Bending Analysis of Nonlocal Functionally Graded Beams

In this paper, we study the nonlocal linear bending behavior of functionally graded beams subjected to distributed loads. A finite element formulation for an improved first-order shear deformation theory for beams with five independent variables is proposed. The formulation takes into consideration 3D constitutive equations. Eringen's nonlocal differential model is used to rewrite the nonlocal stress resultants in terms of displacements. The finite element formulation is derived by means of the principle of virtual work. High-order nodal-spectral interpolation functions were utilized to approximate the field variables, which minimizes the locking problem. Numerical results and comparisons of the present formulation with those found in the literature for typical benchmark problems involving nonlocal beams are found to be satisfactory and show the validity of the developed finite element model

Geometric inflation

We argue that the presence of an inflationary epoch is a natural, almost unavoidable, consequence of the existence of a sensible action involving an infinite tower of higher-curvature corrections to the Einstein-Hilbert action. No additional fields besides the metric are required. We show that a family of such corrections giving rise to a well-posed cosmological evolution exists and automatically replaces the radiation-dominated early-universe Big Bang by a period of exponential growth of the scale factor, which is gracefully connected with standard late-time ΛCDM cosmology. The class of higher-curvature theories giving rise to sensible cosmological evolution share additional remarkable properties such as the existence of Schwarzschild-like non-hairy black holes, or the fact that, just like for Einstein gravity, the only degrees of freedom propagated on the vacuum are those of the standard graviton.GA acknowledges the support of the CONACYT postdoctoral fellowship. The work of PB was supported by the Simons Foundation through the It From Qubit Simons collaboration. The work of PAC is funded by Fundación Caixa through a “la Caixa - Severo Ochoa” International pre-doctoral grant and partially by the MINECO/FEDER, UE grant FPA2015-66793-P, and the “Centro de Excelencia Severo Ochoa” Program grant SEV-2016-0597. The work of JDE is supported by MINECO FPA2014-52218 and FPA2017-84436-P, Xunta de Galicia ED431C 2017/07, FEDER, and the María de Maeztu Unit of Excellence MDM-2016-0692. The work of RAH is supported by the Natural Sciences and Engineering Research Council of Canada through the Banting Postdoctoral Fellowship programmeS

Proline dehydrogenase from Thermus thermophilus does not discriminate between FAD and FMN as cofactor

Flavoenzymes are versatile biocatalysts containing either FAD or FMN as cofactor. FAD often binds to a Rossmann fold, while FMN prefers a TIM-barrel or flavodoxin-like fold. Proline dehydrogenase is denoted as an exception: it possesses a TIM barrel-like fold while binding FAD. Using a riboflavin auxotrophic Escherichia coli strain and maltose-binding protein as solubility tag, we produced the apoprotein of Thermus thermophilus ProDH (MBP-TtProDH). Remarkably, reconstitution with FAD or FMN revealed that MBP-TtProDH has no preference for either of the two prosthetic groups. Kinetic parameters of both holo forms are similar, as are the dissociation constants for FAD and FMN release. Furthermore, we show that the holo form of MBP-TtProDH, as produced in E. coli TOP10 cells, contains about three times more FMN than FAD. In line with this flavin content, the crystal structure of TtProDH variant ¿ABC, which lacks helices aA, aB and aC, shows no electron density for an AMP moiety of the cofactor. To the best of our knowledge, this is the first example of a flavoenzyme that does not discriminate between FAD and FMN as cofactor. Therefore, classification of TtProDH as an FAD-binding enzyme should be reconsidered

Evaluation and Quantitation of Intact Wax Esters of Human Meibum by Gas-Liquid Chromatography-Ion Trap Mass Spectrometry

PURPOSE. Wax esters (WE) of human meibum are one of the largest group of meibomian lipids. Their complete characterization on the level of individual intact lipid species has not been completed yet. We obtained detailed structural information on previously uncharacterized meibomian WE. METHODS. Intact WE were separated and analyzed by means of high-temperature capillary gas-liquid chromatography (GLC) in combination with low voltage (30 eV) electron ionization ion trap mass spectrometry (ITMS). 3D (mass-to-charge ratio [m/z] versus lipid sample weight versus signal intensity) calibration plots were used for quantitation of WE. RESULTS. We demonstrated that GLC-ITMS was suitable for analyzing unpooled/underivatized WE collected from 14 individual donors. More than 100 of saturated and unsaturated WE (SWE and UWE, respectively) were detected. On average, UWE represented about 82% of the total WE pool. About 90% of UWE were based on oleic acid, while less than 10% were based on palmitoleic acid. The amounts of poly-UWE were <3% of their mono-UWA counterparts. SWE were based primarily on C 16 -C 18 fatty acids (FA) in overall molar ratios of 22:65:13. A pool of C 16:0 -FA was comprised of a 20:80 (mol/ mol) mixture of straight chain and iso-branched isomers, while the corresponding ratio for C 18:0 -FA was 43:57. Interestingly, C 17:0 -FA was almost exclusively branched, with anteiso-and isoisomers found in a ratio of 93:7. CONCLUSIONS. GLC-ITMS can be used successfully to analyze more than 100 individual species of meibomian WE, which were shown to comprise 41 6 8% (wt/wt) of meibum, which made them the largest group of lipids in meibum. (Invest Ophthalmol Vis Sci. 2012;53:3766-3781 1 This secretion has a critical role in protecting the surface of the human eye from desiccation by mixing with aqueous tears (produced by lacrimal glands) and forming the outermost part of the tear film layer, the tear film lipid layer. This lipid-rich layer ''seals'' the underlaying aqueous layer of the tear film, keeping the ocular surface moist, which is critical for its health and good vision. 2,3 Over a period of more than four decades, meibomian WE have been evaluated in a number of studies of animals and humans (for comprehensive reviews of earlier findings, see the most recent reviews on the topic 4-7 ). However, for the purpose of our study, only information related directly to human meibum will be discussed. Earlier, human meibomian WE from normal (nondry eye) and dry eye subjects were studied using gas (or gasliquid) chromatography with flame ionization detection (GC-FID and GLC-FID), and GC-and GLC-mass spectrometry (GCand GLC-MS). MATERIALS AND METHODS Samples of meibum were collected using a protocol described previously 13 and the amounts of collected meibum were measured gravimetrically. All sample collection procedures that involved human subjects were approved by the UT Southwestern Institutional Review Board, and were conducted in accordance with the Declaration of From th

