On Cr−C^r-closing for flows on 2-manifolds

For some full measure subset B of the set of iet's (i.e. interval exchange transformations) the following is satisfied: Let X be a $C^r$, $1\le r\le \infty$, vector field, with finitely many singularities, on a compact orientable surface M. Given a nontrivial recurrent point $p\in M$ of X, the holonomy map around p is semi-conjugate to an iet $E :[0,1) \to [0,1).$ If $E\in B$ then there exists a $C^r$ vector field Y, arbitrarily close to X, in the $C^r-$topology, such that Y has a closed trajectory passing through p.Comment: 7 pages, 1 figur

A control system analysis of the dynamic response of N-methyl-D-aspartate glutamate receptors to alcoholism and alcohol withdrawal

Background: N-methyl-D-Aspartate (NMDA) and its receptors (NMDAR) play a critical role in glutamatergic neurotransmission. Ethanol molecules inhibit these receptors, and if the brain is exposed to ethanol chronically, NMDA-induced glutamatergic changes can result in physical dependence to ethanol in order to sustain normal brain function. In these cases, removal of ethanol from the system results in excitotoxic withdrawal. One compensatory mechanism the brain uses to regulate extracellular glutamate concentration is modulating the number of NMDARs at the synapse. Previous work has shown that the number of functional NMDARs at the synapse can be changed by three mechanisms: additional receptors can be synthesized and inserted, receptors can be recruited to the synapse from extrasynaptic regions, or the functionality of existing receptors can be modified. Methods: In this study, we consider the dynamic relocation control of NMDARs in response to chronic alcoholism and withdrawal. Specifically, we (1) propose and construct a mathematical model of the relocation control as a negative feedback system with an explicit set point, (2) investigate the effect of various ethanol consumption and withdrawal profiles on the NMDAR population, and (3) propose and calculate quantitative measures for the extent of withdrawal based on modeled NMDAR populations. Results: A relocation-only model with an explicit set point was developed. The model was shown to apply across a wide range of controller parameters. The results suggest that withdrawal severity does not depend upon the dynamics involved in the development of dependence, and that regulating the blood alcohol level throughout the progression of withdrawal can minimize excitotoxic withdrawal symptoms. Conclusions: The negative feedback control system produced characteristic behaviors of NMDAR populations in response to simulations of alcohol dependence and abrupt withdrawal. The model can also predict the severity of excitotoxic withdrawal following various alcohol consumption and/or withdrawal patterns in order to generate testable hypotheses regarding ameliorating withdrawal

Cross talk between adipose tissue and placenta in obese and gestational diabetes mellitus pregnancies via exosomes

Obesity is an important public health issue worldwide, where it is commonly associated with the development of metabolic disorders, especially insulin resistance (IR). Maternal obesity is associated with an increased risk of pregnancy complications, especially gestational diabetes mellitus (GDM). Metabolism is a vital process for energy production and the maintenance of essential cellular functions. Excess energy storage is predominantly regulated by the adipose tissue. Primarily made up of adipocytes, adipose tissue acts as the body’s major energy reservoir. The role of adipose tissue, however, is not restricted to a “bag of fat.” The adipose tissue is an endocrine organ, secreting various adipokines, enzymes, growth factors, and hormones that take part in glucose and lipid metabolism. In obesity, the greater portion of the adipose tissue comprises fat, and there is increased pro-inflammatory cytokine secretion, macrophage infiltration, and reduced insulin sensitivity. Obesity contributes to systemic IR and its associated metabolic complications. Similar to adipose tissue, the placenta is also an endocrine organ. During pregnancy, the placenta secretes various molecules to maintain pregnancy physiology. In addition, the placenta plays an important role in metabolism and exchange of nutrients between mother and fetus. Inflammation at the placenta may contribute to the severity of maternal IR and her likelihood of developing GDM and may also mediate the adverse consequences of obesity and GDM on the fetus. Interestingly, studies on maternal insulin sensitivity and secretion of placental hormones have not shown a positive correlation between these phenomena. Recently, a great interest in the field of extracellular vesicles (EVs) has been observed in the literature. EVs are produced by a wide range of cells and are present in all biological fluids. EVs are involved in cell-to-cell communication. Recent evidence points to an association between adipose tissue-derived EVs and metabolic syndrome in obesity. In this review, we will discuss the changes in human placenta and adipose tissue in GDM and obesity and summarize the findings regarding the role of adipose tissue and placenta-derived EVs, with an emphasis on exosomes in obesity, and the contribution of obesity to the development of GDM

