Dynamics between organic molecules and surface enhanced Raman scattering (SERS) hot spots are extracted from far-field optical images by two experimental methods presented in this thesis: orientational imaging and super-resolution optical imaging. We introduce SERS orientational imaging as an all-optical technique able to determine the three-dimensional orientations of SERS-active Ag nanoparticle dimers. This is accomplished by observing lobe positions in SERS emission patterns formed by the directional polarization of SERS emission along the longitudinal axis of the dimer. We further extend this technique to discriminate nanoparticle dimers from higher order aggregates by observing the wavelength-dependence of SERS emission patterns, which are unchanged in nanoparticle dimers, but show differences in higher order aggregates involving two or more nanoparticle junctions. Dynamic fluctuations in the SERS emission pattern lobes are observed in aggregates labeled with low dye concentrations, as molecules diffuse into regions of higher electromagnetic enhancement in multiple nanoparticle junctions. In order to investigate these dynamic interactions between single organic molecules and nanoparticle hot spots we present the first super-resolution optical images of single-molecule SERS (SM-SERS), introducing super-resolution imaging as a powerful new tool for SM-SERS studies. Mapping the dynamic movement of SM-SERS centroid positions with +/- 5 nm resolution reveals the position-dependent SERS intensity as the centroid samples different positions in space. We have proposed that the diffusion of the SERS centroid is due to diffusion of a single molecule on the surface of the nanoparticle, which leads to changes in coupling between the scattering dipole and the optical near field of the nanoparticle. Finally, we combine an isotope-edited bi-analyte SERS spectral approach with super-resolution optical imaging and atomic force microscopy (AFM) structural analysis for a more complete picture of molecular dynamics in SERS hot spots. We demonstrate the ability to observe multiple molecule dynamics in a single hot spot and show that in addition to the single-molecule regime, a "few" molecule regime is able to report on position-dependent SERS intensities in a hot spot. Furthermore, we are able to identify multiple local hot spots in single nanoparticle aggregates. / text

Reading of messenger RNA (mRNA) by aminoacyl-tRNAs (aa-tRNAs) on the ribosomes in the bacterial cell occurs with high accuracy. It follows from the physical chemistry of enzymatic reactions that there must be a trade-off between rate and accuracy of initial tRNA selection in protein synthesis: when the current accuracy, the A-value, approaches its maximal possible value, the d-value, the kinetic efficiency of the reaction approaches zero. We have used an in vitro system for mRNA translation with purified E. coli components to estimate the d- and A-values by which aa-tRNAs discriminate between their cognate and near cognate codons displayed in the ribosomal A site. In the case of tRNALys, we verified the prediction of a linear trade-off between kinetic efficiency of cognate codon reading and the accuracy of codon selection. These experiments have been extended to a larger set of tRNAs, including tRNAPhe, tRNAGlu, tRNAHis, tRNACys, tRNAAsp and tRNATyr, and linear efficiency-accuracy trade-off was observed in all cases. Similar to tRNALys, tRNAPhe discriminated with higher accuracy against a particular mismatch in the second than in the first codon position. Remarkably high d-values were observed for tRNAGlu discrimination against a C-C mismatch in the first codon position (70 000) and for tRNAPhe discrimination against an A-G mismatch in the second codon position (79 000). At the same time, we have found a remarkably small d-value (200) for tRNAGlu misreading G in the middle position of the codon (U-G mismatch). Aminoglycoside antibiotics induce large codon reading errors by tRNAs. We have studied the mechanism of aminoglycoside action and found that the drug stabilized aminoacyl-tRNA in a codon selective in relation to a codon non-selective state. This greatly enhanced the probability of near cognate aminoacyl-tRNAs to successfully transcend the initial selection step of the translating ribosome. We showed that Mg2+ ions, in contrast, favour codon non-selective states and thus induce errors in a principally different way than aminoglycosides.  We also designed experiments to estimate the overall accuracy of peptide bond formation with, including initial selection accuracy and proofreading of tRNAs after GTP hydrolysis on EF-Tu. Our experiments have now made it possible to calibrate the accuracy of tRNA selection in the test tube to that in the living cells. We will now also be able to investigate the degree to which the accuracy of tRNA selection has been optimized for maximal fitness.

