Mid-infrared upconversion spectroscopy based on a Yb:fiber femtosecond laser

We present a system for molecular spectroscopy using a broadband mid-infrared laser with near infrared detection. Difference frequency generation of a Yb:fiber femtosecond laser produced a mid-infrared (MIR) source tunable from 2100-3700 cm^-1 (2.7-4.7 microns) with average power up to 40 mW. The MIR spectrum was upconverted to near-infrared wavelengths for broadband detection using a two-dimensional dispersion imaging technique. Absorption measurements were performed over bandwidths of 240 cm^-1 (7.2 THz) with 0.048 cm^-1 (1.4 GHz) resolution, and absolute frequency scale uncertainty was better than 0.005 cm^-1 (150 MHz). The minimum detectable absorption coefficient per spectral element was determined to be 4.4 x 10^-7 cm^-1 from measurements in low pressure CH_4, leading to a detection limit of 2 parts-per-billion. The spectral range, resolution, and frequency accuracy of this system show promise for determination of trace concentrations in gas mixtures containing both narrow and broad overlapping spectral features, and we demonstrate this in measurements of air and solvent samples.Comment: 8 pages, 7 figure

Narratives from Appalachia: The Current Stories of LGBTQ Community College Students

LGBTQ students are ubiquitous on community college campuses across the United States. The exact number of LGBTQ students is unknown and often their needs are ignored. LGBTQ students face harassment and discrimination at higher rates than other minority groups. This study was conducted to gather the current narratives of LGBTQ students attending community colleges in the Appalachian Region. This study aimed to determine what LGBTQ students are experiencing on community college campuses across Appalachia. Fifteen students took part in a one-on-one semi-structured interview for this qualitative study. All students were currently enrolled in a program of study when the interviews took place. The research paradigm utilized was social constructivism, and Queer Theory was the basis of the conceptual framework. This study used narrative coding with the Labovian Model of Analysis. Composite narratives were written, and pseudonyms used to create anonymity for the participants. The findings of this study indicated students encounter microaggressions in the classroom and in other places around a community college. Nevertheless, the campus is often perceived to be a cultural bubble by students and is perceived as safer than the nearest town or city. Participants stated that the religious views of other students often impact the lives of LGBTQ students. Additionally, participants mentioned politics and how it affected their lives as community college students

Ending “Too Big To Fail”: Government Promises Versus Investor Perceptions

Can a government credibly promise not to bailout firms whose failure would have major negative systemic consequences? Our analysis of Korea’s 1997–98 crisis suggests an answer: No. Despite a general “no bailout” policy during the crisis, the largest Korean corporate groups—facing severe financial and governance problems—could still borrow heavily from households by issuing bonds at prices implying very low expected default risk. The evidence suggests “too big to fail” beliefs were not eliminated by government promises because investors believed that this policy was not time consistent. Subsequent bailouts confirmed the market view that creditors would be protected

High-power broadband laser source tunable from 3.0 μm to 4.4 μm based on a femtosecond Yb:fiber oscillator

We describe a tunable broadband mid-IR laser source based on difference-frequency mixing of a 100 MHz femto second Yb:fiber laser oscillator and a Raman-shifted soliton generated with the same laser. The resulting light is tunable over 3.0 μm to 4.4 μm, with a FWHM bandwidth of 170 nm and maximum average output power up to 125 mW. The noise and coherence properties of this source are also investigated and described

The accuracy and accessibility of cited evidence: a study examining mental health policy documents

PURPOSE: Evidence-based policy making is increasingly being advocated by governments and scholars. To show that policies are informed by evidence, policy-related documents that cite external sources should ideally provide direct access to, and accurately represent, the referenced source and the evidence it provides. Our aim was to find a way to systematically assess the prevalence of referencing accuracy and accessibility issues in referenced statements selected from a sample of mental health-related policy documents. METHOD: 236 referenced statements were selected from 10 mental health-related policy documents published between 2013 and 2018. Policy documents were chosen as the focus of this investigation because of their relative accessibility and impact on clinical practice. Statements were rated against their referenced sources in terms of the (i) content accuracy in relation to the information provided by the referenced source and (ii) degree of accessibility of the source and the required evidence from the references provided. RESULTS: Of the 236 statements, 41 (59.7%) accurately represented the referenced source, 45 (19.1%) contained major errors and 50 (21.2%) contained minor errors in accuracy. For accessibility, 126 (53.4%) directly referenced primary sources of evidence that supported the claims made, 36 (15.3%) contained indirect references, 18 (7.6%) provided 'dead-end' references, and 11 (4.7%) references were completely inaccessible. CONCLUSIONS: With only slightly over half of all statements assessed providing fully accessible references and accurately representing the referenced source, these components of referencing quality deserve further attention if evidence-informed policy goals are to be achieved. The rating framework used in the current study proved to be a simple and straightforward method to assess these components and can provide a baseline against which interventions can be designed to improve referencing quality

Kinetochore Attachments Require an Interaction between Unstructured Tails on Microtubules and Ndc80Hec1

SummaryKinetochore attachments to microtubules are tight enough to move chromosomes, yet the microtubules' plus ends must remain dynamic and reposition within the attachment pocket during depolymerization-coupled movement. Kinetochores are unable to bind microtubules after any of the four subunits of the Ndc80 complex are knocked down [2, 4]; however, because the Ndc80 complex has important structural roles [1–3], it is unclear whether it directly mediates kinetochore-microtubule attachments. The Ndc80Hec1 subunit (Hec1) has a microtubule-binding site composed of both an unstructured N-terminal tail and a calponin homology domain [5–7]. Here, we show that, surprisingly, the N-terminal tail is sufficient for microtubule-binding affinity in vitro. The interaction is salt sensitive, and the positively charged Hec1 tail cannot bind microtubules lacking negatively charged tails. We have replaced the endogenous Hec1 subunit with a mutant lacking the N-terminal tail. These cells assemble kinetochores properly but are unable to congress chromosomes, generate tension across sister kinetochores, or establish cold-stable kinetochore-microtubule attachments. Our data argue that the highest affinity interactions between kinetochores and microtubules are ionic attractions between two unstructured domains. We discuss the importance of this finding for models of repositioning of microtubules in the kinetochore during depolymerization

Ending "Too Big To Fail": Government Promises vs. Investor Perceptions

Can a government credibly promise not to bailout firms whose failure would have major negative systemic consequences? Our analysis of Korea's 1997-99 crisis, suggests an answer: No. Despite a general "no bailout" policy during the crisis, the largest Korean corporate groups (chaebol) – facing severe financial and governance problems – could still borrow heavily from households through issuing bonds at prices implying very low expected default risk. The evidence suggests "too big to fail" beliefs were not eliminated by government promises, presumably because investors believed that this policy was not time consistent. Subsequent government handling of potential and actual defaults by Daewoo and Hyundai confirmed the market view that creditors would be protected.

Mid-Infrared Optical Frequency Combs based on Difference Frequency Generation for Molecular Spectroscopy

Mid-infrared femtosecond optical frequency combs were produced by difference frequency generation of the spectral components of a near-infrared comb in a 3-mm-long MgO:PPLN crystal. We observe strong pump depletion and 9.3 dB parametric gain in the 1.5 \mu m signal, which yields powers above 500 mW (3 \mu W/mode) in the idler with spectra covering 2.8 \mu m to 3.5 \mu m. Potential for broadband, high-resolution molecular spectroscopy is demonstrated by absorption spectra and interferograms obtained by heterodyning two combs.Comment: 11 pages, 8 figure