From the sublime to the ridiculous: top physics and minimum bias events in the ATLAS detector at the LHC

This thesis is comprised of two separate physics themes, both of which involve the ATLAS detector situated at the LHC at CERN. The first constituent is a study of the top quark signal in the fully-leptonic channel for proton-proton collisions at a centre-of-mass energy of 10 TeV. Here an event counting analysis is performed based on Monte Carlo simulation. This is supplemented by a study into one of the sources of systematic error. The second component is forward-backward correlations in minimum bias events. For this, there is a Monte Carlo hadron-level comparison of the correlation for 900 GeV centre-of-mass collisions, followed by a comparison of Monte Carlo predictions to data for 900 GeV and 7 TeV collisions. Top Physics A measurement of the fully-leptonic ttbar cross-section in the three decay channels ee, mumu, and emu is performed on ATLAS produced fully simulated pseudo-event data-samples. Selection rates for signal and background events consistent with ATLAS results are found along with the kinematic distributions of selected events. A calculation of the non-hadronic ttbar cross-section, based on the measured cross-sections, will then return the theoretical value of 217:06pb used to generate the original samples, showing the closure of the pseudo-analysis process. A more detailed study is made of the systematic uncertainty arising from variations in the initial (ISR) and final (FSR) state showering models, based on the Pythia event generator. A fast simulation of the ATLAS detector is used with similar object and event selection to the fully simulated case. The effect of ISR variations on the signal is found to be negligible as it is washed out in the subsequent decays of the ttbar system. However, the effect of FSR is found to cause 5% uncertainty in the selected signal events. In addition, in the main background of each of the selection channels the effect of FSR is found to produce variations of up to 30% in well populated channels. The variations in signal and background measurements will then be used to calculate a new estimate of the systematics on the measured ttbar cross-section for each channel. Minimum Bias A detailed study of the forward-backward (FB) correlation and event shapes of a selection of Pythia tunes for pp collisions with CoM = 900 GeV is performed. This includes an investigation into the sources of particle production in generated minimum bias events as well as the component sub-processes in generated minimum bias events. The tunes are found to be practically degenerate (within 10 - 20% variation) for the 'standard' distributions. The inclusion of a new observable, namely the forward-backward correlation, to the standard set is recommended. The study finds that the FB-correlation and its pT and dependent variations are able to discern differences between the selected tunes to a greater degree than the usual inclusive distributions. Further, the FB-correlation is found to be sensitive to the particle production processes within the tunes, an invaluable property for the purposes of generator tuning. A measurement of the forward-backward correlation for pp collision of CoM = 900 GeV and 7 TeV at the LHC using the ATLAS detector is made. The measured correlation is compared to the predicted correlation of several ATLAS centrally produced generator tunes. A correction procedure is developed and validated on the generator samples to correct the generated correlation to the hadron-level correlation. This is then applied to the measured correlation and a comparison of corrected data to the hadron-level predictions of the generated tunes made. The corrected correlations at the two collision energies are compared as well as the calculation of a global correlation at both energies. The measured and corrected correlations are found to lie above the predicted distributions at both energies and across the eta-range. Further investigation of measured correlation using augmented FB-correlations is recommended

Non-Native Discourse about the Goals of the Onondaga Nation’s Land Rights Action

On March 11, 2005, the Onondaga Nation became the last nation of the Haudenosaunee Confederacy to file suit against New York State for what it claims was the illegal seizure of the vast majority of its aboriginal land between 1788 and 1822. The Nation is asking for a declaratory court judgment condemning New York’s actions and recognizing that the Onondagas still bear legal title to their homelands. (Onondaga Nation v. State of New York et al., [2005]:12-14). It argues that the suit is not possessory, but rather is an attempt to regain certain rights to the land. The Onondagas have expressed the hope that a court victory will force New York State to negotiate with them on a number of their long-term political goals (Onondaga Nation v. State of New York et al., Memo in Opposition [2006]:7-8). They have also asserted that their approach to the suit and their goals for a future settlement are deeply rooted in their cultural identity (Berry and Nave 2007: part 1). Many non-Natives in the Syracuse area have lauded the Onondagas for framing the suit in this fashion and have organized to publicly demonstrate support for them (McAndrew 2005). At the same time, no significant organized resistance to the land rights action has yet developed. However, a close examination of non-Natives’ discourse about the goals of the land rights action paints a considerably more complex picture of their reactions to the suit. Data was analyzed from local newspapers, a public educational lecture series entitled “Onondaga Land Rights and Our Common Future,” a written survey conducted at a public festival celebrating Onondaga culture, and from individual interviews and a focus group discussion conducted with non-Native members of the Syracuse community. This research suggests that there have been significant gaps in cross-cultural communication that have led many non-Natives to place greater emphasis on environmental cleanup and the improvement of Native/non-Native relationships than on the many other goals that the Onondagas have identified as being extremely important to them. These non-Natives’ misconceptions about the goals of the suit may derive in part from a dependence on Western stereotypes of Native Americans, particularly that of the Ecological Indian. Over-emphasis of some of the Nation’s goals to the neglect of others poses a potential threat to the many positive steps the Syracuse community has taken toward improving intercultural communication and collaboration

