1,436 research outputs found
Sophomore Student Spirituality
The second year of college, with its unique challenges, has been found to present students with issues that could possibly make it more difficult than the first year. Some students experience the sophomore slump, which is defined in a myriad of ways, including reduced motivation and the uncertainty that comes with choosing a major. One major result of the slump is attrition between the sophomore and junior years. This study looks at the spiritual life of sophomores that experienced some aspect of the sophomore slump at a private, Christian liberal arts institution. It specifically looks at how they experienced the slump as well as their spiritual experiences during the sophomore year
Intermediate Wakimoto modules for Affine sl(n+1)
We construct certain boson type realizations of affine sl(n+1) that depend on
a parameter r. When r=0 we get a Fock space realization of Imaginary Verma
modules appearing in the work of the first author and when r=n they are the
Wakimoto modules described in the work of Feigin and Frenkel
Solution of the Roth-Marques-Durian Rotational Abrasion Model
We solve the rotational abrasion model of Roth, Marques and Durian
(arXiv:1009.3492), a one-dimensional quasilinear partial differential equation
resembling the inviscid Burgers equation with the unusual feature of a step
function factor as a coefficient. The complexity of the solution is primarily
in keeping track of the cases in the piecewise function that results from
certain amputation and interpolation processes, so we also extract from it a
model of an evolving planar tree graph that tracks the evolution of the coarse
features of the contour.Comment: 5 pages, 4 figure
Flexible and sustainable building components through kerf patterns
Populations in cities are increasing, the way we live is changing, and climate change is at the forefront of the architectural agenda. There is an urgent need to develop sustainable and flexible spaces for future urban housing. This paper examines the potential for using engineered timber, a renewable material that stores carbon, for the production of flexible housing. The paper focuses on kerfing, a cutting method that can turn flat rigid panels into foldable or curved elements. This project aims to develop light and flexible folded partitions that address the challenges of affordability and sustainability for our future cities
Measurement of the Target-Normal Single-Spin Asymmetry in Quasielastic Scattering from the Reaction ³He↑(e, e\u27)
We report the first measurement of the target single-spin asymmetry, Ay, in quasielastic scattering from the inclusive reaction ³He↑(e, e\u27) on a ³He gas target polarized normal to the lepton scattering plane. Assuming time-reversal invariance, this asymmetry is strictly zero for one-photon exchange. A nonzero Ay can arise from the interference between the one-and two-photon exchange processes which is sensitive to the details of the substructure of the nucleon. An experiment recently completed at Jefferson Lab yielded asymmetries with high statistical precision at Q2 = 0.13, 0.46, and 0.97 GeV2. These measurements demonstrate, for the first time, that the 3He asymmetry is clearly nonzero and negative at the 4σ-9σ level. Using measured proton-to-3He cross-section ratios and the effective polarization approximation, neutron asymmetries of -(1-3)% were obtained. The neutron asymmetry at high Q2 is related to moments of the generalized parton distributions (GPDs). Our measured neutron asymmetry at Q2 = 0.97 GeV2 agrees well with a prediction based on two-photon exchange using a GPD model and thus provides a new, independent constraint on these distributions
Topological modes bound to dislocations in mechanical metamaterials
Mechanical metamaterials are artificial structures with unusual properties,
such as negative Poisson ratio, bistability or tunable vibrational properties,
that originate in the geometry of their unit cell. At the heart of such unusual
behaviour is often a soft mode: a motion that does not significantly stretch or
compress the links between constituent elements. When activated by motors or
external fields, soft modes become the building blocks of robots and smart
materials. Here, we demonstrate the existence of topological soft modes that
can be positioned at desired locations in a metamaterial while being robust
against a wide range of structural deformations or changes in material
parameters. These protected modes, localized at dislocations, are the
mechanical analogue of topological states bound to defects in electronic
systems. We create physical realizations of the topological modes in prototypes
of kagome lattices built out of rigid triangular plates. We show mathematically
that they originate from the interplay between two Berry phases: the Burgers
vector of the dislocation and the topological polarization of the lattice. Our
work paves the way towards engineering topologically protected nano-mechanical
structures for molecular robotics or information storage and read-out.Comment: 13 pages, 6 figures; changes to text and figures and added analysis
on mode localization; see
http://www.lorentz.leidenuniv.nl/~paulose/dislocation-modes/ for accompanying
video
Scalable SCPPM Decoder
A decoder was developed that decodes a serial concatenated pulse position modulation (SCPPM) encoded information sequence. The decoder takes as input a sequence of four bit log-likelihood ratios (LLR) for each PPM slot in a codeword via a XAUI 10-Gb/s quad optical fiber interface. If the decoder is unavailable, it passes the LLRs on to the next decoder via a XAUI 10-Gb/s quad optical fiber interface. Otherwise, it decodes the sequence and outputs information bits through a 1-GB/s Ethernet UDP/IP (User Datagram Protocol/Internet Protocol) interface. The throughput for a single decoder unit is 150-Mb/s at an average of four decoding iterations; by connecting a number of decoder units in series, a decoding rate equal to that of the aggregate rate is achieved. The unit is controlled through a 1-GB/s Ethernet UDP/IP interface. This ground station decoder was developed to demonstrate a deep space optical communication link capability, and is unique in the scalable design to achieve real-time SCPP decoding at the aggregate data rate
Flux-Enabled Exploration of the Role of Sip1 in galactose yeast metabolism
13C metabolic flux analysis (13C MFA) is an important systems biology technique that has been used to investigate microbial metabolism for decades. The heterotrimer Snf1 kinase complex plays a key role in the preference Saccharomyces cerevisiae exhibits for glucose over galactose, a phenomenon known as glucose repression or carbon catabolite repression. The SIP1 gene, encoding a part of this complex, has received little attention, presumably, because its knockout lacks a growth phenotype. We present a fluxomic investigation of the relative effects of the presence of galactose in classically glucose-repressing media and/or knockout of SIP1 using a multi-scale variant of 13C MFA known as 2-Scale 13C metabolic flux analysis (2S-13C MFA). In this study, all strains have the galactose metabolism deactivated (gal1Δ background) so as to be able to separate the metabolic effects purely related to glucose repression from those arising from galactose metabolism. The resulting flux profiles reveal that the presence of galactose in classically glucose-repressing conditions, for a CEN.PK113-7D gal1Δ background, results in a substantial decrease in pentose phosphate pathway (PPP) flux and increased flow from cytosolic pyruvate and malate through the mitochondria toward cytosolic branched-chain amino acid biosynthesis. These fluxomic redistributions are accompanied by a higher maximum specific growth rate, both seemingly in violation of glucose repression. Deletion of SIP1 in the CEN.PK113-7D gal1Δ cells grown in mixed glucose/galactose medium results in a further increase. Knockout of this gene in cells grown in glucose-only medium results in no change in growth rate and a corresponding decrease in glucose and ethanol exchange fluxes and flux through pathways involved in aspartate/threonine biosynthesis. Glucose repression appears to be violated at a 1/10 ratio of galactose-to-glucose. Based on the scientific literature, we may have conducted our experiments near a critical sugar ratio that is known to allow galactose to enter the cell. Additionally, we report a number of fluxomic changes associated with these growth rate increases and unexpected flux profile redistributions resulting from deletion of SIP1 in glucose-only medium
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