Particle Focusing in Microchannels

The ability to control the motion of particles and cells in microchannels has been a center of fascination since the advent of microfluidics. Entire fields have been created in order to accomplish separation, volume reduction and overall positioning of particles and cells within microfluidic devices in the fastest and most accurate manner possible. While most of these technologies rely on low Reynolds number operation, one technique entitled inertial focusing takes advantage of the inertia of the surrounding fluid and the interaction between a particle and the channel itself which cause the lateral migration of particles across streamlines to equilibrium positions within a flow. The major advantage of inertial microfluidics in biomedical and microfluidic applications is that it is inherently high throughput being dependent on inertia whereas most microfluidic concepts are dependent on low Reynolds number operation.Engineering and Applied Science

Anxiety and Depression as Comorbid Factors in Drinking Behaviors of Undergraduate College Students Attending an Urban Private University in the Northeastern United States

High-risk drinking is the number one public health concern on college campuses (Berkowitz, 2003; Kapner, 2003; Wechsler, 2002). To date, high-risk drinking prevention programs have met with limited success (Kapner, 2003). This study examined differences among four drinking behavior groups: non-drinkers [(ND), (n = 128)], low-risk drinkers [(LRD), (n = 252)], high-risk drinkers [(HRD), (n = 272)], and frequent high-risk drinkers [(FHRD), (n = 290)] with respect to anxiety and depression for male (n = 457) and female (n = 485) undergraduates (N = 942) attending an urban private university in the northeastern United States; and, the perceptions of two undergraduate focus groups (N = 10) and one faculty/staff group (N = 14) for why undergraduates engage in high-risk drinking and actions to reduce this behavior. Volunteer participants completed a demographic questionnaire, the Alcohol Use Disorders Identification Test, the Beck Anxiety Inventory, and the Beck Depression Inventory. An ANOVA indicated differences among the groups with respect to anxiety (F = 6.49, p \u3c .001), but not with respect to depression. The FHRD group had higher anxiety (M = .68) than the ND group (M = .33) and the LRD group (M = .44). A t-test indicated differences (p \u3c .01) in the level of anxiety between HRD females (M = .69) and HRD males (M = .40), with no differences for depression. A chi-square analysis indicated differences between males and females with respect to drinking behavior group classification (χ² = 22.40, df = 3, p = .001). Focus group results suggested several reasons why students engage in high-risk drinking: it is the norm, easy access to alcohol, low accountability for drinking, cope with anxiety, relieve boredom, lift depression, cope with anger, family history of alcohol use, alcohol dependence, and poor self-esteem. Implications for educators are discussed

Las mermas y la rentabilidad en la Panificadora Torres S.A.C., Lurigancho-Chosica 2023

La tesis aborda el impacto de las mermas en la rentabilidad de la Panificadora Torres S.A.C. en Lurigancho-Chosica, Perú 2023. La metodología que se empleó en la investigación es básica, se utilizó un diseño no experimental que se aplicó de manera transversal, con un enfoque cuantitativo y se utilizó la recolección y el análisis de datos. La técnica que se empleó fue el análisis documental y el instrumento fue la ficha documental. La población de la investigación fue el registro de mermas del sistema Torres correspondiente al año 2023 y documentos financieros de la panificadora Torres 2023, teniendo como muestra la plantilla de las mermas de la empresa Torres del 2023 y estado financiero de la panificadora Torres 2023. Se concluyó que las mermas si inciden de manera significativa en la rentabilidad de la panificadora Torres SAC en Lurigancho- Chosica 2023

Actuación de las entidades persecutoras de los delitos informáticos en pandemia por COVID-19

