Work and heat probability distribution of an optically driven Brownian particle: Theory and experiments

We analyze the equations governing the evolution of distributions of the work and the heat exchanged with the environment by a manipulated stochastic system, by means of a compact and general derivation. We obtain explicit solutions for these equations for the case of a dragged Brownian particle in a harmonic potential. We successfully compare the resulting predictions with the outcomes of experiments, consisting in dragging a micron-sized colloidal particle through water with a laser trap

Towards a Typology of Fraterniy/Sorority Programs: A Content Analysis

Fraternity/sorority standards have been represented as the answer to the Call for Values Congruence authored by the Franklin Squared Group (2003). The outcome of this document was a proliferation of various styles and models of standards programs utilized to establish community practices with the overarching goal of facilitating values-based fraternity and sorority campus communities. However, fraternity/sorority standards programs answering this call have established higher standards through different methods. This study solicited standards programs from institutions from across the United States. Data from 31 standards programs were collected, cataloged, and analyzed through qualitative inquiry with the use of a rubric developed to establish a typology. Five categories resulted from analysis: evaluation, minimum standards, accreditation, awards, and comprehensive. Implications of the study are included along with future directions for research

Towards a Typology of Fraterniy/Sorority Programs: A Content Analysis

Fraternity/sorority standards have been represented as the answer to the Call for Values Congruence authored by the Franklin Squared Group (2003). The outcome of this document was a proliferation of various styles and models of standards programs utilized to establish community practices with the overarching goal of facilitating values-based fraternity and sorority campus communities. However, fraternity/sorority standards programs answering this call have established higher standards through different methods. This study solicited standards programs from institutions from across the United States. Data from 31 standards programs were collected, cataloged, and analyzed through qualitative inquiry with the use of a rubric developed to establish a typology. Five categories resulted from analysis: evaluation, minimum standards, accreditation, awards, and comprehensive. Implications of the study are included along with future directions for research

An Examination of Alcohol Expectations and Social Desirability in Fraternity Members on American College Campuses

Males who are members of American college fraternal organizations remain one of the heaviest drinking populations among college students (Wall, 2006). Within fraternities, alcohol use is ceded to social status (Larimer et al., 1997). This culturally ingrained alcohol misuse has confounded interventions and programming to address this phenomenon and response to these attempts have been low or nonexistent by fraternity members. This study investigated alcohol expectations and social desirability among fraternity members. It was hypothesized that as members enter and remain in the fraternity culture, distorted expectations and socially desirable behaviors may occur as demonstrated by differences between pledges and active members. Participants took the Brown et al. (1987) Alcohol Expectancy Questionnaire-Adult version and the Marlowe and Crowne (1964) Social Desirability inventory. Results revealed that pledges engaged in higher levels of socially desirable behaviors and conformed towards exaggerated expectations of alcohol related to overall alcohol use, sexual ability, and socialization. Implications for advisors, health education professionals, college administrators, and counselors are suggested

A simple and reliable approach for the fabrication of nanoporous silver patterns for surface-enhanced Raman spectroscopy applications

The fabrication of plasmonic nanostructures with a reliable, low cost and easy approach has become a crucial and urgent challenge in many fields, including surface-enhanced Raman spectroscopy (SERS) based applications. In this frame, nanoporous metal films are quite attractive, due to their intrinsic large surface area and high density of metal nanogaps, acting as hot-spots for Raman signal enhancement. In this paper, we report a detailed study on the fabrication of nanoporous silver-based SERS substrates, obtained by the application of two successive treatments with an Inductively Coupled Plasma (ICP) system, using synthetic air and Ar as feeding gases. The obtained substrates exhibit a quite broad plasmonic response, covering the Vis–NIR range, and an enhancement factor reaching 6.5 ×107, estimated by using 4-mercaptobenzoic acid (4-MBA) as probe molecule at 532 nm. Moreover, the substrates exhibit a quite good spatial reproducibility on a centimeter scale, which assures a good signal stability for analytical measurements. Globally, the developed protocol is easy and cost effective, potentially usable also for mass production thanks to the remarkable inter-batches reproducibility. As such, it holds promise for its use in SERS-based sensing platforms for sensitive detection of targets molecules

Feasibility of SERS-Active Porous Ag Substrates for the Effective Detection of Pyrene in Water

