physics.PT: J; CR: BOUBLIK T, 1974, MOL PHYS, V27, P1415 BOUBLIK T, 1975, J CHEM PHYS, V63, P4084 BOUBLIK T, 1977, CHEM PHYS LETT, V46, P315 BOUBLIK T, 1981, MOL PHYS, V44, P1369 BOUBLIK T, 1989, MOL PHYS, V68, P191 BOUBLIK T, 1990, J CHEM PHYS, V93, P730 CARNAHAN NF, 1969, J CHEM PHYS, V51, P635 CHAPMAN WG, 1988, MOL PHYS, V65, P1057 CHEN ZY, 1993, MACROMOLECULES, V26, P3419 COSTA LA, 1995, J CHEM PHYS, V102, P6212 COTTER MA, 1977, J CHEM PHYS, V66, P1098 COTTER MA, 1978, PHYS REV A, V18, P2669 DIJKSTRA M, 1995, PHYS REV E A, V51, P5891 ESCOBEDO FA, 1997, J CHEM PHYS, V106, P9858 FYNEWEVER H, 1998, J CHEM PHYS, V108, P1636 GAO J, 1989, J CHEM PHYS, V91, P3168 HONNELL KG, 1989, J CHEM PHYS, V90, P1841 JAFFER KM, 1999, J CHEM PHYS, V110, P11630 KHOKHLOV AR, 1981, PHYSICA A, V108, P546 KHOKHLOV AR, 1982, PHYSICA A, V112, P605 LEE SD, 1987, J CHEM PHYS, V87, P4972 MEHTA SD, 1996, J PHYS CHEM-US, V100, P10408 MULLER M, 1998, PHYS REV E, V57, P6973 ONSAGER L, 1949, ANN NY ACAD SCI, V51, P627 PARSONS JD, 1979, PHYS REV A, V19, P1225 PATRA CN, 2000, J CHEM PHYS, V112, P1579 SEN S, 1994, J CHEM PHYS, V101, P9010 VARGA S, 2000, MOL PHYS, V98, P693 VEGA C, 1994, J CHEM PHYS, V100, P6727 WALSH JM, 1990, J PHYS CHEM-US, V94, P5115 WERTHEIM MS, 1987, J CHEM PHYS, V87, P7323 WHITTLE M, 1991, MOL PHYS, V72, P247 WILLIAMSON DC, 1995, MOL PHYS, V86, P819 WILLIAMSON DC, 1998, J CHEM PHYS, V108, P10294 YETHIRAJ A, 1992, MACROMOLECULES, V25, P3979 YETHIRAJ A, 1995, J CHEM PHYS, V102, P5499 YETHIRAJ A, 1995, J CHEM PHYS, V102, P6874 YETHIRAJ A, 1998, MOL PHYS, V93, P693 ZHOU YQ, 1995, J CHEM PHYS, V103, P2688; NR: 39; TC: 8; J9: J CHEM PHYS; PG: 11; GA: 397THSource type: Electronic(1
The nematic-isotropic phase transition in linear fused hard-sphere chain fluids
No full textWe present a modification of the generalized Flory dimer theory to investigate the nematic (N) to isotropic (I) phase transition in chain fluids. We focus on rigid linear fused hard-sphere (LFHS) chain molecules in this study. A generalized density functional theory is developed, which involves an angular weighting of the dimer reference fluid as suggested by decoupling theory, to accommodate nematic ordering in the system. A key ingredient of this theory is the calculation of the exact excluded volume for a pair of molecules in an arbitrary relative orientation, which extends the recent work by Williamson and Jackson for linear tangent hard-sphere chain molecules to the case of linear fused hard-sphere chains with arbitrary intramolecular bondlength. The present results for the N-I transition are compared with previous theories and with computer simulations. In comparison with previous studies, the results show much better agreement with simulations for both the coexistence densities and the nematic order parameter at the transition. (C) 1999 American Institute of Physics. [S0021-9606(99)51023-4].PT: J; CR: BOLHUIS P, 1997, J CHEM PHYS, V106, P666 BOUBLIK T, 1977, CHEM PHYS LETT, V46, P315 BOUBLIK T, 1989, MOL PHYS, V68, P191 CARNAHAN NF, 1969, J CHEM PHYS, V51, P635 CHAMOUX A, 1998, MOL PHYS, V93, P649 CHANDLER D, 1976, J CHEM PHYS, V65, P2925 CHANG J, 1994, CHEM ENG SCI, V49, P2777 CHAPMAN WG, 1988, MOL PHYS, V65, P1057 CHIEW YC, 1990, MOL PHYS, V70, P129 COSTA LA, 1995, J CHEM PHYS, V102, P6212 CURRO JG, 1987, MACROMOLECULES, V20, P1928 FYNEWEVER H, 1998, J CHEM PHYS, V108, P1636 HONNELL KG, 1989, J CHEM PHYS, V90, P1841 JAFFER KM, 1999, THESIS U GUELPH KIERLIK E, 1992, J CHEM PHYS, V97, P9222 KIERLIK E, 1993, J CHEM PHYS, V99, P3950 LEE SD, 1987, J CHEM PHYS, V87, P4972 MEHTA SD, 1996, J PHYS CHEM-US, V100, P10408 ONSAGER L, 1949, ANN NY ACAD SCI, V51, P627 PADILLA P, 1997, J CHEM PHYS, V106, P10299 PARSONS JD, 1979, PHYS REV