Alex Craven

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Ghent University

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University of Michigan

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Papers by Alex Craven

What Influences Principals' Perceptions of Academic Climate? A Nationally Representative Study of the Direct Effects of Perception on Climate

Leadership and Policy in Schools, 2011

Using a nationally representative sample of public high schools (N = 439), we examined the extent... more Using a nationally representative sample of public high schools (N = 439), we examined the extent to which the principal's perception of their influence over instruction, the evaluation of nonacademic related tasks as well as academic related tasks, and their relationship with the school district relates to their perception of academic climate while controlling for school-level covariates. Little attention has been given to date to the principal's perception of their responsibilities and how it relates to their view of academic climate. The findings link academic climate with direct effects from principal perceptions of support and evaluation from the district.

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Encoding in the Visual Word Form Area: An fMRI Adaptation Study of Words versus Handwriting

Journal of Cognitive Neuroscience, 2010

■ Written texts are not just words but complex multidimensional stimuli, including aspects such a... more ■ Written texts are not just words but complex multidimensional stimuli, including aspects such as case, font, and handwriting style, for example. Neuropsychological reports suggest that left fusiform lesions can impair the reading of text for word (lexical) content, being associated with alexia, whereas rightsided lesions may impair handwriting recognition. We used fMRI adaptation in 13 healthy participants to determine if repetitionsuppression occurred for words but not handwriting in the left visual word form area ( VWFA) and the reverse in the right fusi-form gyrus. Contrary to these expectations, we found adaptation for handwriting but not for words in both the left VWFA and the right VWFA homologue. A trend to adaptation for words but not handwriting was seen only in the left middle temporal gyrus. An analysis of anterior and posterior subdivisions of the left VWFA also failed to show any adaptation for words. We conclude that the right and the left fusiform gyri show similar patterns of adaptation for handwriting, consistent with a predominantly perceptual contribution to text processing. ■ the ability to recognize that "DRAG" is the same word as "drag" is a significant perceptual accomplishment, given the striking structural dissimilarities between the upper and the lower case versions of each letter, and "drag" and "drag " need to be perceived as the same word if they are to be read correctly. Such invariant representations are required visual inputs in connectionist models of the reading process .

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The Map of the Witt Ring of a Domain into the Witt Ring of its Field of Fractions

Proceedings of The American Mathematical Society, 1975

Extracting comprehensible rules from neural networks via genetic algorithms

A common problem in KDD (Knowledge Discovery in Databases) is the presence of noise in the data b... more A common problem in KDD (Knowledge Discovery in Databases) is the presence of noise in the data being mined. Neural networks are robust and have a good tolerance to noise, which makes them suitable for mining very noisy data. However, they have the well-known disadvantage of not discovering any high-level rule that can be used as a support for human decision making. In this work we present a method for extracting accurate, comprehensible rules from neural networks. The proposed method uses a genetic algorithm to find a good neural network topology. This topology is then passed to a rule extraction algorithm, and the quality of the extracted rules is then fed back to the genetic algorithm. The proposed system is evaluated on three public-domain data sets and the results show that the approach is valid

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Atomic and Molecular Processes in the Solar System and Planetary Atmospheres:. AN Overview and Some Examples

This chapter provides a brief summary of the overall role of atomic and molecular (ATM) processes... more This chapter provides a brief summary of the overall role of atomic and molecular (ATM) processes in solar system environments and a few examples of Alex Dalgarno's contributions. The bulk of the chapter is devoted to the role of ion-neutral collisional processes at comet Halley and at Saturn's satellites Enceladus and Titan.

A Sandbox for Exploring the OpenFire Processor

Responses of the Jovian Atmosphere to Cometary Particles and Photon Impacts

Detailed calculations were performed of the deposition of energetic oxygen ions into the atmosphe... more Detailed calculations were performed of the deposition of energetic oxygen ions into the atmosphere of Jupiter. A Monte Carlo simulation was used. Similar processes occur in other astrophysical environments to which our methods can be applied. In particular Cravens has suggested that the X-ray emissions seen from comets are due to transitions from excited states following capture of electrons by solar wind ions colliding with the atmosphere of the comet. Alternative proposals have been advanced for the source of the cometary X-rays. We have carried out a study of the spectra and have shown that with the spectral resolution of about 20 eV the different excitation mechanisms can be distinguished. The response of the two components of the solar wind predict a spectrum that is consistent with the cometary observations. X-rays from the comets arise from the slow solar wind.

