Gender variation in writing : analyzing online dating ads

This dissertation presents a study of gendered language variation and linguistic indexicality in computer-mediated communication. A two-pronged approach combining the analysis of language production in a corpus of 103,000 English-language online dating ads with a language perception study (891 participants) is taken towards identifying the usage patterns and social meanings of nine features of e-grammar (Herring 2012). The indexicalities of features exhibiting gendered patterns in production as well as perception, emoticons (e.g. : ) ) and prosodic items (e.g. haha), are discussed in light of their linguistic and social context. Drawing on empirical research on American gender ideologies, the study argues that they index characteristics such as friendliness and emotional expressiveness, both stereotypically associated with women. In an instance of indirect indexicality (Ochs 1992), they are then linked to femininity in this type of computer-mediated communication. In production, the same features exhibit a strong audience effect (Bell 1984): women, for instance, use them more frequently in ads directed at other women. Throughout the analysis, the study makes use of and illustrates use cases for computational tools such as machine learning algorithms or automatic part-of-speech tagging in sociolinguistic research. At the same time, it attempts to strike a balance between a quantitative, data-driven approach and the nuanced analysis of gender identities and linguistic indexicality in the performance of gendered identitiesEnglis

Doube-pulse Laser-induced Breakdown Spectroscopy of Multi-element Sample Containing Low- And High-Z Analytes

Laser-induced breakdown spectroscopy (LIBS) is a portable, remote, non-invasive analytical technique which effectively distinguishes neutral and ionic species for a range of low- to high-Z elements in a multi-element target. Subsequently, LIBS holds potential in special nuclear material (SNM) sensing and nuclear forensics requiring minimal sample preparation and detecting isotopic shifts which allows for differentiation in SNM (namely U) enrichment levels. Feasible applications include not only nonproliferation and homeland security but also nuclear fuel prospecting and industrial safeguard endorsement. Elements of higher mass with complex atomic structures, such as U, however, result in crowded emission spectra with LIBS, and characteristic emission lines are challenging to discern. Preliminary research suggests double-pulse LIBS (DPLIBS) improves signal sensitivity for analytes of lower atomic mass over conventional single-pulse LIBS (SPLIBS). This study investigates signal sensitivity for low- and high-Z analytes in a glass matrix containing U (1.3%) comparing DPLIBS to SPLIBS. DPLIBS involves sequential firing of 1064 Nd: YAG (FWHM 9 ns) pre-pulse and 10.6 µm TEA CO2 (FWHM 50-100 ns) heating pulse in near collinear geometry; SPLIBS entails only the Nd:YAG laser. Optimization of experimental parameters including inter-pulse delay and energy follows identification of characteristic lines for bulk analytes Ca, Na, and Si and trace analyte U for both DPLIBS and SPLIBS. Temporally-integrated excitation temperature and electron density as well as neutral-to-ionic species ratio constitute relative figures of merit for both DPLIBS and SPLIBS plasma characterization. Temporally-resolved studies provide insight into high-Z U analyte persistence and signal enhancement with DPLIBS as compared to low-Z bulk analytes. The study predicts and discusses optimal emission conditions of U lines and relative figures of merit in both SPLIBS and DPLIBS

The Hob system for verifying software design properties

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2007.Includes bibliographical references (p. 157-164).This dissertation introduces novel techniques for verifying that programs conform to their designs. My Hob system, as described in this dissertation, allows developers to statically ensure that implementations preserve certain specified properties. Hob verifies heap-based properties that can express important aspects of a program's design. The key insight behind my approach is that Hob can establish detailed software design properties--properties that lie beyond the reach of extant static analysis techniques due to scalability or precision issues-by focusing the verification task. In particular, the Hob approach applies scalable static analysis techniques to the majority of the modules of a program and very precise, unscalable, static analysis or automated theorem proving techniques to certain specific modules of that program: those that require the precision that such analyses can deliver. The use of assume/guarantee reasoning allows the analysis engine to harness the strengths of both scalable and precise static analysis techniques to analyze large programs (which would otherwise require scalable, imprecise analyses) with sufficient precision to establish detailed data structure consistency properties, e.g. heap shape properties.(cont.) A set-based specification language enables the different analysis techniques to cooperate in verifying the specified design properties. My preliminary results show that it is possible to successfully verify detailed design-level properties of benchmark applications: I have used the Hob system to verify user-relevant properties of a water molecule simulator, a web server, and a minesweeper game. These properties constrain the behaviour of the program by stating that selected sets of objects are always equal or disjoint throughout the program's execution.by Patrick Lam.Ph.D