Esta presente tesis, tuvo como objetivo general determinar si la actuación de las entidades persecutoras de los delitos informáticos fueron las adecuadas durante pandemia por covid-19, en tal sentido se tomó antecedes nacionales e internacionales y dos teorías bases a fin proponer posibles soluciones al problema que es materia de investigación teniéndose en cuenta la experticia de los entrevistados, quienes laboran en el Ministerio Publico, División de Investigación de Delitos de Alta Tecnología (DIVINDAT) y una letrada independiente. Por otro lado, se destaca que la presente tesis es de enfoque cualitativo de tipo base, con diseño fenomenológico y de método inductivo, teniendo como herramienta de investigación para el procesamiento de análisis datos el programa ATLAS.ti 9. Finalmente, se evidencio en la tesis problemas como la falta de personal capacitado en ambos órganos, así también, la insuficiencia de herramientas digitales y tecnológicos para llevar a cabo una correcta investigación; y finalmente cursos, capacitación por parte del Gobierno Peruano a todo el personal, pues a raíz de la pandemia la Fiscalía Especializada en Ciberdelincuencia y la Divindat no se abastece ante la indagación de los delitos informáticos

The Type Ic Supernova 1994I in M51: Detection of Helium and Spectral Evolution

We present a series of spectra of SN 1994I in M51, starting 1 week prior to maximum brightness. The nebular phase began about 2 months after the explosion; together with the rapid decline of the optical light, this suggests that the ejected mass was small. Although lines of He I in the optical region are weak or absent, consistent with the Type Ic classification, we detect strong He I λ10830 absorption during the first month past maximum. Thus, if SN 1994I is a typical Type Ic supernova, the atmospheres of these objects cannot be completely devoid of helium. The emission-line widths are smaller than predicted by the model of Nomoto and coworkers, in which the iron core of a low-mass carbon-oxygen star collapses. They are, however, larger than in Type Ib supernovae

Existence and regularity of extremal solutions for a mean-curvature equation

We study a class of mean curvature equations $-\mathcal Mu=H+\lambda u^p$ where $\mathcal M$ denotes the mean curvature operator and for $p\geq 1$. We show that there exists an extremal parameter $\lambda^*$ such that this equation admits a minimal weak solutions for all $\lambda \in [0,\lambda^*]$, while no weak solutions exists for $\lambda >\lambda^*$ (weak solutions will be defined as critical points of a suitable functional). In the radially symmetric case, we then show that minimal weak solutions are classical solutions for all $\lambda\in [0,\lambda^*]$ and that another branch of classical solutions exists in a neighborhood $(\lambda_*-\eta,\lambda^*)$ of $\lambda^*$.Comment: v2: Typos corrected. Proof of Theorem 2.11 added

The critical dimension for a 4th order problem with singular nonlinearity

We study the regularity of the extremal solution of the semilinear biharmonic equation \bi u=\f{\lambda}{(1-u)^2}, which models a simple Micro-Electromechanical System (MEMS) device on a ball B\subset\IR^N, under Dirichlet boundary conditions $u=\partial_\nu u=0$ on $\partial B$. We complete here the results of F.H. Lin and Y.S. Yang \cite{LY} regarding the identification of a "pull-in voltage" \la^*>0 such that a stable classical solution u_\la with 0 exists for \la\in (0,\la^*), while there is none of any kind when \la>\la^*. Our main result asserts that the extremal solution $u_{\lambda^*}$ is regular $(\sup_B u_{\lambda^*} <1)$ provided $N \le 8$ while $u_{\lambda^*}$ is singular ($\sup_B u_{\lambda^*} =1$) for $N \ge 9$, in which case $1-C_0|x|^{4/3}\leq u_{\lambda^*} (x) \leq 1-|x|^{4/3}$ on the unit ball, where $C_0:= (\frac{\lambda^*}{\overline{\lambda}})^{1/3}$ and $\bar{\lambda}:= {8/9} (N-{2/3}) (N- {8/3})$.Comment: 19 pages. This paper completes and replaces a paper (with a similar title) which appeared in arXiv:0810.5380. Updated versions --if any-- of this author's papers can be downloaded at this http://www.birs.ca/~nassif