A laser Doppler system for the remote sensing of boundary layer winds in clear air conditions

The system discussed uses a laser Doppler radar in combination with a velocity azimuth display mo... more The system discussed uses a laser Doppler radar in combination with a velocity azimuth display mode of scanning to determine the three-dimensional wind field in the atmospheric boundary layer. An attractive feature of this CW monostatic system is that the ambient aerosol provides a 'sufficient' scattering target to permit operation under clear air conditions. Spatial resolution is achieved by focusing.

Linear phenol-formaldehyde polymers—condensation of p-chlorophenol with formaldehyde

Journal of Polymer Science, 1956

High molecular linear polymers were prepared by the condensation of p-chlorophenol with formaldeh... more High molecular linear polymers were prepared by the condensation of p-chlorophenol with formaldehyde at 150°C. for 24 hours in a closed system with bis(2-ethoxyethyl) ether as solvent and p-toluenesulfonic acid as catalyst. The importance of reaction variables including temperature, time, solvent, catalyst, and concentration and ratio of reactants was studied. Polymers of this type were also prepared by the polymerization of 4-chloro-2-hydroxymethylphenol and by the condensation of p-chlorophenol with 2,6-bis(hydroxymethyl)-4-chlorophenol. Data obtained on the polymers from the three independent routes indicated the presence of methylene bridges between the ortho position of the p-chlorophenol residues. The polymers were soluble in N,N-dimethyl formamide and reacted readily with acetic anhydride to form the corresponding acetylated derivatives.

YBCO coated conductors by an MOD/RABiTS™ process

IEEE Transactions on Applied Superconductivity, 2003

Abstract Commercialization of YBa 2 Cu 3 O 7-x (YBCO) superconducting coated conductor composite ... more

Airglow from the inner comas of comets

Icarus, 1978

The intensities of radiation from the inner comas of comets which are composed primarily of water... more The intensities of radiation from the inner comas of comets which are composed primarily of water and carbon monoxide have been calculated. Only 'airglow' emissions initiated by the absorption of EUV radiation have been considered. The photoionizations of H2O, CO, CO2, and N2 are the most important emission sources, although photoelectron excitation is also considered. Among the emission features for which intensities were calculated are H2O(+), CO(+) (first negative), CO (fourth positive), CO (Cameron), CO2(+), N2 (Vegard-Kaplan), N2(+) (first negative), and O I (1304 A). In the inner coma (collision region) these airglow mechanisms are shown to be possible competitors with the usually assumed resonance-scattering and fluorescence-excitation mechanisms appropriate for the outer coma and tail.

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Complete genome sequence of Caulobacter crescentus

Proceedings of The National Academy of Sciences, 2001

The complete genome sequence of Caulobacter crescentus was determined to be 4,016,942 base pairs ... more The complete genome sequence of Caulobacter crescentus was determined to be 4,016,942 base pairs in a single circular chromosome encoding 3,767 genes. This organism, which grows in a dilute aquatic environment, coordinates the cell division cycle and multiple cell differentiation events. With the annotated genome sequence, a full description of the genetic network that controls bacterial differentiation, cell growth, and cell cycle progression is within reach. Twocomponent signal transduction proteins are known to play a significant role in cell cycle progression. Genome analysis revealed that the C. crescentus genome encodes a significantly higher number of these signaling proteins (105) than any bacterial genome sequenced thus far. Another regulatory mechanism involved in cell cycle progression is DNA methylation. The occurrence of the recognition sequence for an essential DNA methylating enzyme that is required for cell cycle regulation is severely limited and shows a bias to intergenic regions. The genome contains multiple clusters of genes encoding proteins essential for survival in a nutrient poor habitat. Included are those involved in chemotaxis, outer membrane channel function, degradation of aromatic ring compounds, and the breakdown of plantderived carbon sources, in addition to many extracytoplasmic function sigma factors, providing the organism with the ability to respond to a wide range of environmental fluctuations. C. crescentus is, to our knowledge, the first free-living ␣-class proteobacterium to be sequenced and will serve as a foundation for exploring the biology of this group of bacteria, which includes the obligate endosymbiont and human pathogen Rickettsia prowazekii, the plant pathogen Agrobacterium tumefaciens, and the bovine and human pathogen Brucella abortus.

