1,104 research outputs found
A Study of the Role of the Superintendent of Schools in Teacher Negotiations in Class C and D School Districts in Nebraska
Collective bargaining by governmental employees and their employers is a reality in many divisions of state government. As of 1972, twenty-eight of the fifty states had enacted laws governing the process of collective bargaining between the state and its public employees. Seventeen of these twenty-eight states had separate and specific provisions in their laws for the process of collective bargaining between public school teachers and their boards of education
Validation of a smartphone app to map social networks of proximity
Social network analysis is a prominent approach to investigate interpersonal
relationships. Most studies use self-report data to quantify the connections
between participants and construct social networks. In recent years smartphones
have been used as an alternative to map networks by assessing the proximity
between participants based on Bluetooth and GPS data. While most studies have
handed out specially programmed smartphones to study participants, we developed
an application for iOS and Android to collect Bluetooth data from participants
own smartphones. In this study, we compared the networks estimated with the
smartphone app to those obtained from sociometric badges and self-report data.
Participants (n=21) installed the app on their phone and wore a sociometric
badge during office hours. Proximity data was collected for 4 weeks. A
contingency table revealed a significant association between proximity data
(rho = 0.17, p<0.0001), but the marginal odds were higher for the app (8.6%)
than for the badges (1.3%), indicating that dyads were more often detected by
the app. We then compared the networks that were estimated using the proximity
and self-report data. All three networks were significantly correlated,
although the correlation with self-reported data was lower for the app (rho =
0.25) than for badges (rho = 0.67). The scanning rates of the app varied
considerably between devices and was lower on iOS than on Android. The
association between the app and the badges increased when the network was
estimated between participants whose app recorded more regularly. These
findings suggest that the accuracy of proximity networks can be further
improved by reducing missing data and restricting the interpersonal distance at
which interactions are detected.Comment: 20 pages, 5 figure
Using Bluetooth Low Energy in smartphones to map social networks
Social networks have an important role in an individual's health, with the
propagation of health-related features through a network, and correlations
between network structures and symptomatology. Using Bluetooth-enabled
smartphones to measure social connectivity is an alternative to traditional
paper-based data collection; however studies employing this technology have
been restricted to limited sets of homogenous handsets. We investigated the
feasibility of using the Bluetooth Low Energy (BLE) protocol, present on users'
own smartphones, to measure social connectivity. A custom application was
designed for Android and iOS handsets. The app was configured to simultaneously
broadcast via BLE and perform periodic discovery scans for other nearby
devices. The app was installed on two Android handsets and two iOS handsets,
and each combination of devices was tested in the foreground, background and
locked states. Connectivity was successfully measured in all test cases, except
between two iOS devices when both were in a locked state with their screens
off. As smartphones are in a locked state for the majority of a day, this
severely limits the ability to measure social connectivity on users' own
smartphones. It is not currently feasible to use Bluetooth Low Energy to map
social networks, due to the inability of iOS devices to detect another iOS
device when both are in a locked state. While the technology was successfully
implemented on Android devices, this represents a smaller market share of
partially or fully compatible devices.Comment: 6 pages, 1 tabl
A descriptive bibliography of non-projected multi-sensory aids for teaching elementary arithmetic
Thesis (Ed.M.)--Boston Universit
Solutions of Extended Supersymmetric Matrix Models for Arbitrary Gauge Groups
Energy eigenstates for N=2 supersymmetric gauged quantum mechanics are found
for the gauges groups SU(n) and U(n). The analysis is aided by the existence of
an infinite number of conserved operators. The spectum is continuous.
Perturbative eigenstates for are also presented, a case which is relevant
for the conjectured description of M theory in the infinite momentum frame.Comment: 10 pages, LATEX, no figure
A Bayesian approach for inferring the dynamics of partially observed endemic infectious diseases from space-time-genetic data
We describe a statistical framework for reconstructing the sequence of transmission events between observed cases of an endemic infectious disease using genetic, temporal and spatial information. Previous approaches to reconstructing transmission trees have assumed all infections in the study area originated from a single introduction and that a large fraction of cases were observed. There are as yet no approaches appropriate for endemic situations in which a disease is already well established in a host population and in which there may be multiple origins of infection, or that can enumerate unobserved infections missing from the sample. Our proposed framework addresses these shortcomings, enabling reconstruction of partially observed transmission trees and estimating the number of cases missing from the sample. Analyses of simulated datasets show the method to be accurate in identifying direct transmissions, while introductions and transmissions via one or more unsampled intermediate cases could be identified at high to moderate levels of case detection. When applied to partial genome sequences of rabies virus sampled from an endemic region of South Africa, our method reveals several distinct transmission cycles with little contact between them, and direct transmission over long distances suggesting significant anthropogenic influence in the movement of infected dogs
Operator learning without the adjoint
There is a mystery at the heart of operator learning: how can one recover a
non-self-adjoint operator from data without probing the adjoint? Current
practical approaches suggest that one can accurately recover an operator while
only using data generated by the forward action of the operator without access
to the adjoint. However, naively, it seems essential to sample the action of
the adjoint. In this paper, we partially explain this mystery by proving that
without querying the adjoint, one can approximate a family of non-self-adjoint
infinite-dimensional compact operators via projection onto a Fourier basis. We
then apply the result to recovering Green's functions of elliptic partial
differential operators and derive an adjoint-free sample complexity bound.
While existing theory justifies low sample complexity in operator learning,
ours is the first adjoint-free analysis that attempts to close the gap between
theory and practice.Comment: 49 pages, 5 figure
Ultraviolet relaxation dynamics in uracil: Time-resolved photoion yield studies using a laser-based thermal desorption source
Wavelength-dependent measurements of the RNA base uracil, undertaken with nanosecond ultraviolet laser pulses, have previously identified a fragment at m/z = 84 (corresponding to the C3H4N2O+ ion) at excitation wavelengths ≤232 nm. This has been interpreted as a possible signature of a theoretically predicted ultrafast ring-opening occurring on a neutral excited state potential energy surface. To further investigate the dynamics of this mechanism, and also the non-adiabatic dynamics operating more generally in uracil, we have used a newly built ultra-high vacuum spectrometer incorporating a laser-based thermal desorption source to perform time-resolved ion-yield measurements at pump wavelengths of 267 nm, 220 nm, and 200 nm. We also report complementary data obtained for the related species 2-thiouracil following 267 nm excitation. Where direct comparisons can be made (267 nm), our findings are in good agreement with the previously reported measurements conducted on these systems using cold molecular beams, demonstrating that the role of initial internal energy on the excited state dynamics is negligible. Our 220 nm and 200 nm data also represent the first reported ultrafast study of uracil at pump wavelengths 3(1ππ*) state. These measurements do not, however, provide any evidence for the appearance of the m/z = 84 fragment within the first few hundred picoseconds following excitation. This key finding indicates that the detection of this specific species in previous nanosecond work is not directly related to an ultrafast ring-opening process. An alternative excited state process, operating on a more extended time scale, remains an open possibility
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