A nonparametric regression cross spectrum for multivariate time series

We consider dependence structures in multivariate time series that are characterized by deterministic trends. Results from spectral analysis for stationary processes are extended to deterministic trend functions. A regression cross covariance and spectrum are defined. Estimation of these quantities is based on wavelet thresholding. The method is illustrated by a simulated example and a three-dimensional time series consisting of ECG, blood pressure and cardiac stroke volume measurements.Nonparametric trend estimation, cross spectrum, wavelets, regression spectrum, phase, threshold estimator

Estimation of a nonparametric regression spectrum for multivariate time series

Estimation of a nonparametric regression spectrum based on the periodogram is considered. Neither trend estimation nor smoothing of the periodogram are required. Alternatively, for cases where spectral estimation of phase shifts fails and the shift does not depend on frequency, a time domain estimator of the lag-shift is defined. Asymptotic properties of the frequency and time domain estimators are derived. Simulations and a data example illustrate the methods.Periodogram, cross spectrum, regression spectrum, phase, wavelets.

Drugs and alcohol management and testing standards in Australian workplaces: avoiding that “morning-after” feeling

Dissertação de mestrado em Evolução e Biologia Humana, apresentada ao Departamento de Ciências da Vida da Faculdade de Ciências e Tecnologia da Universidade de Coimbra.O presente trabalho tem como objetivo estudar os restos ósseos humano exumados de nove fossas e um nicho de Torre Velha 3 (São Salvador, Serpa) datados do Calcolítico e da Idade do Bronze. Esta análise pretende dar um contributo para um conhecimento mais completo da realidade funerária da pré-história recente no Sudoeste Peninsular e das populações humanas que o compõem. Ainda que houvesse um predomínio de enterramentos individuais algumas estruturas continham enterramentos duplos (n= 2) datados da Idade do Bronze. Não foi detetado qualquer padrão na orientação dos esqueletos enquanto a deposição mostrou uma maior predileção pela posição fetal. Desta amostra, sete esqueletos adultos pertencem ao Calcolítico e nove indivíduos (seis adultos, dois adultos jovens e um não-adulto) à Idade do Bronze. Morfologicamente, destacam-se os caracteres discretos pós-cranianos como a presença de abertura septal (n=2) e de calcâneos secundários (n= 2) na amostra do Calcolítico e, perfuração supraclavicular (n= 2/7) e duas fossas hipotrocanterianas (n= 2/5) nos indivíduos pertencentes à Idade do Bronze. Nos dentários, realça-se a completa ausência da cúspide de Carabelli (n= 10) nos dois períodos cronológicos desta amostra. Na análise patológica algumas alterações osteofíticas a nível da entese foram registadas, sendo que tanto na amostra Calcolítica (n= 1/2) como na da Idade do Bronze (n= 5/9) se denota uma predomínio de alteração na zona do músculo braquioradialis, assim como no ligamento conóide. A patologia dentária revelou para o Calcolítico uma frequência de 7,96% (n= 9/113) de cáries e para a Idade do Bronze 4,14% (n= 8/193). Os depósitos de tártaro são baixos em ambos os períodos e com um desgaste dentário médio de 3,03 (n= 111) para os indivíduos do Calcolítico e 2,69 (n= 193) para os da Idade do Bronze. É de salientar um desgaste dentário tipo polimento verificado nos dentes de alguns indivíduos do Calcolítico (4,50% n= 5/111) e, ainda, alterações dentárias aparentemente por uso extramastigatório, como a presença de pequenos sulcos na superfície incisal/oclusal (Calcolítico: 3,6 n= 4/111; Idade do Bronze: 2,07 n= 4/193).This work aims to study the human skeletal remains exhumed nine pits and one niche from Torre Velha 3 (São Salvador, Serpa) dating from the Chalcolithic and Bronze Age. This analysis intends to contribute towards a fuller knowledge of the funeral reality in the recent prehistory of the Southwest Iberian Peninsula and of the human populations that composed it. Although there was a predominance of individual burials, some structures contained double burials (n = 2) dating from the Bronze Age. No pattern in the orientation of the skeletons was detected although in terms of the deposition a greater preference for the fetal position was registered. In this sample, seven adult skeletons belong to the Chalcolithic and nine individuals (six adults, two young adults and one non-adult) to the Bronze Age. Morphologically, regarding post-cranial discrete traits, septal opening (n = 2) and calcaneus secundarius (n = 2) were present in the Chalcolithic sample and supraclavicular perforation (n = 2/7) and two hipotrochanteric fossa (n = 2/5) were registered in the individuals belonging to the Bronze Age. In what concerns dental discrete traits, the complete absence of the Carabelli cusp (n = 10) must be highlighted in the two chronological periods analysed in this sample. The pathological analysis revealed some osteophytics changes in the enthesis, and both the sample from the Chalcolithic (n = 1/2) and from the Bronze Age (n = 5/9) denote a prevalence of this condition in the braquioradialis muscle area as well as the conoid ligament. Dental pathology revealed a rate of 7.96% (n = 9/113) of caries for the Chalcolithic sample and 4.14% (n = 8/193) for the Bronze Age one. Tartar deposits are low in both periods and dental wear presents an average of 3.03 (n = 111) for the Chalcolithic individuals and 2.69 (n = 193) for the Bronze Age ones. A dental wear of a polishing type was identified in the teeth of some individuals from the Chalcolithic (4.50% n = 5/111) and dental changes apparently caused by extra-masticatory use, such as the presence of small grooves on the incisal surface / occlusal (Chalcolithic: 3.6 n = 4/111; Bronze Age: 2.07 n = 4/193) should be highlighted