Sex Differences in Becoming a Current Electronic Cigarette User, Current Smoker and Current Dual User of Both Products: A Longitudinal Study Among Mexican Adolescents

This study aimed to assess sex differences in predictors for becoming a current exclusive electronic cigarette (e-cigarette) user, current exclusive smoker, or current dual user (concurrent smoking and e-cigarette use). This longitudinal study included 2399 females and 2177 males who had tried neither cigarettes nor e-cigarettes at baseline and attended 57 middle schools in the three largest cities in Mexico. We estimated multinomial logistic models stratified by sex. At follow-up, the prevalence of current exclusive e-cigarette use was 6.4% for males and 5.5% for females; current exclusive smoking was similar among males (3.6%) and females (3.5%); dual use was 2.4% females and 1.8% males. In the adjusted model, current e-cigarette use among females was associated with baseline current drinking (ARR = 1.85; p \u3c 0.05), having a job (ARR = 1.99; p \u3c 0.05), higher technophilia (ARR = 1.27; p \u3c 0.05), and higher positive smoking expectancies (ARR = 1.39; p \u3c 0.05). Among males, only having friends who smoke cigarettes at baseline was a significant predictor of current exclusive e-cigarette use at follow-up (ARR = 1.44; p \u3c 0.05). For both sexes, current exclusive smoking at follow-up was associated with baseline current drinking (male ARR = 2.56; p \u3c 0.05; female ARR = 2.31; p \u3c 0.05) and, among males, only with having a parent who smoked (ARR = 1.64; p \u3c 0.05). For both sexes, dual use at follow-up was associated with baseline current drinking (male ARR = 3.52; p \u3c 0.005; female ARR = 2.77; p \u3c 0.05); among females, with having paid work (ARR = 2.50; p \u3c 0.001); and among males, with parental smoking (ARR = 3.20; p \u3c 0.05). Results suggested both common and different risk factors by sex, suggesting that interventions may need to consider targeting sex differences

HPV molecular detection from urine versus cervical samples: an alternative for HPV screening in indigenous populations

Background Cervical cancer (CC) is the fourth leading cause of death from neoplasms in women and is caused by the human papilloma virus (HPV). Several methods have been developed for the screening of cervical lesions and HPV; however, some socio-cultural factors prevent women from undergoing gynecological inspection, which results in a higher risk of mortality from cervical cancer in certain population groups as indigenous communities. This study aimed to compare the concordance in HPV detection from urine and cervical samples, to propose an alternative to cervical scraping, which is commonly used in the cervical cancer screening. Methodology The DNA from cervical scrapings and urine samples was extracted using the proteinase K method followed by precipitation with alcohol, phenol andchloroform; a modification of the proteinase K method was developed in the management of urine sediment. Viral genotyping was performed using INNOLipa. Results The study population consisted of 108 patients from an indigenous population at southern Mexico, 32 without squamous intraepithelial lesions (NSIL) and 76 with low squamous intraepithelial lesions (LSIL). The majority of NSIL cervical scrapes were negative for HPV (90.63%), whereas more than half of LSIL cases were high-risk HPV positive (51.32%), followed by multiple infection by HR-HPV (17.11%), and multiple infection by LR- and HR-HPV (9.21%). No statistically significant relationship between the cytological diagnosis and the HPV genotypes detected in the urine samples was observed. A concordance of 68.27% for HPV positivity from urine and cervical samples was observed. Similarly, a concordance of 64.52% was observed in the grouping of HPVs by oncogenic risk. HR-HPV was detected in 71% of the urine samples from women with LSIL diagnosis, which suggests that HR-HPV detected in a urine sample could indicate the presence or risk of developing SIL. Conclusion HR-HPV detection in urine samples could be an initial approach for women at risk of developing LSIL and who, for cultural reasons, refuse to undergo a gynecological inspection

Meibum Lipid Composition in Asians with Dry Eye Disease

10.1371/journal.pone.0024339PLoS ONE610