No description available.

The Utah Department of Transportation (UDOT) Traffic and Safety Division continues to advance the safety of roadway sections throughout the state. To aid UDOT in meeting their goal the Department of Civil and Environmental Engineering at Brigham Young University (BYU) has worked with the Statistics Department in developing analysis tools for safety. The most recent of these tools has been the development of a hierarchical Bayesian Poisson Mixture Model (PMM) statistical model of traffic crashes and safety on UDOT roadways statewide and the integration of the results of this model in a Geographic Information System (GIS) framework. This research focuses on the enhancement of the framework for highway safety mitigation in Utah with its six primary steps: 1) network screening, 2) diagnosis, 3) countermeasure selection, 4) economic appraisal, 5) project prioritization, and 6) effectiveness evaluation. The framework was enhanced by developing a methodology for accomplishing the steps of network screening, diagnosis, and countermeasure selection. This methodology is titled, "Hot Spot Identification and Analysis." The hot spot identification and analysis methodology consists of the following seven steps: 1) identify problematic segments with safety concern, 2) identify problem spots within the segments, 3) micro analysis of problematic segments and spots, 4) defining the segment, 5) defining the problem, 6) evaluation of possible countermeasures, and 7) selection and recommendation of feasible countermeasures. The methodology is to help in the identification of hot spots with safety concerns so that they can be analyzed and countermeasures can be identified to mitigate the safety issues. Examples of how the methodology is to function are given with specific examples from Utah's state roadway network.

In January of 2012, Philadelphia Mayor Michael Nutter outlined the crime fighting measures that his administration would pursue during his second term as mayor. Included was a plan to introduce a multi-agency crime reduction program, which Philadelphia Police Commissioner Charles Ramsey and District Attorney Seth Williams would co-chair, called GunStat. GunStat was described as a collaborative effort to reduce gun violence through (1) identifying locations with a high incidence of violent crime, (2) pinpointing violent offenders responsible for these crimes, (3) focusing on arresting and prosecuting these offenders for crimes committed at these places, and (4) enhanced monitoring of offenders on probation and parole who are living and/or offending within these locations. In effect, GunStat was designed to target the right people (prolific, violent known offenders) at the right places (hot spots of violent crime). This dissertation is an in-depth, ex post facto evaluation of Philadelphia’s GunStat model as implemented over two phases and two years. It involved both a quasi-experimental research design which employed propensity score matching methods to generate comparisons, and a process-evaluation where several themes, including program implementation, were explored. The results here suggest that GunStat did not reduce crime relative to comparison locations. However, the qualitative data highlighted the importance of informal inter-agency networks that were developed during the course of the intervention, and suggested that GunStat put future collaborations on a solid footing. The implications for criminal justice policy, theory and evaluation design are discussed. / Criminal Justice

I den här kvantitativa GIS studien har spatiala och temporala koncentrationer/hot spots gällande hög och störande musik från fordon studerats i syfte att undersöka dessa platsers kriminogenitet och gemensamma miljömässiga karaktär samt den sociala kontext som kan vara kopplat till problemet. Studiens resultat visade på tre stabila hot spots men att dessa inte gällde för övrig brottslighet. Platserna kunde därför inte bedömas som kriminogena utom gällande den störande musiken från fordon. Det gemensamma för dessa platser visades vara närheten till genomfartsleder, parkeringsplatser och bensinpumpar. Studien kommer fram till att syftet med att spela musiken inte är att störa andra, utan om att ha kul, hänga med likasinnade, skapa identitet och visa sin kultur genom att synas och höras. Och att valet av plats inte beror på något annat än att de är geografiskt och bekvämt belägna och har de egenskaperna och attribut som passar dessa sammankomster. / This quantitative paper contains a spatial and temporal GIS-analysis regarding hot spots of loud and disturbing music from vehicles, in order to investigate the criminogenic and environmental character of these occurrences, as well as the social context that may be linked to the problem. The results of the study showed three stable hot spots but also that these hot spots did not apply to other crime, the locations could therefore not be judged as criminogenic except for the disturbing music from vehicles. What these places had in common was the proximity to thoroughfares, parking lots and petrol pumps. The study concludes that the purpose of playing music loud is not to disturb others, rather having fun, hanging out with like-minded people, and creating identity and acting out culture by being seen and heard. And that the reason these events happen in these places is not due to anything other than that they are geographically and conveniently located, and they also have the necessary characteristics to suit such gatherings.

