Therapeutic emphasis in family care and its effect on the function of the social worker

Thesis (M.S.)--Boston University, 1939. This item was digitized by the Internet Archive

A method for designing robust multivariable feedback systems

A new methodology is developed for the synthesis of linear, time-invariant (LTI) controllers for multivariable LTI systems. The aim is to achieve stability and performance robustness of the feedback system in the presence of multiple unstructured uncertainty blocks; i.e., to satisfy a frequency-domain inequality in terms of the structured singular value. The design technique is referred to as the Causality Recovery Methodology (CRM). Starting with an initial (nominally) stabilizing compensator, the CRM produces a closed-loop system whose performance-robustness is at least as good as, and hopefully superior to, that of the original design. The robustness improvement is obtained by solving an infinite-dimensional, convex optimization program. A finite-dimensional implementation of the CRM was developed, and it was applied to a multivariate design example

Coherent network analysis technique for discriminating gravitational-wave bursts from instrumental noise

Existing coherent network analysis techniques for detecting gravitational-wave bursts simultaneously test data from multiple observatories for consistency with the expected properties of the signals. These techniques assume the output of the detector network to be the sum of a stationary Gaussian noise process and a gravitational-wave signal, and they may fail in the presence of transient non-stationarities, which are common in real detectors. In order to address this problem we introduce a consistency test that is robust against noise non-stationarities and allows one to distinguish between gravitational-wave bursts and noise transients. This technique does not require any a priori knowledge of the putative burst waveform.Comment: 18 pages, 11 figures; corrected corrupted figur

Own-race and own-age biases facilitate visual awareness of faces under interocular suppression

The detection of a face in a visual scene is the first stage in the face processing hierarchy. Although all subsequent, more elaborate face processing depends on the initial detection of a face, surprisingly little is known about the perceptual mechanisms underlying face detection. Recent evidence suggests that relatively hard-wired face detection mechanisms are broadly tuned to all face-like visual patterns as long as they respect the typical spatial configuration of the eyes above the mouth. Here, we qualify this notion by showing that face detection mechanisms are also sensitive to face shape and facial surface reflectance properties. We used continuous flash suppression (CFS) to render faces invisible at the beginning of a trial and measured the time upright and inverted faces needed to break into awareness. Young Caucasian adult observers were presented with faces from their own race or from another race (race experiment) and with faces from their own age group or from another age group (age experiment). Faces matching the observers’ own race and age group were detected more quickly. Moreover, the advantage of upright over inverted faces in overcoming CFS, i.e., the face inversion effect (FIE), was larger for own-race and own-age faces. These results demonstrate that differences in face shape and surface reflectance influence access to awareness and configural face processing at the initial detection stage. Although we did not collect data from observers of another race or age group, these findings are a first indication that face detection mechanisms are shaped by visual experience with faces from one’s own social group. Such experience-based fine-tuning of face detection mechanisms may equip in-group faces with a competitive advantage for access to conscious awareness

Cavity Enhanced Optical Vernier Spectroscopy, Broad Band, High Resolution, High Sensitivity

A femtosecond frequency comb provides a vast number of equidistantly spaced narrow band laser modes that can be simultaneously tuned and frequency calibrated with 15 digits accuracy. Our Vernier spectrometer utilizes all of theses modes in a massively parallel manner to rapidly record both absorption and dispersion spectra with a sensitivity that is provided by a high finesse broad band optical resonator and a resolution that is only limited by the frequency comb line width while keeping the required setup simple.Comment: 11 pages, 3 figures, submitted to PR

Investigation of the properties and reactivity of biocarbons at high temperature in mixture of CO/CO2

The CO2 gasification reactivity of biocarbons produced from birch wood chips under different atmospheric and pressurised conditions was investigated in this work. The reactivity tests were conducted by using a Macro-TGA at 1100°C in a gas mixture of 50% CO2 and 50% CO to simulate the conditions in an industrial ferromagnese furnace. The results showed that biocarbons produced under different conditions have different CO2 gasification reactivities. The biocarbon produced in an atmospheric fixed bed reactor has the highest reactivity. This biocarbon has a high surface area and content of catalytic inorganic elements, which favour the Boudouard reaction and consumes fixed carbon. Scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDS) showed that migration and transformation behaviours of inorganic elements in the studied biocarbons are different at the same gasification condition. Together with inductively coupled plasma atomic emission spectroscopy (ICP-OES) analysis, SEM-EDS analysis revealed that the most intensive transformation of inorganic elements occurred during gasification of the biocarbon sample produced at atmospheric conditions with slow heating rate and purging of N2. Such pyrolysis condition promotes presence of catalytic inorganic elements on the biocarbon surface, which promotes the Boudouard reaction.publishedVersio