Correlated exciton dynamics in semiconductor nanostructures

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2013.Cataloged from PDF version of thesis.Includes bibliographical references (p. 211-223).The absorption and dissipation of energy in semiconductor nanostructures are often determined by excited electron dynamics. In semiconductors, one fundamentally important electronic state is an exciton, an excited electron bound to a positively charged vacancy. Excitons can become correlated with other excitons, mutually influencing one another and exhibiting collective properties. The focus of this dissertation concerns the origins, effects, and control of correlated excitons in semiconductor nanostructures. Correlated Coulomb interactions can occur between excitons, resulting in energy shifts and dephasing in each exciton. Two-dimensional Fourier-transform optical spectroscopy is a powerful tool to understand Coulomb correlations; the technique relates exciton dynamics during distinct time periods. However, the technique is still limited by weak spectral features. Using two-dimensional pulse shaping methods, waveforms of excitation fields were tailored to selectively amplify spectral features of correlated exciton states in gallium arsenide quantum wells. With the aid of theoretical models, 2D spectra of quantum wells revealed clear contributions of Coulomb correlations to the exciton dynamics. Time and power dependent properties of the 2D spectra indicate several mechanisms for exciton interactions that are neglected in commonly used theoretical models. If a semiconductor material is fabricated within a microcavity, optical fields can be trapped around the semiconductor, strongly distorting properties of the semiconductor excitons and forming new quasi-particles called exciton-polaritons. Theoretical work has suggested exciton-polariton Coulomb correlation strengths can be reduced compared to that of excitons. Using two-dimensional Fourier-transform optical spectroscopy, control of Coulomb correlations was demonstrated by varying the cavity structure. The cavity fields were also shown to induce high-order correlated interactions among exciton-polaritons. A macroscopic quantum degenerate system of exciton-polaritons can also become correlated, exhibiting long-range order typical of a Bose-Einstein condensate. However, unlike a Bose-Einstein condensate, exciton-polartions are not typically in thermal equilibrium. Using a sample with exciton-polariton lifetimes longer than previous samples, the macroscopic behavior of exciton-polaritons was investigated by imaging the exciton-polariton photoluminescence. Condensation depended significantly on spatially-varying potential energy surfaces. Using optically-induced harmonic potential barriers, thermal equilibrium among exciton-polaritons was achieved, with exciton-polaritons forming a Bose-Einstein distribution at densities above and below the condensation phase transition.by Patrick Wen.Ph.D

Conception d'un systeme de bases de donnees relationnel multiprocesseur

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Rare isotope production in statistical multifragmentation

Producing rare isotopes through statistical multifragmentation is investigated using the Mekjian method for exact solutions of the canonical ensemble. Both the initial fragmentation and the the sequential decay are modeled in such a way as to avoid Monte Carlo and thus provide yields for arbitrarily scarce fragments. The importance of sequential decay, exact particle-number conservation and the sensitivities to parameters such as density and temperature are explored. Recent measurements of isotope ratios from the fragmentation of different Sn isotopes are interpreted within this picture.Comment: 10 eps figure

Smallest detectable change in volume differs between mass flow sensor and pneumotachograph