A, V19, P1225 PRATT LR, 1977, J CHEM PHYS, V66, P147 SCHWEIZER KS, 1988, MACROMOLECULES, V21, P3070 SEN S, 1994, J CHEM PHYS, V101, P9010 SOMOZA AM, 1989, J CHEM PHYS, V91, P517 STELL G, 1964, EQUILIBRIUM THEORY C TILDESLEY DJ, 1980, MOL PHYS, V41, P85 VEGA C, 1994, J CHEM PHYS, V100, P6727 WERTHEIM MS, 1987, J CHEM PHYS, V87, P7323 WHITTLE M, 1991, MOL PHYS, V72, P247 WILLIAMSON DC, 1995, MOL PHYS, V86, P819 WILLIAMSON DC, 1998, J CHEM PHYS, V108, P10294 WOODWARD CE, 1994, J CHEM PHYS, V100, P3181 YETHIRAJ A, 1993, J CHEM PHYS, V98, P1635 YETHIRAJ A, 1995, J CHEM PHYS, V102, P5499 YETHIRAJ A, 1998, MOL PHYS, V93, P693 ZHOU YQ, 1995, J CHEM PHYS, V103, P2688; NR: 37; TC: 15; J9: J CHEM PHYS; PG: 13; GA: 200CHSource type: Electronic(1
Effect of Some Disinfectant Solutions on the Adherence of Candida albicans to Three Types of Acrylic Resin Denture Base Materials
No full textObjective: Microbial adhesion to denture surface is problematic for denture wearers, especially those with impaired dexterities. This study aimed to evaluate the effectiveness of two plant extracts (clove and Basil) in addition to Chlorhexidine on candida Albicans adherence to (heat, cold, light) activated acrylic denture base materials. Methods: Two herbal extracted clove (Eugenia caryohyllata) and Basil (Ocimum basilicum) were prepared by drying, ground to powder, and extracted with ethanol chlorhexidine gluconate of 0.12% were used as three disinfectant solutions. One hundred and five square acrylic samples were prepared from (heat, cold, and light) activated acrylic resin denture base materials in dimensions of 10×10×2 mm for the study. The disk diffusion test was used to determine the susceptibility of C. Albicans to disinfectant solutions. The adhesion of yeast to the acrylic resin samples was measured with a light microscope by measuring the number of fungal cells in the corners of the square and expressed as no. of cells/mm2. Statistical analysis was done by ANOVA to compare the mean of readings between disinfectant solutions and post-hoc t-test in which the p-value is less than 0.05. Results: Statistically significant differences (p 0.05) of adhesion of C.albicans were found on the surfaces of three types of activated acrylic resin materials with means of 19.18, 46.25, and 26.50 cell/mm2on heat, light, and cold cure respectively and after immersing the specimens on the disinfectant solutions regarding the highest effect of the disinfectant solutions was seen in chlorhexidine gluconate of 0.12% which demonstrate 3.11, 5.89 and 5.43 cell/mm2 followed by Basil with means of 6.75, 13.57 and 10.11 cell/mm2 on heat, light and cold cure acrylic resin specimens correspondingly, then the clove and finally distilled water. Conclusions: Both clove buds and basil leaves extracted solutions exhibited high antifungal activity besides Chlorhexidine on the surface of denture base materials. The highest inhibition zone was seen in Chlorhexidine, followed by Basil, clove, and distilled water, respectively. The number of fungal cell adhesion to the three types of denture base was decreased in the three disinfectant solutions when compared to distilled water (control group)
Magnetic activity and hot Jupiters of young Suns : the weak-line T Tauri stars V819 Tau and V830 Tau
