9,496 research outputs found
A Method for Greatly Reduced Edge Effects and Crosstalk in CCT Magnets
Iron-free CCT magnet design offers many advantages, one being the excellent
field quality and the absence of multipole components. However, edge effects
are present, although they tend to integrate out over the length of the magnet.
Many modern accelerator applications, however, require that these magnets are
placed in an area of rapidly varying optics parameters, so magnets with greatly
reduced edge effects have an advantage. We have designed such a magnet (a
quadrupole) by adding multipole components of the opposite sign to the edge
distortions of the magnet. A possible application could be the final focus
magnets of the FCC-ee, where beam sizes at the entry and exit point of the
magnets vary by large factors. We have then used this technique to effectively
eliminate cross talk between adjacent final focus quadrupoles for the incoming
and outgoing beams.Comment: Poster presented at MT25,25th International Conference on Magnet
Technology, Amsterdam, August 27 - September 1, 201
Neutron Star Mergers Are the Dominant Source of the r-process in the Early Evolution of Dwarf Galaxies
There are many candidate sites of the r-process: core-collapse supernovae
(including rare magnetorotational core-collapse supernovae), neutron star
mergers, and neutron star/black hole mergers. The chemical enrichment of
galaxies---specifically dwarf galaxies---helps distinguish between these
sources based on the continual build-up of r-process elements. This technique
can distinguish between the r-process candidate sites by the clearest
observational difference---how quickly these events occur after the stars are
created. The existence of several nearby dwarf galaxies allows us to measure
robust chemical abundances for galaxies with different star formation
histories. Dwarf galaxies are especially useful because simple chemical
evolution models can be used to determine the sources of r-process material. We
have measured the r-process element barium with Keck/DEIMOS medium-resolution
spectroscopy. We present the largest sample of barium abundances (almost 250
stars) in dwarf galaxies ever assembled. We measure [Ba/Fe] as a function of
[Fe/H] in this sample and compare with existing [alpha/Fe] measurements. We
have found that a large contribution of barium needs to occur at more delayed
timescales than core-collapse supernovae in order to explain our observed
abundances, namely the significantly more positive trend of the r-process
component of [Ba/Fe] vs. [Fe/H] seen for [Fe/H] <~ -1.6 when compared to the
[Mg/Fe] vs. [Fe/H] trend. We conclude that neutron star mergers are the most
likely source of r-process enrichment in dwarf galaxies at early times.Comment: Accepted to ApJ on 2018 October 2
The theory of the exponential differential equations of semiabelian varieties
The complete first order theories of the exponential differential equations
of semiabelian varieties are given. It is shown that these theories also arises
from an amalgamation-with-predimension construction in the style of Hrushovski.
The theory includes necessary and sufficient conditions for a system of
equations to have a solution. The necessary condition generalizes Ax's
differential fields version of Schanuel's conjecture to semiabelian varieties.
There is a purely algebraic corollary, the "Weak CIT" for semiabelian
varieties, which concerns the intersections of algebraic subgroups with
algebraic varieties.Comment: 53 pages; v3: Substantial changes, including a completely new
introductio
The Desktop Muon Detector: A simple, physics-motivated machine- and electronics-shop project for university students
This paper describes an undergraduate-level physics project that incorporates
various aspects of machine- and electronics-shop technical development. The
desktop muon detector is a self-contained apparatus that employs plastic
scintillator as a detection medium and a silicon photomultiplier for light
collection. These detectors can be used in conjunction with the provided
software to make interesting physics measurements. The total cost of each
counter is approximately $100.Comment: 29 pages, 14 figure
Absorption spectrum in the wings of the potassium second resonance doublet broadened by helium
We have measured the reduced absorption coefficients occurring in the wings
of the potassium 4S-5P doublet lines at 404.414 nm and at 404.720 nm broadened
by helium gas at pressures of several hundred Torr. At the experimental
temperature of 900 K, we have detected a shoulder-like broadening feature on
the blue wing of the doublet which is relatively flat between 401.8 nm and
402.8 nm and which drops off rapidly for shorter wavelengths, corresponding to
absorption from the X doublet Sigma+ state to the C doublet Sigma+ state of the
K-He quasimolecule. The accurate measurements of the line profiles in the
present work will sharply constrain future calculations of potential energy
surfaces and transition dipole moments correlating to the asymptotes He-K(5p),
He-K(5s), and He-K(3d).Comment: 2 figure
Graduate Education in Agricultural Communication: The Need and Role
Is there a meed for graduate studies in agricultural communication
Prevalence of sexual harassment among Norwegian female elite athletes in relation to sport type
Although it is often assumed that the prevalence of sexual harassment is different in different sports, this assumption has not been empirically tested. This study considers whether the experience of sexual harassment varies by sport. The female elite athletes (N = 553) in the study participated in 56 different sport disciplines. These were grouped as follows :1) team or individual sports; 2) extent to which clothing required for competition is revealing ; 3) gender structure (male-or female dominated membership statistics); and 4) gender culture (masculine, gender-neutral, or feminine). The data show that sexual harassment occurs in every sport group. Female elite athletes who participated in âmasculineâ sports appear to experience more harassment than women in the other groups. We conclude that, when it comes to female athletesâ experiences of sexual harassment, sport type matters far less than sport participation per se
Mekong Basin Focal Project: Synthesis report
The Mekong Basin Focal Project aims were to assess water use, water productivity and
water poverty in the basin, and analyse the opportunities and risks of change in water
management that influences water poverty.
The main issue facing the Lower Mekong is not water availability (except for seasonally in
certain areas such as northeast Thailand) but the impact of changed flows (which may
result from dam or irrigation development or climate change) on ecology, fish production,
access to water and food security. Poverty is generally decreasing in the Mekong, but the
poorer people are not sharing in the improvements. Water governance and sharing of
benefits is a key challenge for the Mekong
\u3ci\u3eCaremark\u3c/i\u3e and ESG, Perfect Together: A Practical Approach to Implementing an Integrated, Efficient, and Effective \u3ci\u3eCaremark\u3c/i\u3e and EESG Strategy
With increased calls from investors, legislators, and academics for corporations to consider employee, environmental, social, and governance factors (âEESGâ) when making decisions, boards and managers are struggling to situate EESG within their existing reporting and organizational structures. Building on an emerging literature connecting EESG with corporate compliance, this Essay argues that EESG is best understood as an extension of the boardâs duty to implement and monitor a compliance program under Caremark. If a company decides to do more than the legal minimum, it will simultaneously satisfy legitimate demands for strong EESG programs and promote compliance with the law. Building on that insight, we explain how boards can marry existing corporate compliance programs with budding EESG programs. By integrating compliance and EESG, corporations can meet growing societal demands in an effective and efficient manner that capitalizes on existing structures. Lastly, we address how EESG and corporate compliance responsibilities should be allocated at the board and senior management level. Instead of separating compliance and EESG oversight, this Essay suggests that boards embrace a functional approach, delegating similar compliance and EESG oversight to the same committee and managers. By situating EESG within the boardâs existing fiduciary duties, this Essay provides academics, legislators, investors, and managers with a novel framework to conceptualize EESG while also offering a path forward for boards struggling to place the current EESG movement within their existing corporate structure
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