1,484 research outputs found
A classical reactive potential for molecular clusters of sulphuric acid and water
We present a two-state empirical valence bond (EVB) potential describing
interactions between sulphuric acid and water molecules and designed to model
proton transfer between them within a classical dynamical framework. The
potential has been developed in order to study the properties of molecular
clusters of these species, which are thought to be relevant to atmospheric
aerosol nucleation. The particle swarm optimisation method has been used to fit
the parameters of the EVB model to density functional theory (DFT)
calculations. Features of the parametrised model and DFT data are compared and
found to be in satisfactory agreement. In particular, it is found that a single
sulphuric acid molecule will donate a proton when clustered with four water
molecules at 300 K and that this threshold is temperature dependent
An evaluation of the signature extension approach to large area crop inventories utilizing space image data
The author has identified the following significant results. Two examples of haze correction algorithms were tested: CROP-A and XSTAR. The CROP-A was tested in a unitemporal mode on data collected in 1973-74 over ten sample segments in Kansas. Because of the uniformly low level of haze present in these segments, no conclusion could be reached about CROP-A's ability to compensate for haze. It was noted, however, that in some cases CROP-A made serious errors which actually degraded classification performance. The haze correction algorithm XSTAR was tested in a multitemporal mode on 1975-76 LACIE sample segment data over 23 blind sites in Kansas and 18 sample segments in North Dakota, providing wide range of haze levels and other conditions for algorithm evaluation. It was found that this algorithm substantially improved signature extension classification accuracy when a sum-of-likelihoods classifier was used with an alien rejection threshold
Forming Disk Galaxies in Lambda CDM Simulations
We used fully cosmological, high resolution N-body + SPH simulations to
follow the formation of disk galaxies with rotational velocities between 135
and 270 km/sec in a Lambda CDM universe. The simulations include gas cooling,
star formation, the effects of a uniform UV background and a physically
motivated description of feedback from supernovae. The host dark matter halos
have a spin and last major merger redshift typical of galaxy sized halos as
measured in recent large scale N--Body simulations. The simulated galaxies form
rotationally supported disks with realistic exponential scale lengths and fall
on both the I-band and baryonic Tully Fisher relations. An extended stellar
disk forms inside the Milky Way sized halo immediately after the last major
merger. The combination of UV background and SN feedback drastically reduces
the number of visible satellites orbiting inside a Milky Way sized halo,
bringing it in fair agreement with observations. Our simulations predict that
the average age of a primary galaxy's stellar population decreases with mass,
because feedback delays star formation in less massive galaxies. Galaxies have
stellar masses and current star formation rates as a function of total mass
that are in good agreement with observational data. We discuss how both high
mass and force resolution and a realistic description of star formation and
feedback are important ingredients to match the observed properties of
galaxies.Comment: Revised version after the referee's comments. Conclusions unchanged.
2 new plots. MNRAS in press. 20 plots. 21 page
Internal Marketing Perceptions in Intercollegiate Athletics and Their Influence on Organizational Commitment
While scholars have previously focused on the external impact of marketing efforts in college athletics (e.g., Gladden, Irwin, & Sutton, 2001), little research has been done on the internal marketing orientation of collegiate sport properties and its respective impact on college sport. The purpose of this study is to determine the perceptions of internal marketing in college athletics and to examine if those perceptions have an effect on the level of organizational commitment among departmental employees. Survey methodology collected information from 248 athletic department administrators at NCAA FBS and FCS institutions. Results indicate that internal marketing orientation strongly influenced affective commitment to the organization. Further, internal marketing was found to fully mediate the relationship of job function and affective commitment. Finally, theorized moderators of job type, level of competition and gender were not statistically significant. The results support the assertion that an internal marketing orientation can be effectively implemented to foster the development of affective commitment to the organization
Breathing in Low Mass Galaxies: A Study of Episodic Star Formation
We simulate the collapse of isolated dwarf galaxies using SPH + N-Body
simulations including a physically motivated description of the effects of
supernova feedback. As the gas collapses and stars form, the supernova feedback
disrupts enough gas to temporarily quench star formation. The gas flows outward
into a hot halo, where it cools until star formation can continue once more and
the cycle repeats. The star formation histories of isolated Local Group dwarf
galaxies exhibit similar episodic bursts of star formation. We examine the mass
dependence of the stellar velocity dispersions and find that they are no less
than half the velocity of the halos measured at the virial radius.Comment: 5 pages, 3 figures, accepted ApJ. Full resolution figures and movies
available at http://hpcc.astro.washington.edu/feedbac
Intercollegiate Athletics and Institutional Fundraising: A Meta-Analysis
After nearly 30 years of research, the disparate findings of studies examining the influence of intercollegiate athletics on private, individual giving to higher education institutions have failed to generate generalizable knowledge. The current study examined all available empirical studies conducted between 1976 and 2008 on this topic. Meta-analysis results indicate that intercollegiate athletics does have a small, but statistically significant, effect on giving. Follow-up analysis revealed four significant moderators on the strength of the intercollegiate athletic-private giving relationship: the gift target (i.e., athletic vs. academic programs), the alumni status of the donor, the level of NCAA membership, and whether or not the institution competes in football. Implications of the results and directions for future research are discussed
Being on the Juvenile Dermatomyositis Rollercoaster: a qualitative study
Objectives: Juvenile Dermatomyositis is a rare, potentially life-threatening condition with no known cure. There is no published literature capturinghow children and young people feel about their condition, from their perspective. This study was therefore unique in that it asked children and young people what is it like to live with Juvenile Dermatomyositis.
Methods: Data wereobtained from fifteen young people with Juvenile Dermatomyositis, between eightand nineteen years of age from one Paediatric Rheumatology department using audio-recordedinterpretive phenomenology interviews. Data were analyzed phenomenologically, using a process that derives narratives from transcripts resulting in a collective composite of participants shared experiences, called a‘phenomenon’.
Results:The overarching metaphor of a rollercoaster captures the phenomenon of living withJuvenile Dermatomyositisas a young person, with the ups and downs at different time points clearly described by those interviewed. The five themes plotted on the rollercoaster, began with confusion; followed by feeling different, being sick, steroidal and scared from the medications; uncertainty; and then ended with acceptance of the disease over time.
Conclusion: Young people were able to talk about their experiences about having Juvenile Dermatomyositis. Our findings will aid clinicians in their practice by gaining a deeper understanding of what daily life is like and highlighting ways to enhance psychosocial functioning. Hopefully, this study and any further resulting studies,will raise understanding of Juvenile Dermatomyositis worldwide and will encourage health care professionals to better assess psychosocial needs in the future
Orthogonal Arrays of Strength Three from Regular 3-Wise Balanced Designs
The construction given in Kreher, J Combin Des 4 (1996) 67 is extended to obtain new infinite families of orthogonal arrays of strength 3. Regular 3-wise balanced designs play a central role in this construction
Secure exchange of information by synchronization of neural networks
A connection between the theory of neural networks and cryptography is
presented. A new phenomenon, namely synchronization of neural networks is
leading to a new method of exchange of secret messages. Numerical simulations
show that two artificial networks being trained by Hebbian learning rule on
their mutual outputs develop an antiparallel state of their synaptic weights.
The synchronized weights are used to construct an ephemeral key exchange
protocol for a secure transmission of secret data. It is shown that an opponent
who knows the protocol and all details of any transmission of the data has no
chance to decrypt the secret message, since tracking the weights is a hard
problem compared to synchronization. The complexity of the generation of the
secure channel is linear with the size of the network.Comment: 11 pages, 5 figure
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