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Linear phenol-formaldehyde polymers—condensation of p-chlorophenol with formaldehyde

Journal of Polymer Science, 1956

The first completely sj nthetic polymers to be utilized commercially were obtained from phenol an... more

A comparison of parsing technologies for the biomedical domain

This paper reports on a number of experiments which are designed to investigate the extent to whi... more This paper reports on a number of experiments which are designed to investigate the extent to which current nlp resources are able to syntactically and semantically analyse biomedical text. We address two tasks: (a) parsing a real corpus with a hand-built wide-coverage grammar, producing both syntactic analyses and logical forms and (b) automatically computing the interpretation of compound nouns where the head is a nominalisation (e.g. hospital arrival means an arrival at hospital, while patient arrival means an arrival of a patient). For the former task we demonstrate that flexible and yet constrained pre-processing techniques are crucial to success: these enable us to use part-of-speech tags to overcome inadequate lexical coverage, and to package up complex technical expressions prior to parsing so that they are blocked from creating misleading amounts of syntactic complexity. We argue that the xml-processing paradigm is ideally suited for automatically preparing the corpus for parsing. For the latter task, we compute interpretations of the compounds by exploiting surface cues and meaning paraphrases, which in turn are extracted from the parsed corpus. This provides an empirical setting in which we can compare the utility of a comparatively deep parser vs. a shallow one, exploring the trade-off between resolving attachment ambiguities on the one hand and generating errors in the parses on the other. We demonstrate that a model of the meaning of compound nominalisations is achievable with the aid of current broad-coverage parsers.

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A change in humidification system can eliminate endotracheal tube occlusion

Journal of Critical Care

Inadequate airway humidification can result in endotracheal tube occlusion. There is evidence tha... more Inadequate airway humidification can result in endotracheal tube occlusion. There is evidence that heat and moisture exchangers (HMEs) are more prone to endotracheal tube occlusion than heated humidifiers (HHs) that contain a heated wire circuit. We aimed to compare the incidence of endotracheal tube occlusion while introducing a new dual-heated wire circuit HH in place of an established hydrophobic HME. This was a prospective observational study. All patients who required intubation were included in our analysis. Univariate statistical analysis was performed using a Fisher exact test. P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; .05 was considered statistically significant. There were 158 patients in the HME group and 88 patients in the HH group. The incidence of endotracheal tube occlusion was 5.7% in the HME group and 0% in the HH group. Statistical analysis revealed a significant difference between the 2 groups (P = .02). In light of this finding, we changed our practice to provide humidification exclusively by HH. In the subsequent 18-month period, there were no further episodes of endotracheal tube occlusion. Our study demonstrates that there is a significant increase in the incidence of endotracheal tube occlusion when using a hydrophobic HME compared with an HH and that using a dual-heated wire circuit HH can eliminate endotracheal tube occlusion.

High-spin [(pif72)2(nuf72)-1] configuration, two-particle-one-hole states in 49Ti

Physical Review C, 1984

The 51V(d--&amp;gt;,alpha)49Ti reaction has been studied with 79.4-MeV vector polarized deute... more The 51V(d--&amp;gt;,alpha)49Ti reaction has been studied with 79.4-MeV vector polarized deuterons. Angular distributions of the differential cross section and vector analyzing power have been measured for strongly-populated states up to an excitation energy of 5 MeV. Two-particle-one-hole states of the [(pif72)2(nuf72)-1] configuration were identified from the characteristic L=6 shapes of the differential cross section and J=7 patterns of the vector

Linear phenol-formaldehyde polymers---condensation of p-chlorophenol with formaldehyde

The first completely sj nthetic polymers to be utilized commercially were obtained from phenol an... more

A Laser Velocimeter for Remote Wind Sensing

... 20 TA Lehman, TA Elwood, JT Bursey, and JL Beauchamp, J. Amer. Chem. Soc. 93, 2108 (1971). 21... more

Ministers of State: The Established Church in Lancashire during the English Revolution, 1642–1660

Northern History, 2008

ALTHOUGH THE IMPORTANCE of religion in causing and driving the Civil War has rarely been doubted,... more ALTHOUGH THE IMPORTANCE of religion in causing and driving the Civil War has rarely been doubted, historians' attention has more often been drawn to the study of 'Puritanism' before the outbreak of the wars, and 'radicalism' during them. The focus has been on the issues of ...

