Singular Values, Nematic Disclinations, and Emergent Biaxiality

Both uniaxial and biaxial nematic liquid crystals are defined by orientational ordering of their building blocks. While uniaxial nematics only orient the long molecular axis, biaxial order implies local order along three axes. As the natural degree of biaxiality and the associated frame, that can be extracted from the tensorial description of the nematic order, vanishes in the uniaxial phase, we extend the nematic director to a full biaxial frame by making use of a singular value decomposition of the gradient of the director field instead. New defects and degrees of freedom are unveiled and the similarities and differences between the uniaxial and biaxial phase are analyzed by applying the algebraic rules of the quaternion group to the uniaxial phase.Comment: 5 pages, 1 figure, submitted to PR

Mythologizing a 'Zone City': Urban Fantasies of and in Songdo, South Korea

Songdo is a city built within Koreas first Free Economic Zone (FEZ). The city has become imbued with three distinct yet interrelated fantasies a grand state project envisioned to guide the country towards modernity; a blank slate onto which an organized and efficient utopian community can be built; and an urban node in a frictionless world. In this thesis, I present an anthropology of and in the city by exploring the relations between the urban imagination of Songdo and particular groups in the city. I argue that Songdos fantasies shape the behaviours, perceptions, and material practices of people working and living in the city, who in turn interpret and act upon Songdos physical and symbolic spaces. I attempt to demonstrate that while Songdos mythologies and their concomitant practices link to global trends, the production and experiences of the city reflect a situated and locally embedded urban form

CO excitation in four IR luminous galaxies

The correlation between the CO and far infrared luminosities of spiral galaxies is well established. The luminosity ration, L sub FIR/L sub CO in IR luminous active galaxies is, however, systematically five to ten times higher than in ordinary spirals and molecular clouds in our Galaxy. Furthermore, the masses of molecular hydrogen in luminous galaxies are large, M (H2) approx. equals 10(exp 10) solar magnitude, which indicates the observed luminosity ratios are due to an excess of infrared output, rather than a deficiency of molecular gas. These large amounts of molecular gas may fuel luminous galaxies through either star formation or nuclear activity. This interpretation rests on applying the M (H2)/L sub CO ratio calibrated in our Galaxy to galaxies with strikingly different luminosity ratios. But are the physical conditions of the molecular gas different in galaxies with different luminosity ratios. And, if so, does the proportionality between CO and H2 also vary among galaxies. To investigate these questions researchers observed CO (2 to 1) and (1 to 0) emission from four luminous galaxies with the Institute for Radio Astronomy in the Millimeter range (IRAM) 30 m telescope. Researchers conclude that most of the CO emission from these Arp 193, Arp 220, and Mrk 231 arises in regions with moderate ambient densities similar to the clouds in the Milky Way molecular ring. The emission is neither from dense hot cloud cores nor from the cold low density gas characteristic of the envelopes of dark clouds

The treatment of mixing in core helium burning models - I. Implications for asteroseismology

The detection of mixed oscillation modes offers a unique insight into the internal structure of core helium burning (CHeB) stars. The stellar structure during CHeB is very uncertain because the growth of the convective core, and/or the development of a semiconvection zone, is critically dependent on the treatment of convective boundaries. In this study we calculate a suite of stellar structure models and their non-radial pulsations to investigate why the predicted asymptotic g-mode $\ell = 1$ period spacing $\Delta\Pi_1$ is systematically lower than is inferred from Kepler field stars. We find that only models with large convective cores, such as those calculated with our newly proposed "maximal-overshoot" scheme, can match the average $\Delta\Pi_1$ reported. However, we also find another possible solution that is related to the method used to determine $\Delta\Pi_1$: mode trapping can raise the observationally inferred $\Delta\Pi_1$ well above its true value. Even after accounting for these two proposed resolutions to the discrepancy in average $\Delta\Pi_1$, models still predict more CHeB stars with low $\Delta\Pi_1$ ($< 270$ s) than are observed. We establish two possible remedies for this: i) there may be a difficulty in determining $\Delta\Pi_1$ for early CHeB stars (when $\Delta\Pi_1$ is lowest) because of the effect that the sharp composition profile at the hydrogen burning shell has on the pulsations, or ii) the mass of the helium core at the flash is higher than predicted. Our conclusions highlight the need for the reporting of selection effects in asteroseismic population studies in order to safely use this information to constrain stellar evolution theory.Comment: 24 pages. 24 figures. Published in MNRA

