Improving Statistical Language Model Performance with Automatically Generated Word Hierarchies

An automatic word classification system has been designed which processes word unigram and bigram frequency statistics extracted from a corpus of natural language utterances. The system implements a binary top-down form of word clustering which employs an average class mutual information metric. Resulting classifications are hierarchical, allowing variable class granularity. Words are represented as structural tags --- unique $n$-bit numbers the most significant bit-patterns of which incorporate class information. Access to a structural tag immediately provides access to all classification levels for the corresponding word. The classification system has successfully revealed some of the structure of English, from the phonemic to the semantic level. The system has been compared --- directly and indirectly --- with other recent word classification systems. Class based interpolated language models have been constructed to exploit the extra information supplied by the classifications and some experiments have shown that the new models improve model performance.Comment: 17 Page Paper. Self-extracting PostScript Fil

Sampling methane in basalt on Earth and Mars

Peer reviewedPublisher PD

Evidence for Seismogenic Hydrogen Gas, a Potential Microbial Energy Source on Earth and Mars

M thanks the STFC for a PhD studentship and the NASA Astrobiology Institute for additional funding (NNAI13AA90A; Foundations of Complex Life, Evolution, Preservation and Detection on Earth and Beyond). Alison Wright, Roger Gibson and Edward Lynch are thanked for contributing samples. We thank three anonymous reviewers for their insightful comments.Peer reviewedPostprin

Establishing rates of binge drinking in the UK: anomalies in the data

YesAims: Several studies funded by the UK government have been influential in understanding `binge drinking¿ rates in the UK. This analysis aims to establish consistency between results and clarify UK rates of binge drinking. Method: The relevant sections of these surveys were compared: the Scottish Health Survey (SHS) 1998, the General Household Survey (GHS) 2002 and the Health Survey for England (HSE) 2003. In addition the methodology used by the Health Protection Agency in the Adult Drinking Patterns in Northern Ireland (2003) was compared to the approach used by the SHS, GHS and HSE. Results: Marked differences were observed between the results of the GHS 2002 and both the SHS 1998 and the HSE 2002 despite each using a similar methodology, with the HSE 2003 reporting a rate of binge drinking in young males of 57%, and the GHS a rate of 35%. These difference may be largely attributed to variations in the criteria in binge drinking in each study. These differences in interpretation do not appear to have been acknowledged. Indeed several key alcohol harm reduction documents made inaccurate citations of previous surveys. Conclusion: The media rhetoric on escalating rates of binge drinking in the UK should be regarded with caution until trends are based on standardized recording and reporting

Normative beliefs, misperceptions, and heavy episodic drinking in a British student sample.

YesObjective: Numerous studies have demonstrated the existence and effect of normative misperceptions on heavy episodic drinking behavior. However, there has been little work on these processes or application of normative-belief interventions outside the U.S. college system. The aim of the current study, therefore, was to investigate heavy episodic drinking and normative misperceptions in a U.K. university setting. Method: An email containing a link to a survey Web site was distributed to all current undergraduate students at the University of Paisley, Scotland. In addition to age and gender questions, the survey contained items on students¿ personal behavior and perception of the level of that behavior in three groups of increasing social distance: close friends, other students of the same age, and other people of the same age in U.K. society in general. Results: Completed surveys from 500 respondents were returned. In keeping with previous research, significant correlations were found between the respondents¿ behavior and the perception of that behavior in others, with beliefs about the most proximal individuals being the most strongly correlated. The majority of respondents were also found to overestimate alcohol consumption in other students. An age effect was noted, in which misperceptions appeared to decrease with age but did not vary between genders. Conclusions: The findings of the study indicate that the normative-belief alcohol consumption processes that have been found on U.S. college campuses also operate in U.K. university settings. This raises the possibility of applying social-norms interventions from the United States to the United Kingdom and potentially elsewhere in the world. Furthermore, the study noted apparent age effects in the degree of misperception, the implications of which are discusse

Diagnosing and dealing with the 'new British disease'.

