ON APPROXIMATION OF SMOOTH FUNCTIONS FROM NULL SPACES OF OPTIMAL LINEAR DIFFERENTIAL OPERATORS WITH CONSTANT COEFFICIENTS

For a real valued function f defined on a finite interval I we consider the problem of approximating f from null spaces of differential operators of the form Ln（ψ） =∑k=0^n akψ（k） where the constant coefficients ak C R may be adapted to f.

Electrocardiographic abnormalities among Mexican Americans: Correlations with diabetes, obesity, and the metabolic syndrome

INTRODUCTION: Resting ischemic electrocardiographic abnormalities have been associated with cardio-vascular mortality. Simple markers of abnormal autonomic tone have also been associated with diabetes, obesity, and the metabolic syndrome in some populations. Data on these electrocardiographic abnormalities and correlations with coronary risk factors are lacking among Mexican Americans wherein these conditions are prevalent. This study aimed to evaluate the prevalent resting electrocardiographic abnormalities among community-dwelling Mexican Americans, and to correlate these findings with coronary risk factors, particularly diabetes, obesity, and the metabolic syndrome. METHODS: Study subjects (n = 1280) were drawn from the Cameron County Hispanic Cohort comprised of community-dwelling Mexican Americans living in Brownsville, Texas at the United States-Mexico border. Ischemic electro-cardiographic abnormalities were defined as presence of ST/T wave abnormalities suggestive of ischemia, abnormal Q waves, and left bundle branch block. Parameters that reflect autonomic tone, such as heart rate-corrected QT interval and resting heart rate, were also measured. RESULTS: Ischemic electrocar-diographic abnormalities were more prevalent among older persons and those with hypertension, diabetes, obesity, and the metabolic syndrome. Subjects in the highest quartiles of QTc interval and resting heart rate were also more likely to have diabetes, hypertension, obesity, or the metabolic syndrome. CONCLU- SIONS: Among Mexican Americans, persons with diabetes, obesity, and the metabolic syndrome were more likely to have ischemic electrocardiographic abnormalities, longer QTc intervals, and higher resting heart rates. A resting electrocardiogram can play a complementary role in the comprehensive evaluation of cardiovascular risk in this minority population.

Double Degenerate Stars

Regardless of the formation mechanism, an exotic object, the double degenerate star （DDS）, is introduced and investigated, which is composed of baryonic matter and some unknown fermion dark matter. Different from the simple white dwarfs （WDs）, there is additional gravitational force provided by the unknown fermion component inside DDSs, which may strongly affect the structure and the stability of such kind of objects. Many possible and strange observational phenomena connecting with them are concisely discussed. Similar to the normal WD, this object can also experience thermonuclear explosion as type Ia supernova explosion when DDS＇s mass exceeds the maximum mass that can be supported by electron degeneracy pressure. However, since the totM mass of baryonic matter can be much lower than that of WD at Chandrasekhar mass limit, the peak luminosity should be much dimmer than what we expect before, which may throw a slight shadow on the standard candle of SN Ia in the research of cosmology.

Statistical analyses for NANOGrav 5-year timing residuals

In pulsar timing, timing residuals are the differences between the observed times of arrival and predictions from the timing model. A comprehensive timing model will produce featureless resid- uals, which are presumably composed of dominating noise and weak physical effects excluded from the timing model （e.g. gravitational waves）. In order to apply optimal statistical methods for detecting weak gravitational wave signals, we need to know the statistical properties of noise components in the residuals. In this paper we utilize a variety of non-parametric statistical tests to analyze the whiteness and Gaussianity of the North American Nanohertz Observatory for Gravitational Waves （NANOGrav） 5- year timing data, which are obtained from Arecibo Observatory and Green Bank Telescope from 2005 to 2010. We find that most of the data are consistent with white noise; many data deviate from Gaussianity at different levels, nevertheless, removing outliers in some pulsars will mitigate the deviations.

Unidirectional Rotary Tendency of a Wave-Driven Rotor

Ocean waves can directly drive WECs （wave energy converters） to perform two types of motion--reciprocating motion and unidirectional rotary motion. In general, the efficiency of a reciprocating WEC is strongly wave-frequency dependent, whereas the efficiency of a rotary WEC can be somewhat wave-frequency independent. To date, a huge majority of WEC technologies under development in industry belong to the reciprocating class, and only a few WEC concepts fall in the unidirectional rotary class. In the present work, a wave-driven rotor for unidirectional rotary motion was proposed and characterized. A numerical tool has been developed for characterization of the rotor＇s unidirectional rotary tendency. The tool included a wave model and a drag force model. Simple circular tubes were used as blades in a basic rotor design. This basic design demonstrated strong potential for unidirectional rotary motion at a proper rotor submersion level and under various wave conditions. Two improved designs were yielded from the basic design. In one improved design, the original circular tubes were replaced with cylindrical shells of semicircular cross section as new blades. In another design, the semicircular shells were further modified to become one-way foldable. The two improvements significantly enhanced the rotors＇ unidirectional rotary tendency in waves, which has been verified by numerical simulation. Broad ranges of wave parameters and the submersion level have been numerically explored on the two improved rotor designs in conjunction with dimensional analysis.

压电智能板的稳定性与可控性分析

从能量角度对粘贴有压电传感层与致动层的智能层板的稳定性与可控性作了理论分析.导出了反映智能板能量变化与外加控制电压之间关系的功率流的表达式,并在此基础上,得到了几个有关智能板控制系统稳定性的性质.分析了用整块致动层并施加均布电压来对板进行控制时矩形板的几种不可控情况,并讨论了压电致动层的分块对板可控性的改进作用.

Cotton GhBAK1 Mediates Verticillium Wilt Resistance and Cell Death

Virus-induced gene silencing （VIGS） offers a powerful approach for functional analysis of individual genes by knocking down their expression. We have adopted this approach to dissect gene functions in cotton resistant to Verticfllium wilt, one of the most devastating diseases worldwide. We showed here that highly efficient VIGS was obtained in a cotton breeding line （CA4002） with partial resistance to Verticillium wilt, and GhMKK2 and Gh Ve I are required for its resistance to Verticillium wilt. Arabidopsis AtBAK1/SERK3, a central regulator in plant disease resistance, belongs to a subfamily of somatic embryogenesis receptor kinases （SERKs） with five members, AtSERK1 to AtSERK5. Two BAK1 orthologs and one SERK1 ortholog were identified in the cotton genome. Importantly, GhBAK1 is required for CA4002 resistance to Verticillium wilt. Surprisingly, silencing of GhBAK1 is sufficient to trigger cell death accompanied with production of reactive oxygen species in cotton. This result is distinct from Arabidopsis in which AtBAK1 and AtSERK4 play redundant functions in cell death control. Apparently, cotton has only evolved SERK1 and BAK1 whereas AtSERK4/5 are newly evolved genes in Arabidopsis. Our studies indicate the functional importance of BAK1 in Verticillium wilt resistance and suggest the dynamic evolution of SERK family members in different plant species.