Age Study of Minnesota Red Fox Using Cementum Annulae Counts and Tooth X-Rays

A prerequisite to the proper management of an animal species is understanding of its population dynamics. Attempting this, the age structure of 297 red fox trapped or shot in southern Minnesota was investigated, using the techniques of tooth sectioning and x-ray. Results from two seasons (1977 and 1978) were similar, with 76.8 percent of the harvested population being juveniles (78.4 percent, 1977 and 74.6 percent, 1978), whereas only 0 .6 percent of the total were in the 4½ year old class. The percentage of juveniles corresponds closely to the numbers predicted by a Department of Natural Resources model developed by Al Berner of the Farmland Research Unit. If a population reacts in a density-dependent manner, an increase in the breeding density should reduce the reproductive rate, and vice-versa. Data of this paper tend to support the premise that the reproductive rate in Minnesota red fox is affected in a density-dependent manner

Nutritional Status of Psychiatric Inpatients at A National Mental Hospital in Kenya

Malnutrition among psychiatric patients in mental health units stands at 19%. It is a prevailing health care problem, that is affecting many psychiatry patients and it is a major public health problem especially in public hospitals in Kenya. Nutrition care is therefore an important component of mental health that require keen consideration. The goal of the study was to determine the nutritional status of psychiatric inpatients at a National Mental Hospital in Kenya. A cross-sectional design was used and 200 inpatients were recruited to the study using simple random sampling. Data was collected using a structured questionnaire which was adopted and modified from Short Nutritional Assessment Questionnaire (SNAQ) screening tool. Height and weight of the participants were measured and BMI was calculated. Clearance and approval to conduct the study was sought from University of Eastern Africa-Baraton Ethical Review Committee. Results of the study showed that majority of the participants were being treated for schizophrenia (41.5%) followed by drug induced psychosis at 22%. The results of the study also showed that 59.5% of the respondents were well nourished while a significant 40.5% were malnourished. Among the Malnourished patients, 67% had a BMI above 25.00Kg/M2 and 33% had a BMI below18.50Kg/M2. Malnourishment was associated with use of antipsychotic (P=0.021), use of antidepressants (P=0.018). It was also associated with female gender (P=0.001), abuse of cigarettes (P=0.041), abuse of marijuana (P=0.01), abuse of alcohol (P=0.001) and poor appetite (P=0.032). Nutritional management should be a component of the routine inpatient care of psychiatric patients. Keywords: Nutritional status, Psychiatric patients, Malnutrition

DSP-Based Field-Oriented Step Motor Control

The SMC3 motor drive has been built using an Analog Devices ADSP-2101 digital signal processor (DSP). The SMC3 is designed to work with two-phase step motors, which are permanent magnet motors with many (typically 100) poles. The firmware in the SMC3 DSP drives the step motor phase windings using field-oriented control rather than using single steps. This method derives the maximum theoretical performance from the motor. This paper describes field-oriented control, and how the SMC3 hardware and firmware implements it

Synchronous Motor Phase Control By Vector Addition of Induced Winding Voltages

We propose a simple low-cost approach to the winding-sensed control of three-phase synchronous permanent-magnet motors. Our approach results from a straightforward but elegant application of vector-based motor theory. The method therefore does not depend on the differential equations that describe the motor dynamics, and it does not depend on the particular motor parameters. The single method we derive applies to both wye- and delta-configured motors. We vectorially sum the voltage waveforms at the motor terminals in a certain way and use their zero crossings to produce a correctly phased six-step switch sequence. We discuss the implementation for both wye- and delta-configured motors, and we present experimental results for a delta-configured implementation

DSP-Based Field-Oriented Step Motor Control

The SMC3 motor drive has been built using an Analog Devices ADSP-2101 digital signal processor (DSP). The SMC3 is designed to work with two-phase step motors, which are permanent magnet motors with many (typically 100) poles. The firmware in the SMC3 DSP drives the step motor phase windings using field-oriented control rather than using single steps. This method derives the maximum theoretical performance from the motor. This paper describes field-oriented control, and how the SMC3 hardware and firmware implements it