Hot-pressing process modeling for medium density fiberboard (MDF)

In this paper we present a numerical solution for the mathematical modeling of the hot-pressing process applied to medium density fiberboard. The model is based in the work of Humphrey[82], Humphrey and Bolton[89] and Carvalho and Costa[98], with some modifications and extensions in order to take into account mainly the convective effects on the phase change term and also a conservative numerical treatment of the resulting system of partial differential equations.Comment: LaTeX, 11 figures. Added references. Fixed some errors. To appear in International Journal of Mathematics and Mathematical Sciences, http://jam.hindawi.co

Coronal heating in coupled photosphere-chromosphere-coronal systems: turbulence and leakage

Coronal loops act as resonant cavities for low frequency fluctuations that are transmitted from the deeper layers of the solar atmosphere and are amplified in the corona, triggering nonlinear interactions. However trapping is not perfect, some energy leaks down to the chromosphere, thus limiting the turbulence development and the associated heating. We consider the combined effects of turbulence and leakage in determining the energy level and associated heating rate in models of coronal loops which include the chromosphere and transition region. We use a piece-wise constant model for the Alfven speed and a Reduced MHD - Shell model to describe the interplay between turbulent dynamics in the direction perpendicular to the mean field and propagation along the field. Turbulence is sustained by incoming fluctuations which are equivalent, in the line-tied case, to forcing by the photospheric shear flows. While varying the turbulence strength, we compare systematically the average coronal energy level (E) and dissipation rate (D) in three models with increasing complexity: the classical closed model, the semi-open corona model, and the corona-chromosphere (or 3-layer) model, the latter two models allowing energy leakage. We find that: (i) Leakage always plays a role (even for strong turbulence), E and D are systematically lower than in the line-tied model. (ii) E is close to the resonant prediction, i.e., assuming effective turbulent correlation time longer than the Alfven coronal crossing time (Ta). (iii) D is close to the value given by the ratio of photospheric energy divided by Ta (iv) The coronal spectra exibits an inertial range with 5/3 spectral slope, and a large scale peak of trapped resonant modes that inhibit nonlinear couplings. (v) In the realistic 3-layer model, the two-component spectrum leads to a damping time equal to the Kolmogorov time reduced by a factor u_rms/Va_coronaComment: 15 pages, 15 figures, Accepted for publication in A&

Effect of wind gusts on the motion of a balloon-borne observation platform

The effect of wind gusts on the magnitude of the pendulation angles of a balloon-borne observation platform is determined. A system mathematical model is developed and the solution of this model is used to determine the magnitude of the observation platforms pendulation angles

A Comprehensive Reentry Policy for Student Registered Nurse Anesthetists with Substance Use Disorder

Substance use disorder (SUD) is a common problem in anesthesia. While there are policies in place for practicing anesthetists, there are no known studies to date discussing reentry policies specific to the student registered nurse anesthesia (SRNA) population. The purpose of this research study was to describe key stakeholders’ knowledge and perspectives surrounding policies for reentry into academic programs for SRNAs in Illinois with SUD. The theoretical framework used to drive this research was based off George L. Engel’s Biopsychosocial Theory. The theory examines the biological component of a person’s disease process, the psychological component, and the social component. During November 2017-January 2018, qualitative interviews were conducted using a semi-structured interview guide with chief anesthesiologists, chief certified registered nurse anesthetists (CRNAs), and directors of academic anesthesia programs from throughout Illinois. All interviews were audio recorded, transcribed, and analyzed using thematic analysis. Eleven major themes were identified: existent and non-existent SUD policies, inconsistent methods on how to access a policy, variability in the components of SUD policies, difficulty in determining SUD among SRNAs, difficulty in confronting an individual, effectiveness of components of SUD policies are equivocal, ineffective components of a policy, knowing a person with SUD is not uncommon, variable amount of time needed for SUD treatment, differing opinions for the need for a student specific SUD policy, and reasons for need. The immediate goal of this research was to create a comprehensive reentry policy for SRNAs in Illinois with SUD to provide a structured reentry into an academic program. The long-term goal was to provide a tool that could be utilized in all academic anesthesia programs to assist all students suffering from SUD. All institutions that educate and utilize SRNAs should have a comprehensive reentry policy in place for SRNAs with SUD, which includes SRNA reentry to their educational program

Distribution and Diversity of Bacterial Chemolithotrophs in Marine and Freshwater Sediments

Bacterial chemolithotroph population structure has been investigated in Lowes Cove marine intertidal mudflat and Damariscotta Lake, Maine. A 492 to 495 fragment of the cbbL gene, coding for the large subunit of Form I ribulose-1,5- bisphosphate carboxylase/oxygenase (rubisco) was amplified from lake surface (upper 2 mm) sediments and mudflat surface (upper 2 mm), subsurface (5-7 cm), and Mya arenaria burrow wall sediments, as well as sulfide-oxidizing bacterial mat samples. Amplified DNA was used to construct cbbL clone libraries. Phylogenetic analysis showed that Damariscotta Lake cbbL clones were mainly of the 1C type, indicating a facultative carbon monoxide/hydrogen-oxidizing community. Conversely, clones constructed from Lowes Cove sediments were dominated by Form 1A cbbL-containing chemolithotrophs that were most closely related to cbbL genes of sulfur-oxidizing bacteria. This suggested that the chemolithotroph community structure in lake sediments differs greatly from marine sediments. Phylogenetic P-tests of Lowes Cove sediments indicated that surface, subsurface and burrow wall sediments contain significant phylogenetic differences. AMOVA and LIBSHUFF statistical analyses of Lowes Cove sediment cbbL libraries suggested that Mya arenaria burrow wall sediments did not harbor distinct communities when compared to mudflat surface and subsurface libraries. However, Lowes Cove surface and subsurface cbbL libraries displayed moderate genetic difference by AMOVA analyses and were observed to contain distinct chemolithotroph communities by LIBSHUFF analysis of homologous and heterologous coverages