For the better uniting of this nationâ: the 1649 Oath of Engagement and the people of Lancashire: The 1649 Oath of Engagement and the people of Lancashire

Historical Research, 2010

On 2 January 1650, the Act for subscribing the Engagement was passed. By this, the English republ... more On 2 January 1650, the Act for subscribing the Engagement was passed. By this, the English republic's oath of loyalty was extended to ‘all men whatsoever within the Commonwealth of England, of the age of eighteen years and upwards’. Although the controversy surrounding the Engagement has been much studied, the administration of the oath has drawn little attention. This is not surprising given that very few returns survived the 1661 order for their destruction. Yet, among these scanty records, there survive two separate sets of returns for Lancashire: the first was collected between June 1650 and April 1651 at Blackburn, Bury, Heywood, Middleton, Preston and Wigan; the second was compiled at Manchester between February and December 1651, and has been previously unnoticed by historians. These two documents provide valuable evidence of the government apparatus by which the oath was administered, and of the kind of people who took it. The returns enhance our understanding of the motivation for taking the Engagement, and measure commitment to the new regime.

What Influences Principals' Perceptions of Academic Climate? A Nationally Representative Study of the Direct Effects of Perception on Climate

Leadership and Policy in Schools, 2011

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Encoding in the Visual Word Form Area: An fMRI Adaptation Study of Words versus Handwriting

Journal of Cognitive Neuroscience, 2010

Download

The Map of the Witt Ring of a Domain into the Witt Ring of its Field of Fractions

Proceedings of The American Mathematical Society, 1975

Extracting comprehensible rules from neural networks via genetic algorithms

Download

Atomic and Molecular Processes in the Solar System and Planetary Atmospheres:. AN Overview and Some Examples

A Sandbox for Exploring the OpenFire Processor

Responses of the Jovian Atmosphere to Cometary Particles and Photon Impacts

A laser Doppler system for the remote sensing of boundary layer winds in clear air conditions

Linear phenol-formaldehyde polymers—condensation of p-chlorophenol with formaldehyde

Journal of Polymer Science, 1956

YBCO coated conductors by an MOD/RABiTS™ process

IEEE Transactions on Applied Superconductivity, 2003

Abstract Commercialization of YBa 2 Cu 3 O 7-x (YBCO) superconducting coated conductor composite ... more

Airglow from the inner comas of comets

Icarus, 1978

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Complete genome sequence of Caulobacter crescentus

Proceedings of The National Academy of Sciences, 2001

Download

Linear phenol-formaldehyde polymers—condensation of p-chlorophenol with formaldehyde

Journal of Polymer Science, 1956

The first completely sj nthetic polymers to be utilized commercially were obtained from phenol an... more

A comparison of parsing technologies for the biomedical domain

Download

A change in humidification system can eliminate endotracheal tube occlusion

Journal of Critical Care

High-spin [(pif72)2(nuf72)-1] configuration, two-particle-one-hole states in 49Ti

Physical Review C, 1984

Linear phenol-formaldehyde polymers---condensation of p-chlorophenol with formaldehyde

The first completely sj nthetic polymers to be utilized commercially were obtained from phenol an... more

A Laser Velocimeter for Remote Wind Sensing

... 20 TA Lehman, TA Elwood, JT Bursey, and JL Beauchamp, J. Amer. Chem. Soc. 93, 2108 (1971). 21... more

Ministers of State: The Established Church in Lancashire during the English Revolution, 1642–1660

Northern History, 2008

For the better uniting of this nationâ: the 1649 Oath of Engagement and the people of Lancashire: The 1649 Oath of Engagement and the people of Lancashire

Historical Research, 2010

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