Covid-19 har påverkat hela världen och fokus har legat på att minska smittspridningen. I Sverige har detta föranlett att ett alkoholförbud infördes i november 2020, vilket begränsat serveringsställens öppettider. Hur pandemin och dess förbud har påverkat brottsligheten är ett relativt outforskat område och det finns enligt författarnas kännedom ingen studie om alkoholförbudets effekter. Denna studie ämnar undersöka vilken påverkan som förbudet haft på polisens arbete på mikroplatser samt nivåerna av våld i offentlig miljö och antal omhändertaganden enligt LOB i Malmö stad. Studien har såväl en kvalitativ som kvantitativ ansats. Empirin har samlats in genom semistrukturerade intervjuer med fem poliser och anmälningsstatistik mellan 2017–2021 över våld i offentlig miljö och omhändertaganden enligt LOB. Resultaten visar att de intervjuade poliserna upplever att alkoholförbudet minskat folkmängden på mikroplatserna i nöjesmiljöer och att det föranlett såväl en förskjutning av arbetstider som resursförflyttning. De är även av uppfattningen att berusningsgraden och det offentliga våldet på mikroplatserna har minskat efter alkoholförbudet. Däremot visar statistiken att nivåerna över offentligt våld är oförändrade, vilket kan innebära att platsen för brottet förändrats. Enligt såväl de intervjuade poliserna som statistiken över antal genomförda LOB:ar har det efter alkoholförbudet skett en avsevärd minskning, jämfört med tidigare år. Alkoholförbudet tycks därmed ha inneburit att rutinaktiviteter förändrats och att våldet begås på andra platser än på de mikroplatser där polisen arbetar. För att kunna dra säkra slutsatser om pandemin och dess restriktioners påverkan på brottsligheten behövs studier som kan undersöka dess långsiktiga effekter. / Covid-19 has affected the entire world and the main focus has been on reducing the spread of the virus. An alcohol restriction policy was implemented in Sweden as of November 2020, which has limited the opening hours of serving establishments. How the pandemic and its restrictions has affected crime has not been widely examined and there are to the authors knowledge no studies about the effects of the alcohol restriction. This study aims to look into what impact the restriction has had on the work of the police at hot spots and the levels of public violence and the number of people taken into custody in accordance with LOB in the city of Malmö. The study has a qualitative and quantitative approach. The data was collected through semi-structured interviews with five police officers and statistics of reported levels of public violence between 2017-2021 and the number of people taken into custody in accordance with LOB. The results show that the interviewees experience that the alcohol restriction has reduced the amount of people at hot spots located in entertainment environments and caused their working hours to change and resources to relocate. They are also of the perception that the intoxication level and public violence at the hot spots has decreased after the alcohol restriction. On the contrary, no changes of the levels of public violence has been identified in the analyzed statistics, which can indicate that the violence has relocated. According to both the interviewees and statistics, the number of people taken into custody in accordance with LOB has significantly decreased after the alcohol restriction, compared to previous years. The alcohol restriction may have changed people’s routine activities and that the violence is committed at other locations than at the hot spots. Further studies are needed to be able to make certain conclusions about the long-term effects of the pandemic and its restrictions on crime.