The Influence of Bureau Scores, Customized Scores and Judgmental Review on the Bank Underwriting Decision-Making Process

In recent years commercial banks have moved toward automated forms of underwriting. This study employs unique bank loan-level data from a scoring lender to determine whether automated underwriting exhibits a potential ‘‘disparate impact’’ across income strata. The findings indicate that strict application of this custom scoring model leads to higher denial rates for low- to moderate-income borrowers when compared with both a naý¨ve judgmental system and a bureau scoring approach. These results suggest that financial regulators should focus more resources on the evaluation and study of customized scoring models.

Integrals of Motion for Critical Dense Polymers and Symplectic Fermions

We consider critical dense polymers ${\cal L}(1,2)$. We obtain for this model the eigenvalues of the local integrals of motion of the underlying Conformal Field Theory by means of Thermodynamic Bethe Ansatz. We give a detailed description of the relation between this model and Symplectic Fermions including the indecomposable structure of the transfer matrix. Integrals of motion are defined directly on the lattice in terms of the Temperley Lieb Algebra and their eigenvalues are obtained and expressed as an infinite sum of the eigenvalues of the continuum integrals of motion. An elegant decomposition of the transfer matrix in terms of a finite number of lattice integrals of motion is obtained thus providing a reason for their introduction.Comment: 53 pages, version accepted for publishing on JSTA

Emergence, molecular mechanisms and global spread of carbapenem-resistant acinetobacter baumannii

© 2019 The Authors. Acinetobacter baumannii is a nosocomial pathogen that has emerged as a global threat because of high levels of resistance to many antibiotics, particularly those considered to be last-resort antibiotics, such as carbapenems. Although alterations in the efflux pump and outer membrane proteins can cause carbapenem resistance, the main mechanism is the acquisition of carbapenem-hydrolyzing oxacillinase-encoding genes. Of these, oxa23 is by far the most widespread in most countries, while oxa24 and oxa58 appear to be dominant in specific regions. Historically, much of the global spread of carbapenem resistance has been due to the dissemination of two major clones, known as global clones 1 and 2, although new lineages are now common in some parts of the world. The analysis of all publicly available genome sequences performed here indicates that ST2, ST1, ST79 and ST25 account for over 71% of all genomes sequenced to date, with ST2 by far the most dominant type and oxa23 the most widespread carbapenem resistance determinant globally, regardless of clonal type. Whilst this highlights the global spread of ST1 and ST2, and the dominance of oxa23 in both clones, it could also be a result of preferential selection of carbapenem-resistant strains, which mainly belong to the two major clones. Furthermore, ~70% of the sequenced strains have been isolated from five countries, namely the USA, PR China, Australia, Thailand and Pakistan, with only a limited number from other countries. These genomes are a vital resource, but it is currently difficult to draw an accurate global picture of this important superbug, highlighting the need for more comprehensive genome sequence data and genomic analysis

Resonant Characteristics of Rectangular Microcantilevers Vibrating Torsionally in Viscous Liquid Media

The resonant characteristics of rectangular microcantilevers vibrating in the torsional mode in viscous liquid media are investigated. The hydrodynamic load (torque per unit length) on the vibrating beam due to the liquid was first determined using a finite element model. An analytical expression of the hydrodynamic function in terms of the Reynolds number and aspect ratio, h/b (with thickness, h, and width, b) was then obtained by fitting the numerical results. This allowed for the resonance frequency and quality factor to be investigated as functions of both beam geometry and medium properties. Moreover, the effects of the aspect ratio on the cross-section\u27s torsional constant, K, which affects the microcantilever\u27s torsional stiffness, and on its polar moment of inertia, Jp, which is associated with the beam\u27s rotational inertia, are also considered when obtaining the resonance frequency and quality factor. Compared with microcantilevers under out-of-plane (transverse) flexural vibration, the results show that microcantilevers that vibrate in their 1st torsional or 1st in-plane (lateral) flexural resonant modes have higher resonance frequency and quality factor. The increase in resonance frequency and quality factor results in higher mass sensitivity and reduced frequency noise, respectively. The improvement in the sensitivity and quality factor are expected to yield much lower limits of detection in liquid-phase chemical sensing applications

Resonant Characteristics of Rectangular Hammerhead Microcantilevers Vibrating Laterally in Viscous Liquid Media

The resonant characteristics of laterally vibrating rectangular hammerhead microcantilevers in viscous liquid media are investigated. The rectangular hammerhead microcantilever is modeled as an Euler-Bernoulli beam (stem) and a rigid body (head). A modified semi-analytical expression for the hydrodynamic function in terms of the Reynolds number, Re, and aspect ratio, h/b, is proposed to rapidly evaluate the sensing characteristics. Using this expression, the resonance frequency, quality factor and normalized surface mass sensitivity are investigated as a function of the dimensions of the microcantilever and liquid properties. Guidelines for design of hammerhead microcantilever geometry are proposed to achieve efficient sensing platforms for liquid-phase operation. The improvement in the sensing area and characteristics are expected to yield higher sensitivity of detection and improved signal-to-noise ratio in liquid-phase chemical sensing applications