No full textSGG acknowledges support from the Science & Technology Facilities Council (STFC) via an Ernest Rutherford Fellowship [ST/J003255/1]. SHPA acknowledges financial support from CNPq, CAPES and Fapemig. AAV acknowledges support from the Swiss National Science Foundation (SNSF) via the allocation of an Ambizione Followship. Date of Acceptance: 06/08/2015We report results of a spectropolarimetric and photometric monitoring of the weak-line T Tauri stars (wTTSs) V819 Tau and V830 Tau within the MaTYSSE (Magnetic Topologies of Young Stars and the Survival of close-ingiant Exoplanets) programme, involving the ESPaDOnS spectropolarimeter at the Canada-France-Hawaii Telescope. At ≃3 Myr, both stars dissipated their discs recently and are interesting objects for probing star and planet formation. Profile distortions and Zeeman signatures are detected in the unpolarized and circularly polarized lines, whose rotational modulation we modelled using tomographic imaging, yielding brightness and magnetic maps for both stars. We find that the large-scale magnetic fields of V819 Tau and V830 Tau are mostly poloidal and can be approximated at large radii by 350-400 G dipoles tilted at≃30° to the rotation axis. They are significantly weaker than the field of GQ Lup, an accreting classical T Tauri star (cTTS) with similar mass and age which can be used to compare the magnetic properties of wTTSs and cTTSs. The reconstructed brightness maps of both stars include cool spots and warm plages. Surface differential rotation is small, typically ≃4.4 times smaller than on the Sun, in agreement with previous results on wTTSs. Using our Doppler images to model the activity jitter and filter it out from the radial velocity(RV) curves, we obtain RV residuals with dispersions of 0.033 and 0.104km s-1 for V819 Tau and V830 Tau, respectively. RV residuals suggest that a hot Jupiter may be orbiting V830 Tau, though additional data are needed to confirm this preliminary result. We find no evidence for close-in giant planet around V819 Tau.Peer reviewe
COVID-19 Pandemic–Related Prenatal Distress and Infant Functional Brain Development
No full textObjective: Psychological distress (eg, anxiety and depression) during pregnancy can disrupt fetal brain development and negatively affect infant behavior. Prenatal distress rose substantially during the COVID-19 pandemic according to most, but not all, studies, raising concerns about its potential effects on brain connectivity and behavior in infants. Method: We investigated 63 mother–infant pairs as part of the Pregnancy during the COVID-19 Pandemic study. Mothers reported depression and anxiety symptoms prospectively during pregnancy; these were combined into one measure of prenatal maternal distress. Infant brain resting state functional magnetic resonance imaging (rs-fMRI) scans were obtained at 3 months of age, and mothers assessed infant behavior at 6 and 12 months using the Infant Behavior Questionnaire—Revised (IBQ-R) and the Ages and Stages Questionnaire (ASQ-3), respectively. The rs-fMRI was processed to measure functional connectivity within auditory, left frontoparietal, and default mode networks, and connectivity was tested for relationships to prenatal maternal distress. Prenatal distress and brain connectivity were also tested for relationships with infant behavior. Results: Higher prenatal maternal distress was related to stronger functional connectivity in the infant auditory network (T = 2.5, p = 0.01, q = 0.04, df = 59) and higher infant ASQ-3 personal–social scores (T = 2.9, p = 0.006, q = 0.03, df = 48). No significant associations were found between brain connectivity and infant behavior. Conclusion: The impact of exposure to maternal prenatal distress on infant brain networks may be more apparent in networks that develop early, such as the auditory network, compared to later-developing networks, the effects of which may emerge later in childhood. The link between prenatal maternal distress and higher infant behavior scores may suggest compensatory changes, although further study is needed to determine how behavior manifests in the longer term. Plain language summary: During the COVID-19 pandemic, pregnant