<p>Abstract</p> <p>Background</p> <p>To assess a pulmonary function change over time the mass flow sensor and the pneumotachograph are widely used in commercially available instruments. However, the smallest detectable change for both devices has never been compared. Therefore, the aim of this study is to determine the smallest detectable change in vital capacity (VC) and single-breath diffusion parameters measured by mass flow sensor and or pneumotachograph.</p> <p>Method</p> <p>In 28 healthy pulmonary function technicians VC, transfer factor for carbon monoxide (DLCO) and alveolar volume (VA) was repeatedly (10×) measured. The smallest detectable change was calculated by 1.96 x Standard Error of Measurement ×√2.</p> <p>Findings</p> <p>The mean (range) of the smallest detectable change measured by mass flow sensor and pneumotachograph respectively, were for VC (in Liter): 0.53 (0.46-0.65); 0.25 (0.17-0.36) (<it>p </it>= 0.04), DLCO (in mmol*kPa^-1*min^-1): 1.53 (1.26-1.7); 1.18 (0.84-1.39) (<it>p </it>= 0.07), VA (in Liter): 0.66. (0.53-0.82); 0.43 (0.34-0.53) (<it>p </it>= 0.04) and DLCO/VA (in mmol*kPa^-1*min^-1*L^-1): 0.22 (0.19-0.28); 0.19 (0.14-0.22) (<it>p </it>= 0.79).</p> <p>Conclusions</p> <p>Smallest detectable significant change in VC and VA as measured by pneumotachograph are smaller than by mass flow sensor. Therefore, the pneumotachograph is the preferred instrument to estimate lung volume change over time in individual patients.</p

Experimental investigation of the variability of concrete durability properties

One of the main objectives of the APPLET project was to quantify the variability of concrete properties to allow for a probabilistic performance-based approach regarding the service lifetime prediction of concrete structures. The characterization of concrete variability was the subject of an experimental program which included a significant number of tests allowing the characterization of durability indicators or performance tests. Two construction sites were selected from which concrete specimens were periodically taken and tested by the different project partners. The obtained results (mechanical behavior, chloride migration, accelerated carbonation, gas permeability, desorption isotherms, porosity) are discussed and a statistical analysis was performed to characterize these results through appropriate probability density functions

A Randomized Comparison of High Clopidogrel Loading Doses in Patients With Non–ST-Segment Elevation Acute Coronary Syndromes The ALBION (Assessment of the Best Loading Dose of Clopidogrel to Blunt Platelet Activation, Inflammation and Ongoing Necrosis) Trial

ObjectivesWe sought to compare the antiplatelet effects of three clopidogrel loading doses (LDs).BackgroundAdministration of a 300-mg clopidogrel LD is beneficial in situations requiring rapid platelet inhibition. Whether higher LDs can provide further benefits remains unknown.MethodsPatients (n = 103) with non–ST-segment elevation acute coronary syndromes were randomized to receive a 300-mg, 600-mg, or 900-mg clopidogrel LD, given on top of other standard therapy (including acetylsalicylic acid). The main outcome measure was inhibition of adenosine diphosphate-induced inhibition of platelet aggregation (IPA); inhibition of platelet activation, inflammatory markers, troponin I release, and major adverse cardiac events also were evaluated; all measures were blindly evaluated.ResultsCompared with the 300-mg LD, greater doses were associated with significantly greater platelet inhibition, with dose-effect relationships observed for onset of action, maximal plateau, 24-h areas under the curves of IPA, and rates of low IPA (<10% at 6 h), using 20 μmol/l major adverse cardiac events. A significant dose-response was also observed for the vasodilator-stimulated phosphoprotein index, a measure of P2Y12receptor inhibition. Similar but nonsignificant trends were observed for troponin release and major adverse cardiac events. Bleeding rates were similar in each group.ConclusionsIn low-to-moderate risk patients with non–ST-elevation acute coronary syndromes, clopidogrel LDs >300 mg provide a faster onset of action, a higher IPA plateau, and greater reductions in platelet activation during the first 24 h. A 900-mg LD may induce a greater antiplatelet effect than 600 mg, when compared with the standard 300-mg regimen. These findings require further clinical confirmation