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous pollutants that are typically released into the environment during the incomplete combustion of fossil fuels. Due to their relevant carcinogenicity, mutagenicity, and teratogenicity, it is urgent to develop sensitive and cost-effective strategies for monitoring them, especially in aqueous environments. Surface-enhanced Raman spectroscopy (SERS) can potentially be used as a reliable approach for this purpose, as it constitutes a valid alternative to traditional techniques, such as liquid and gas chromatography. Nevertheless, the development of an SERS-based platform for detection PAHs has so far been hindered by the poor adsorption of PAHs onto silver-and gold-based SERS-active substrates. To overcome this limitation, several research efforts have been directed towards the development of functionalized SERS substrates for the improvement of PAH adsorption. However, these strategies suffer from the interference that functionalizing molecules can produce in SERS detection. Herein, we demonstrate the feasibility of label-free detection of pyrene by using a highly porous 3D-SERS substrate produced by an inductively coupled plasma (ICP). Thanks to the coral-like nanopattern exhibited by our substrate, clear signals ascribable to pyrene molecules can be observed with a limit of detection of 23 nM. The observed performance can be attributed to the nanoporous character of our substrate, which combines a high density of hotspots and a certain capability of trapping molecules and favoring their adhesion to the Ag nanopattern. The obtained results demonstrate the potential of our substrates as a large-area, label-free SERS-based platform for chemical sensing and environmental control applications

Nanoporous silver films produced by solid-state dewetting for SERS applications

Detection of analytes in aqueous solution with high specificity and sensitivity is of paramount importance in many fields of science, ranging from biomedicine, environmental control, and food quality assessment. Surface-enhanced Raman scattering (SERS) has proven to be a cutting-edge analytical technique for this purpose, by combining the high selectivity of Raman features with the high sensitivity deriving from the plasmonic amplification of Raman signals. Herein, we report a facile and quite effective approach to fabricate large-area Ag-based SERS substrates, exhibiting a porous, coral-like nanotexture. Due to their intrinsic large surface-area and high hot-spot density, the produced substrates appear quite promising for the detection of analytes at trace levels. The nanoporous substrates are produced by Solid-State Dewetting (SSD) of thin Ag-films. In particular, ~30 nm thickness Ag-films are first deposited on glass coverslips by magnetron sputtering. Then, marked roughening is induced by exposing the films to an Inductively Coupled Plasma (ICP) discharge, using synthetic air as feeding gas. The performances of our SERS substrates are characterized in terms of morphology and enhancement factor using CV as probe molecule

Differences in Informal Alcohol Protective Behavior Strategies between Fraternity & Sorority Members

Institutional interventions and formal policies designed to reduce alcohol misuse among fraternity and sorority members have been largely unsuccessful. However, informal policies to address alcohol use concerns can also develop within this subculture. This qualitative multi-case phenomenological study examined the informal policies chapters adopt to reduce risks associated with drinking. Findings suggested considerable informal policy development, which varies between fraternities and sororities. Sorority groups implemented more protective behavior strategies for members’ safety, whereas fraternities often focus on monitoring outside groups. Implications for practice suggest a combination of risk and harm-reduction approaches that facilitate peer-led protective behavioral strategies

Direct calorimetric measurements of isothermal entropy change on single crystal W-type hexaferrites at the spin reorientation transition

We report on the magnetic field induced isothermal entropy change, \Delta s(Ha, T), of W-type ferrite with CoZn substitution. Entropy measurements are performed by direct calorimetry. Single crystals of the composition BaCo$_0.62$Zn$_1.38$Fe$_16$O$_27$, prepared by the flux method, are measured at different fixed temperatures under an applied field perpendicular and parallel to the c axis. At 296 K one deduces a value of K$_1$ = 8.7 \times 10^{4} J m$^-3$ for the first anisotropy constant, which is in good agreement with the literature. The spin reorientation transition temperature is estimated to take place between 200 and 220 K

Investigating Eusociality in Bees while Trusting the Uncertainty

Phylogenetic hypotheses and estimates of divergence times have already been used to investigate the evolution of social behavior in all lineages of bees. The interpretation of the number of origins of eusocial behavior and the timing these events depends on reliable phylogenetic hypotheses for the clades in which these lineages are nested. Three to six independent origins of eusocial behavior are interpreted to have occurred in bee taxa that differentiated in the Late Cretaceous, or much later in the Paleogene. Only two groups of bees exhibit the behaviors that qualify their members to be considered obligate eusocial, the honey bees (Apina) and the stingless bees (Meliponina). The evolutionary history of corbiculate bees remains uncertain in many respects, but phylogenetic research has been paving the path for comprehensive comparative approaches likely to shed light on the origin of diversity of forms and behaviors of these bees. In total, corbiculate bees encompass about 1000 species, roughly 5% of the described species diversity of bees. These bees are rather heterogeneous in terms of social organization, particularly stingless bees and orchid bees, which display a fascinating range of behavioral variation. Using phylogenetic tools, it has been possible to infer that caste polymorphism, division of labor and other traits of corbiculate bees probably started evolving over 80 million years ago. Phylogenetic hypotheses must be interpreted as more or less uncertain scenarios for studying the biological diversity, but when trusted they can provide powerful tools to investigate the evolution of social behaviors