Ye

A structural systematic study of three isomers of difluoro-N-(4-pyridyl)benzamide

The isomers 2,3-, (I), 2,4-, (II), and 2,5-difluoro-N-(4-pyridyl)benzamide, (III), all with formula C₁₂H₈F₂N₂O, all exhibit intramolecular C-H...O=C and N-H...F contacts [both with S(6) motifs]. In (I), intermolecular N-H...O=C interactions form one-dimensional chains along [010] [N...O = 3.0181 (16) Å], with weaker C-H...N interactions linking the chains into sheets parallel to the [001] plane, further linked into pairs via C-H...F contacts about inversion centres; a three-dimensional herring-bone network forms via C-H...π(py) (py is pyridyl) interactions. In (II), weak aromatic C-H...N(py) interactions form one-dimensional zigzag chains along [001]; no other interactions with H...N/O/F < 2.50 Å are present, apart from long N/C-H...O=C and C-H...F contacts. In (III), N-H...N(py) interactions form one-dimensional zigzag chains [as C(6) chains] along [010] augmented by a myriad of weak C-H...π(arene) and O=C...O=C interactions and C-H...O/N/F contacts. Compound (III) is isomorphous with the parent N-(4-pyridyl)benzamide [Noveron, Lah, Del Sesto, Arif, Miller & Stang (2002). J. Am. Chem. Soc. 124, 6613-6625] and the three 2/3/4-fluoro-N-(4-pyridyl)benzamides [Donnelly, Gallagher & Lough (2008). Acta Cryst. C64, o335-o340]. The study expands our series of fluoro(pyridyl)benzamides and augments our understanding of the competition between strong hydrogen-bond formation and weaker influences on crystal packing

A structural systematic study of four isomers of difluoro-N-(3-pyridyl)benzamide

The four isomers 2,4-, (I), 2,5-, (II), 3,4-, (III), and 3,5-difluoro-N-(3-pyridyl)benzamide, (IV), all with formula C12H8F2N2O, display molecular similarity, with interplanar angles between the C6/C5N rings ranging from 2.94 (11)° in (IV) to 4.48 (18)° in (I), although the amide group is twisted from either plane by 18.0 (2)-27.3 (3)°. Compounds (I) and (II) are isostructural but are not isomorphous. Intermolecular N-H...O=C interactions form one-dimensional C(4) chains along [010]. The only other significant interaction is C-H...F. The pyridyl (py) N atom does not participate in hydrogen bonding; the closest H...Npy contact is 2.71 Å in (I) and 2.69 Å in (II). Packing of pairs of one-dimensional chains in a herring-bone fashion occurs via [pi]-stacking interactions. Compounds (III) and (IV) are essentially isomorphous (their a and b unit-cell lengths differ by 9%, due mainly to 3,4-F2 and 3,5-F2 substitution patterns in the arene ring) and are quasi-isostructural. In (III), benzene rotational disorder is present, with the meta F atom occupying both 3- and 5-F positions with site occupancies of 0.809 (4) and 0.191 (4), respectively. The N-H...Npy intermolecular interactions dominate as C(5) chains in tandem with C-H...Npy interactions. C-H...O=C interactions form R22(8) rings about inversion centres, and there are [pi]-[pi] stacks about inversion centres, all combining to form a three-dimensional network. By contrast, (IV) has no strong hydrogen bonds; the N-H...Npy interaction is 0.3 Å longer than in (III). The carbonyl O atom participates only in weak interactions and is surrounded in a square-pyramidal contact geometry with two intramolecular and three intermolecular C-H...O=C interactions. Compounds (III) and (IV) are interesting examples of two isomers with similar unit-cell parameters and gross packing but which display quite different intermolecular interactions at the primary level due to subtle packing differences at the atom/group/ring level arising from differences in the peripheral ring-substitution patterns

VALIDATION OF A COMMERCIALLY AVAILABLE STRAIN GAUGE AGAINST A SERIES OF KNOWN LOADS USING A SHORT TIME APPROACH

The purpose of this study was to identify the content validity and accuracy of a commercially available strain gauge (GSTRENGTH (Exsurgo Technologies, Virginia, USA), aimed at use within athletic populations. Six standardised IWF (International Weightlifting Federation) calibrated weights (5-, 25-, 50-, 100-, 200-, 250-kg) were hung from the strain gauge and raw data was collected over a five-second period and exported to a computer. A perfect relationship between the known loads and the strain gauge (r = 1.00, p\u3c0.001) was identified, although the strain gauge was found to have a small overestimation error with no fixed or proportional bias. During data collection there were non-significant, trivial-small differences between the first and last second, demonstrating minimal drift. The commercially available strain gauge was found to be valid when compared to the known loads. Further investigation of the strain gauge is required to assess the concurrent validity when compared to gold standard methods of assessment, such as force plates, in a range of test designs