Investigation of gasification reactivity and properties of biocarbon at high temperature in a mixture of CO/CO2

Understanding the conversion behaviors of biocarbon under conditions relevant to industrial conditions is important to ensure proper and efficient utilization of the biocarbon for a dedicated metallurgical process. The present work studied the reactivity of biocarbon by using a Macro-TGA at 1100 °C in a gas mixture of CO2 and CO to simulate the conditions in an industrial closed submerged arc manganese alloy furnace. The conversion residues from the Macro-TGA tests were collected for detailed characterization through a combination of different analytical techniques. Results showed that biocarbons produced under various conditions have different reactivities under the studied conditions. The biocarbon produced in an atmospheric fixed bed reactor with continuous purging of N2 has the highest reactivity. Its fixed carbon loss started as the gas atmosphere shifted from the inert Ar to a mixture of CO and CO2 at 1100 °C. And only 450 s was needed to reach a desired fixed-carbon loss of 20%. The high reactivity of the biocarbon is mainly related to its porous structure and high content of catalytic inorganic elements, which favor gasification reactions of the carbon matrix towards the surrounding gas atmosphere and consumption of carbon consequently. In contrast, biocarbon produced under constrained conditions and from wood pellets and steam exploded pellets have more compact appearance and dense structures. Significant fixed carbon loss for these biocarbons started 80–200 s later than that of the biocarbon produced at atmospheric conditions with purging of N2. Additionally, it took longer time, 557–1167 s, for these biocarbons to realize the desired fixed-carbon loss. SEM-EDX analyses results revealed clear accumulation and aggregation of inorganic elements, mainly Ca, on the external surface of the residues from gasification of biocarbon produced in the fixed bed reactor with purging of N2. It indicates more intensive migration and transformation of inorganic elements during gasification at this condition. This resulted in formation of a carbon matrix with more porous structure and active sites on the carbon surface, promoting the Boudouard reaction and conversion of carbon.publishedVersio

Swift observations of the very intense flaring activity of Mrk 421 during 2006: I. Phenomenological picture of electron acceleration and predictions for the MeV/GeV emission

We present results from a deep spectral analysis of all the Swift observations of Mrk 421 from April 2006 to July 2006, when it reached its largest X-ray flux recorded until 2006. The peak flux was about 85 milli-Crab in the 2.0-10.0 keV band, with the peak energy (Ep) of the spectral energy distribution (SED) laying often at energies larger than 10 keV. We performed spectral analysis of the Swift observations investigating the trends of the spectral parameters in terms of acceleration and energetic features phenomenologically linked to the SSC model parameters, predicting their effects in the gamma-ray band, in particular the spectral shape expected in the Fermi Gamma-ray Space Telescope-LAT band. We confirm that the X-ray spectrum is well described by a log-parabolic distribution close to Ep, with the peak flux of the SED (Sp) being correlated with Ep, and Ep anti-correlated with the curvature parameter (b). During the most energetic flares the UV-to-soft-X-ray spectral shape requires an electron distribution spectral index s about 2.3. Present analysis shows that the UV-to-X-ray emission from Mrk 421 is likely to be originated by a population of electrons that is actually curved, with a low energy power-law tail. The observed spectral curvature is consistent both with stochastic acceleration or energy dependent acceleration probability mechanisms, whereas the power-law slope form XRT-UVOT data is very close to that inferred from the GRBs X-ray afterglow and in agreement with the universal first-order relativistic shock acceleration models. This scenario hints that the magnetic turbulence may play a twofold role: spatial diffusion relevant to the first order process and momentum diffusion relevant to the second order process.Comment: Accepted, Astronomy and Astrophysic