individuals were especially stressed, but the impacts on infant brain development are still unclear. This study measured anxiety and depression symptoms in 63 mothers during pregnancy and performed resting-state functional brain magnetic resonance imaging scans in their infants at 3 months of age at the Alberta Children’s Hospital. Mothers who experienced higher distress during pregnancy had infants with stronger functional communication within the auditory brain network and more advanced social behaviors. Our findings show the importance of studying a range of brain regions beyond those involved in emotion and suggest the need for continued monitoring of this infant cohort through early childhood. Diversity & Inclusion Statement: We worked to ensure sex and gender balance in the recruitment of human participants. We worked to ensure race, ethnic, and/or other types of diversity in the recruitment of human participants. We worked to ensure that the study questionnaires were prepared in an inclusive way. One or more of the authors of this paper self-identifies as a member of one or more historically underrepresented racial and/or ethnic groups in science. One or more of the authors of this paper self-identifies as a member of one or more historically underrepresented sexual and/or gender groups in science. The author list of this paper includes contributors from the location and/or community where the research was conducted who participated in the data collection, design, analysis, and/or interpretation of the work. We actively worked to promote inclusion of historically underrepresented racial and/or ethnic groups in science in our author group. We actively worked to promote sex and gender balance in our author group
International standards for early fetal size and pregnancy dating based on ultrasound measurement of crown-rump length in the first trimester of pregnancy.
No full textOBJECTIVES: There are no international standards for relating fetal crown-rump length (CRL) to gestational age (GA), and most existing charts have considerable methodological limitations. The INTERGROWTH-21(st) Project aimed to produce the first international standards for early fetal size and ultrasound dating of pregnancy based on CRL measurement.
METHODS: Urban areas in eight geographically diverse countries that met strict eligibility criteria were selected for the prospective, population-based recruitment, between 9 + 0 and 13 + 6 weeks' gestation, of healthy well-nourished women with singleton pregnancies at low risk of fetal growth impairment. GA was calculated on the basis of a certain last menstrual period, regular menstrual cycle and lack of hormonal medication or breastfeeding in the preceding 2 months. CRL was measured using strict protocols and quality-control measures. All women were followed up throughout pregnancy until delivery and hospital discharge. Cases of neonatal and fetal death, severe pregnancy complications and congenital abnormalities were excluded from the study.
RESULTS: A total of 4607 women were enrolled in the Fetal Growth Longitudinal Study, one of the three main components of the INTERGROWTH-21(st) Project, of whom 4321 had a live singleton birth in the absence of severe maternal conditions or congenital abnormalities detected by ultrasound or at birth. The CRL was measured in 56 women at < 9 + 0 weeks' gestation; these were excluded, resulting in 4265 women who contributed data to the final analysis. The mean CRL and SD increased with GA almost linearly, and their relationship to GA is given by the following two equations (in which GA is in days and CRL in mm): mean CRL = -50.6562 + (0.815118 × GA) + (0.00535302 × GA(2) ); and SD of CRL = -2.21626 + (0.0984894 × GA).