Although hot spots policing has become one of the most promising policing strategies, the empirical evidence on the effectiveness of hot spots policing does not suggest what police should be doing in crime hot spots. To date, police enforcement actions – pedestrian investigations, traffic enforcement, and arrests – still dominate American policing. Yet empirical studies of these actions have not: focused on micro-geographic areas, employed multiple measures of police enforcement actions, or empirically compared the effectiveness of different enforcement actions. Given these gaps in the literature, a mixed-methods study sought to answer four research questions. (1) Do four police enforcement actions focused on offenders or potential offenders reduce violent crime in hot spots? The four police enforcement actions examined were pedestrian investigations, traffic enforcement events, quality of life arrests, and violent crime arrests. (2) Are any one of these four police enforcement actions more effective than the others? (3) When police commanders allocate resources to crime hot spots, what do police commanders think they are doing? (4) What are police commanders’ rationales for what they do in crime hot spots? The first two questions were answered using official data from the Philadelphia Police Department. A purposive sample of 169 high crime street blocks and intersections was drawn and longitudinal data analyses examined the effects of police enforcement actions on monthly violent crime counts from 2009 to 2013 (n = 10,140). Wald Tests were used to test for the differential effectiveness of the four enforcement actions. Qualitative methods answered the remaining two research questions. Field observations of crime strategy meetings (May, 2014 to August, 2014) and interviews with police commanders (November, 2014 to February, 2015) were conducted. The quantitative results found total enforcement and pedestrian stop levels in the previous or same month linked to higher expected monthly violent crime counts. The positive effect of pedestrian stops was significantly larger than the effects of traffic enforcement or quality of life arrests. Despite the positive relationship between police enforcement and violent crime, the qualitative results provided insight into what police commanders thought they were doing in crime hot spots. Three themes emerged from the qualitative data: (1) “locking down” crime hot spots, (2) disrupting high risk offenders, and (3) educating potential victims. Police commanders rationalized these beliefs with four explanations of their effectiveness: (1) making offenders “think twice”, (2) denying potential offenders and victims certain places in order to reduce crime opportunities, (3) getting high risk offenders “off the street”, and (4) target hardening. Drawing on theorizing for how police enforcement actions might actually link to higher levels of crime (Grabosky, 1996) and methodological concerns raised by Taylor (2015), five possible explanations for the observed positive relationships among police enforcement actions and violent crime are provided: (1) an anticipatory effect, (2) over-deterrence, (3) escalation, (4) unintended enticement and self-fulfilling prophecies, and (5) temporal scaling. The anticipatory effect explanation centers on the police correctly anticipating outbreaks of violent crime but violent crime still not being reduced due to (1) dosage, (2) the overuse of enforcement, (3) police legitimacy, (4) temporal displacement or two components the study’s design (5) imprecise measurement and (6) lack of a proper counterfactual. Additionally, police enforcement actions may inadvertently reduce guardianship though over-deterrence, escalate competition among rival offenders, or inform potential offenders of crimes they could or “should” be committing. Finally, the study’s temporal scale (i.e., months) may not be fine enough to capture the actual cycling of how increased enforcement actions produce lower violent crime levels. The qualitative data are drawn upon to possibly support these explanations. Additionally, the pros and cons of police commanders’ perspectives on the use and effectiveness of enforcement actions are discussed in context of the criminological theory and crime control literatures. Finally, the results are discussed in terms of their implications for crime control theory and policy. / Criminal Justice