Three-Dimensional Holographic Refractive-Index Measurement of Continuously Flowing Cells in a Microfluidic Channel

The refractive index of biological specimens is a source of intrinsic contrast that can be explored without any concerns of photobleaching or harmful effects caused by extra contrast agents. In addition, the refractive index contains rich information related to the metabolism of cells at the cellular and subcellular levels. Here, we report a no-moving-parts approach that provides three-dimensional refractive-index maps of biological samples continuously flowing in a microfluidic channel. Specifically, we use line illumination and off-axis digital holography to record the angular spectra of light scattered from flowing samples at high speed. Applying the scalar diffraction theory, we obtain accurate refractive-index maps of the samples from the measured spectra. Using this method, we demonstrate label-free three-dimensional imaging of live RKO human colon cancer cells and RPMI8226 multiple myeloma cells, and obtain the volume, dry mass, and density of these cells from the measured three-dimensional refractive-index maps. Our results show that the reported method, alone or in combination with the existing flow cytometry techniques, shows promise as a quantitative tool for stain-free characterization of a large number of cells.National Institutes of Health (U.S.) (9P41EB015871-26A1)National Institutes of Health (U.S.) (P41 EB002503)Hamamatsu Corporatio

Investigation of amphibian mortality events in wildlife reveals an on-going ranavirus epidemic in the North of the Netherlands

In the four years following the first detection of ranavirus (genus Ranavirus, family Iridoviridae) infection in Dutch wildlife in 2010, amphibian mortality events were investigated nationwide to detect, characterize and map ranaviruses in amphibians over time, and to establish the affected host species and the clinico-pathological presentation of the disease in these hosts. The ultimate goal was to obtain more insight into ranavirus disease emergence and ecological risk. In total 155 dead amphibians from 52 sites were submitted between 2011 and 2014, and examined using histopathology, immunohistochemistry, virus isolation and molecular genetic characterization. Ranavirus-associated amphibian mortality events occurred at 18 sites (35%), initially only in proximity of the 2010 index site. Specimens belonging to approximately half of the native amphibian species were infected, including the threatened Pelobates fuscus (spadefoot toad). Clustered massive outbreaks involving dead adult specimens and ranavirus genomic identity indicated that one common midwife toad virus (CMTV)-like ranavirus strain is emerging in provinces in the north of the Netherlands. Modelling based on the spatiotemporal pattern of spread showed a high probability that this emerging virus will continue to be detected at new sites (the discrete reproductive power of this outbreak is 0.35). Phylogenetically distinct CMTV-like ranaviruses were found in the south of the Netherlands more recently. In addition to showing that CMTV-like ranaviruses threaten wild amphibian populations not only in Spain but also in the Netherlands, the current spread and risk of establishment reiterate that understanding the underlying causes of CMTV-like ranavirus emergence requires international attention

The Effective Field Theory of Cosmological Large Scale Structures

Large scale structure surveys will likely become the next leading cosmological probe. In our universe, matter perturbations are large on short distances and small at long scales, i.e. strongly coupled in the UV and weakly coupled in the IR. To make precise analytical predictions on large scales, we develop an effective field theory formulated in terms of an IR effective fluid characterized by several parameters, such as speed of sound and viscosity. These parameters, determined by the UV physics described by the Boltzmann equation, are measured from N-body simulations. We find that the speed of sound of the effective fluid is c_s^2 10^(-6) and that the viscosity contributions are of the same order. The fluid describes all the relevant physics at long scales k and permits a manifestly convergent perturbative expansion in the size of the matter perturbations \delta(k) for all the observables. As an example, we calculate the correction to the power spectrum at order \delta(k)^4. The predictions of the effective field theory are found to be in much better agreement with observation than standard cosmological perturbation theory, already reaching percent precision at this order up to a relatively short scale k \sim 0.24 h/Mpc.Comment: v2: typos corrected, JHEP published versio