Replacing a corrugated carton with a multiwall paper bag for food wraps

The objective of this study was to determine the feasibility of replacing a corrugated container with a multiwall paper bag for the packaging of food wraps used in the Quick - Serve foodservice industry. The study was limited to one specific restaurant chain and for only one size of food wraps. Laboratory testing was used to compare the performance attributes of both package systems. This study will provide a model for quantifying package source reduction when comparing a rigid package design to a flexible one. The results show that, indeed, a multiwall paper bag is a feasible alternative to a corrugated container when packaging food wraps and that significant source reduction can be realized from this change. Immediate and significant cost savings will also be achieved if the alternate package system is used for this foodservice application

Influence of particle and photon fluxes of hydrogen plasmas on the work function of caesiated surfaces

Modern high-power negative hydrogen ion sources rely predominantly on the surface production of negative hydrogen ions. For this, a low work function of the extraction electrode surface is required to effectively convert impinging atoms and positive ions from low pressure low temperature hydrogen plasmas into negative ions. The state-of-the-art technique for the generation of low surface work functions is in situ evaporation of the alkali metal Cs, which exhibits a bulk work function of 2.0–2.1 eV. However, the achievement of a temporally stable and reliable low work function coating is challenging in an ion source environment due to the influence of the reactive hydrogen particles (atoms and positive ions) and energetic UV/VUV photons (up to 15 eV) during plasma phases as well as residual gases during vacuum phases. At RF driven ion sources for neutral beam injection systems for nuclear fusion where in the case of the ITER experiment pulse lengths up to one hour are required, temporal instabilities of the source performance are a major issue and especially problematic in deuterium operation. Since work function measurements at negative ion sources are challenging and not routinely applied, investigations on the work function dynamics of caesiated surfaces upon exposure to ion source relevant particle and photon fluxes are gained at a dedicated laboratory experiment. The experiment is equipped with a finely adjustable Cs oven allowing in situ caesiation of surfaces installed at a sample holder. A comprehensive set of diagnostics is available for the determination of fluxes to which the surface is exposed in vacuum and plasma phases, and the surface work function is measured by the exploitation of the photoelectric effect. Within this work, the accuracy of the work function diagnostic is significantly improved by lowering the detection limit for photocurrents by several orders of magnitude. Furthermore, the experimental setup is extended by an external plasma source with which the surface under investigation can be exposed to fluxes of specific hydrogen plasma species. The application of the improved work function diagnostic reveals that ultra-low work functions in the range of 1.2–1.3 eV can be reproducibly generated under the typically given non-ultra-high vacuum conditions where water is the dominant residual gas. The work function is found to be dependent on the flux ratio of Cs to water onto the surface, and the achieved work function of significantly below that of bulk Cs is attributed to the formation of Cs oxide layers due to reactions between Cs and water at the surface. The work function behavior upon re-caesiation after operational breaks, upon heat as well as upon exposure to various gas species is studied in detail, allowing the identification of beneficial and detrimental influences on the caesiation process. In order to investigate the role of the different plasma species in the plasma-surface interaction, caesiated surfaces are selectively exposed to VUV photons, hydrogen atoms and positive hydrogen ions using the external plasma source. It is shown that each species can affect the surface separately, demonstrating for the first time that photonic, atomic as well as ionic interactions must be considered in the plasma-surface interaction. The full plasma-surface interaction is investigated by the ignition of plasmas in front of the caesiated surface, where scenarios with plasma pulses ranging from a few seconds up to several hours with and without Cs evaporation both in hydrogen and deuterium are applied. It is shown that ultra-low work function layers can be reliably generated but are not stable upon plasma exposure exceeding one minute, which explains the observed deterioration of the ion source performance in long pulses. During steady-state plasma operation, a minimum work function of 1.8 eV is found to be stable for sufficiently high Cs fluxes onto the surface both in hydrogen and deuterium and independent of the initial work function in the vacuum phase

Natural Image Statistics for Natural Image Segmentation

Building on recent progress in modeling filter response statistics of natural mages we integrate a statistical model into a variational framework for image segmentation. Incorporated in asound probabilistic distance measure the model drives level sets toward meaningful segment at ions of complex textures and natural scenes. Despite its enhanced descriptive power our approach preserves the efficiency of level set based segmentation since each connected region comprises two model parameters only. We validate the statistical basis of our model on thousands of natural images and demonstrate that our approach outperforms recent variational segment at ion methods based on second-order statistics