A síntese e caracterização de sistemas hetero-híbridos gerados a partir da 3,6-bi-2-piridil-1,2,4,5-tetrazina (bptz) e interações com ouro nanoparticulado são abordados nesta tese. O bptz foi estudado por meio de métodos espectroscópicos e teóricos, focalizando principalmente o efeito SERS associado à adsorção em nanopartículas de ouro. O mecanismo de transferência de carga para metais macroscópicos foi transposto para a condição nanoparticulada, envolvendo ligações químicas entre bptz e as nanopartículas. Os complexos estudados possuem fórmula geral [LmRu(µ-bptz)RuLm]Xn, com “L” indicando os ligantes periféricos 5-cloro-1,10-fenantrolina (Clphen) ou 4’-(fenil)-2,2&#8217:6&#8217,2&#8221-terpirdina (ptpy) e “X” os contra-íons. Foram investigadas suas espectroeletroquímicas eletrônica e SERS, e as mudanças de perfil vibracional foram modeladas, incorporando o mecanismo de transferências de carga entre complexo e o ouro, além dos mecanismos ressonantes e eletromagnéticos / The synthesis and investigation of heterohybrid systems encompassing 3,6-bi-2-pyridyl-1,2,4,5-tetrazine (bptz) and its ruthenium complexes associated with gold nanoparticles are dealt with in this thesis. Bptz was characterized by spectroscopic and theoretical techniques, focusing on its SERS spectra after the adsorption onto nanoparticles. The charge transfer mechanism in the SERS spectra of macroscopic metals was transposed to the nanoparticle condition, assuming the formation of chemical bonds between bptz and the nanoparticles. Complexes of general formula [LmRu(µ--bptz)RuLm]Xn, “L” the peripheric ligants 5-chlorine-1,10-phenantroline or 4’-(phenyl)-2,2&#8217:6&#8217,2&#8221-terpyrdine (ptpy), and “X” counter-ions were also investigated, with special emphasis on their electronic and SERS spectroelectrochemistry. The changes in the vibrational profiles were successfully explained by the occurrence of charge transfer between the adsorbed complex and gold, in addition to the electromagnetic and resonance mechanisms.

O objetivo desse trabalho é apresentar o desenvolvimento de modelos numéricos baseados no método dos elementos finitos, para investigar o comportamento termoelástico, de um freio a tambor utilizado em veículos pesados. O acoplamento de fenômenos físicos e mecânicos durante o processo de frenagem é uma etapa fundamental para o projeto com foco em confiabilidade. A identificação de falhas potenciais decorrentes dos diferentes processos de frenagens, ainda na fase do projeto preliminar, permite o desenvolvimento de projetos mais robustos, incluindo reduções de tempo e nos custos de ensaios experimentais. Este trabalho apresenta o desenvolvimento e implementação de um modelo computacional baseado no comportamento termoelástico dos principais elementos mecânicos de um freio a tambor envolvidos no processo de frenagem. Foram consideradas três condições principais de análise: estática de corpos rígidos, estática de corpos flexíveis e dinâmica em regime permanente com corpos flexíveis. O objetivo é investigar e estimar valores de pressão de contato, cargas resultantes nos apoios, bem como obter o gradiente de temperatura e tensão devido à carga térmica em regiões de interesse. Essa análise pode melhorar o entendimento dos fenômenos envolvidos nos diferentes processos de frenagens, auxiliando as tomadas de decisões técnicas, principalmente na antecipação de falhas prematuras relacionadas com fadiga térmica e desgaste adesivo. / This work presents the development of a numerical model based on thermoelastic behavior of a drum brake applied to heavy vehicles. The coupling of physics and mechanical phenomena during the braking process represents an important phase in the design vehicle systems. The identification of potential failures during the braking processes, considering the preliminary design phase gives robustness to the design. This characteristic allows reducing the time and cost of experimental set-up. This work presents the development and preliminary results of a numerical model based on thermal-elastic behavior of an automotive drum brake. It was considered three main conditions for the analysis: rigid bodies statics, flexible bodies statics and flexible bodies steady state dynamic analysis. The main objective of this study is investigate and estimate the relationship between the design parameters, as strain, stress as well thermal loads and temperature gradient, in conditions of static and quasi-static steady state regime. The estimative of these parameters to support the technical decisions related to reliability design, mainly to anticipate failures arising to thermal fatigue and adhesive wear.