GA estimation is carried out according to the two equations: GA = 40.9041 + (3.21585 × CRL(0.5) ) + (0.348956 × CRL); and SD of GA = 2.39102 + (0.0193474 × CRL).
CONCLUSIONS: We have produced international prescriptive standards for early fetal linear size and ultrasound dating of pregnancy in the first trimester that can be used throughout the world
Erratum: The Cancer Genome Atlas Comprehensive Molecular Characterization of Renal Cell Carcinoma (Cell Reports (2018) 23(1) (313–326.e5) (S2211124718304364) (10.1016/j.celrep.2018.03.075))
No full text(Cell Reports 23, 313–326; April 3, 2018) In the originally published version of this article, the author list contained two errors. Specifically, David J. Kwiatkowski was misspelled as David J. Kwaitkowski, and William Y. Kim was inadvertently written as William T. Kim. Both names have been corrected online. The authors regret this error
HOT GAS LINES IN T TAURI STARS
No full textFor Classical T Tauri Stars (CTTSs), the resonance doublets of NV, Si IV, and C IV, as well as the He II 1640 angstrom line, trace hot gas flows and act as diagnostics of the accretion process. In this paper we assemble a large high-resolution, high-sensitivity data set of these lines in CTTSs and Weak T Tauri Stars (WTTSs). The sample comprises 35 stars: 1 Herbig Ae star, 28 CTTSs, and 6 WTTSs. We find that the C IV, Si IV, and N V lines in CTTSs all have similar shapes. We decompose the C IV and He II lines into broad and narrow Gaussian components (BC and NC). The most common (50%) C IV line morphology in CTTSs is that of a low-velocity NC together with a redshifted BC. For CTTSs, a strong BC is the result of the accretion process. The contribution fraction of the NC to the C IV line flux in CTTSs increases with accretion rate, from similar to 20% to up to similar to 80%. The velocity centroids of the BCs and NCs are such that V-BC greater than or similar to 4 V-NC, consistent with the predictions of the accretion shock model, in at most 12 out of 22 CTTSs. We do not find evidence of the post-shock becoming buried in the stellar photosphere due to the pressure of the accretion flow. The He II CTTSs lines are generally symmetric and narrow, with FWHM and redshifts comparable to those of WTTSs. They are less redshifted than the CTTSs C IV lines, by similar to 10 km s(-1). The amount of flux in the BC of the He II line is small compared to that of the C IV line, and we show that this is consistent with models of the pre-shock column emission. Overall, the observations are consistent with the presence of multiple accretion columns with different densities or with accretion models that predict a slow-moving, low-density region in the periphery of the accretion column. For HN Tau A and RW Aur A, most of the C IV line is blueshifted suggesting that the C IV emission is produced by shocks within outflow jets. In our sample, the Herbig Ae star DX Cha is the only object for which we find a P-Cygni profile in the C IV line, which argues for the presence of a hot (105 K) wind. For the overall sample, the Si IV and N V line luminosities are correlated with the C IV line luminosities, although the relationship between Si IV and C IV shows large scatter about a linear relationship and suggests that TW Hya, V4046 Sgr, AA Tau, DF Tau, GM Aur, and V1190 Sco are silicon-poor, while CV Cha, DX Cha, RU Lup, and RW Aur may be silicon-rich.http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000322631500001&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701Astronomy & AstrophysicsSCI(E)22ARTICLE1null20
Systematic review and economic modelling of the relative clinical benefit and cost-effectiveness of laparoscopic surgery and robotic surgery for removal of the prostate in men with localised prostate cancer
No full textPMID: 23127367 [PubMed - indexed for MEDLINE] Free full text Funding for this study was provided by the Health Technology Assessment programme of the National Institute for Health Research.Peer reviewe