Bright low mass eclipsing binary candidates observed by STEREO

Observations from the Heliospheric Imagers (HI-1) on both the STEREO spacecraft have been analysed to search for bright low mass eclipsing binaries (EBs) and potential brown dwarf transits and to determine the radii of the companions. A total of 9 EB candidates have been found, ranging in brightness from V=6.59 mag to V=11.3 mag, where the radius of the companion appears to be less than 0.4 Rsol, with a diverse range of host temperatures, from 4074 K to 6925 K. Both components of one candidate, BD-07 3648, appear to be less than 0.4 Rsol and this represents a particularly interesting system for further study. The shapes of the eclipses in some cases are not clear enough to be certain they are total and the corresponding radii found should therefore be considered as lower limits. The EBs reported in this paper have either been newly found by the present analysis, or previously reported to be eclipsing by our earlier STEREO/HI-1 results. One of the new objects has subsequently been confirmed using archival SuperWASP data. This study was made possible by using an improved matched filter extraction algorithm, which is described in this paper.Comment: 11 pages, 6 figures, 2 tables, accepted for publication in MNRA

Is bicarbonate in Photosystem II the equivalent of the glutamate ligand to the iron atom in bacterial reaction centers?

Photosystem II of oxygen-evolving organisms exhibits a bicarbonate-reversible formate effect on electron transfer between the primary and secondary acceptor quinones, QA and QB. This effect is absent in the otherwise similar electron acceptor complex of purple bacteria, e.g. Rhodobacter sphaeroides. This distinction has led to the suggestion that the iron atom of the acceptor quinone complex in PS II might lack the fifth and sixth ligands provided in the bacterial reaction center (RC) by a glutamate residue at position 234 of the M-subunit in Rb. sphaeroides,RCs (M232 in Rps. viridis). By site-directed mutagenesis we have altered GluM234 in RCs from Rb. sphaeroides, replacing it with valine, glutamine and glycine to form mutants M234EV, M234EQ and M234EG, respectively. These mutants grew competently under phototrophic conditions and were tested for the formate-bicarbonate effect. In chromatophores there were no detectable differences between wild type (Wt) and mutant M234EV with respect to cytochrome b-561 reduction following a flash, and no effect of bicarbonate depletion (by incubation with formate). In isolated RCs, several electron transfer activities were essentially unchanged in Wt and M234EV, M234EQ and M234EG mutants, and no formate-bicarbonate effect was observed on: (a) the fast or slow phases of recovery of the oxidized primary donor (P+) in the absence of exogenous donor, i.e., the recombination of P+QA− or P+QB−, respectively; (b) the kinetics of electron transfer from QA− to QB; or (c) the flash dependent oscillations of semiquinone formation in the presence of donor to P+ (QB turnover). The absence of a formate-bicarbonate effect in these mutants suggests that GluM234 is not responsible for the absence of the formate-bicarbonate effect in Wt bacterial RCs, or at least that other factors must be taken into account. The mutant RCs were also examined for the fast primary electron transfer along the active (A-)branch of the pigment chain, leading to reduction of QA. The kinetics were resolved to reveal the reduction of the monomer bacteriochlorophyll (τ = 3.5 ps), followed by reduction of the bacteriopheophytin (τ = 0.9 ps). Both steps were essentially unaltered from the wild type. However, the rate of reduction of QA was slowed by a factor of 2 (τ = 410 ± 30 and 47 ± 30 ps for M234EQ and M234EV, respectively, compared to 220 ps in the wild type). EPR studies of the isolated RCs showed a characteristic g = 1.82 signal for the QA semiquinone coupled to the iron atom, which was indistinguishable from the wild type. It is concluded that GluM234 is not essential to the normal functioning of the acceptor quinone complex in bacterial RCs and that the role of bicarbonate in PS II is distinct from the role of this residue in bacterial RCs

The effects of station teaching on academic achievement, attention and focus of students with learning disabilities in an inclusive classroom

The purpose of this study was to investigate the effect of the station model of co-teaching on the academic achievement and attention, focus and engagement of students with learning disabilities, as well as, the students\u27 satisfaction with this model. The study utilized an ABAB single subject design to look at one of the six models developed by Friend and Cook (2004) allowing educators to combine their expertise to meet the needs of students in an inclusive setting. The results reveal the station model of co-teaching to be beneficial for students with learning disabilities in the areas of academic achievement and engagement. The data collected and analyzed on the group show an increase in academic achievement from each baseline to intervention phase as well as from intervention to invention phase. The findings show by the second phase of intervention, student focus and attention occurred over 50% of the time for all students. Positive results were gathered from the student satisfaction survey for station teaching with most students agreeing with the statements relating to its benefits and implementation. Research into the station model for both students with learning disabilities and those without learning disabilities would be beneficial

Italian split-keyboard instruments with fewer than nineteen divisions to the octave

Checklists of (1) surviving Italian harpsichords and virginals with split black keys; (2) similar instruments not known to survive but whose existence can be documented; (3) 26 Italian organs built during the period 1468-1665 that are known to have had split keys. Gives the ranges of these instruments when known. Discusses Frescobaldi\u27s probable involvement with such instruments