SELECTION FOR YIELD AT TWO FERTILIZER LEVELS IN SMALL-SEEDED COMMON BEAN

Selection for seed yield (visual in the F2, visual and pl:t yield from the F3 to F5, and yield tests in F6) was carried out in two crosses of common bean (Phaseolus vulgaris L.) in high and low soil fertility environments at ClAT-Quilichao, Colombia. Parents were small-seeded and tolerant to low soil phosphorus, possessed indeterminate bush growth habit, and belonged to lowland tropical gene pools of Middle America. The mean yield of selected lines from low (LFS) and high (HFS) soil fertility environments was significantly higher than the mean of the parents in both crosses when tested in high fertility (HF) but not in low fertility (LF). The highest yielding LFS and HFS lines from A 286 x (G 5059 x A 80) and the LFS line from A 286 x ICA Pijao outyielded the best check cultivar, Carioca, in HF. No line yielded significantly more than A 286, the best parent used in both crosses. The mean effect of fertilizer levels on selection for seed yield was nonsignificant. Lines selected under two environments showed similar but average response and high stability of performance under variable environments. Low soil fertility accelerated maturity and reduced 100-seed weight and seed yield\u2

Performance of small-seeded common bean from the second selection cycle and multiple-cross intra- and interracial populations

Twenty experimental lines of small-seeded common^bean (Phaseolus vulgaris L.) of Middle American origin from the second cycle of selection (SCS) in multiple cross intra- and interracial populations were evaluated with two control cultivars from the first cycle of selection (FCS) derived from single-cross intraracial populations and three standard controls at three locations for 3 yr (1988-1990) in Colombia. A 5 x 5 lattice design with four replications was used. Each plot consisted of four rows, 5 m long in the first year and 7 m long in the next 2 years. To develop experimental lines in both selection cycles, visual mass selection for seed yield and/or resistance tb diseases in individual plants and plant-to-progeny rows was practiced in early generations. The F2 and F3 were managed by the single-pod bulk method followed by the single plant harvests (F4 or F5), progeny tests (F5 or F6), and seed increases (F6 or F7). The F4- or F5-derived lines were tested for seed yield in F7 or F8. Thirteen lines from the SCS outyielded both control cultivars from the FCS and one standard control. However, only two lines, A 785 and A774, from the SCS outyielded the best standard control, cultivar Carioca, by an average of 7.77o. Both lines were derived from interracial populations involving high-yielding parents possessing positive general combining ability for seed yield. Most improved lines from the SCS possessed higher yield per day and higher disease resistance. No apparent changes were recorded in days to maturity and 100-seed weight for high-yielding lines. Late-maturing lines usually had lower yield and yield per day

SELECTION FOR YIELD AT TWO FERTILIZER LEVELS IN SMALL-SEEDED COMMON BEAN

Selection for seed yield (visual in the F2, visual and pl:t yield from the F3 to F5, and yield tests in F6) was carried out in two crosses of common bean (Phaseolus vulgaris L.) in high and low soil fertility environments at ClAT-Quilichao, Colombia. Parents were small-seeded and tolerant to low soil phosphorus, possessed indeterminate bush growth habit, and belonged to lowland tropical gene pools of Middle America. The mean yield of selected lines from low (LFS) and high (HFS) soil fertility environments was significantly higher than the mean of the parents in both crosses when tested in high fertility (HF) but not in low fertility (LF). The highest yielding LFS and HFS lines from A 286 x (G 5059 x A 80) and the LFS line from A 286 x ICA Pijao outyielded the best check cultivar, Carioca, in HF. No line yielded significantly more than A 286, the best parent used in both crosses. The mean effect of fertilizer levels on selection for seed yield was nonsignificant. Lines selected under two environments showed similar but average response and high stability of performance under variable environments. Low soil fertility accelerated maturity and reduced 100-seed weight and seed yield\u2

Use of interracial hybridization in breeding the race Durango common bean

Recently, interracial hybridization was used successfully in breeding common bean (Phaseolus vulgaris L.), but its use has not been adequately documented. Approximately 125 lines with medium-sized seed were selected in the first cycle, mostly from race Durango x race Mesoamerica (both from the Middle American domestication center) single- and multiple-cross populations, for disease resistance and race Durango characteristics. Fifteen of these improved lines, three race Durango control cultivars, and one control cultivar each from races Jalisco and Mesoamerica were evaluated for 3 yr (1989-1991) at three locations in Colombia. A randomized complete block design with three replications was used. Lines were developed using visual mass selection for seed yield and/or resistance to diseases in F2 and F3, followed by single plant harvests in F4 or F5 and seed increases in F6 or F7. Lines resistant to bean common mosaic virus and possessing other desirable traits were yield-tested in F7 or F8. All but two lines outyielded Alteho and Flor de Mayo, the highest yielding control cultivars from races Durango and Jalisco, respectively. Two lines also outyielded Carioca, the race Mesoamerica control cultivar. Improved lines tended to possess higher yield per day. All lines were resistant to bean common mosaic virus and most lines also carried a high level of resistance to anthracnose. Plant, seed, and maturity characteristics of most improved lines were similar to those of race Durango control cultivars. These results support the use of interracial hybridization in improving race Durango common bean

SELECTION FOR YIELD AT TWO FERTILIZER LEVELS IN SMALL-SEEDED COMMON BEAN

Selection for seed yield (visual in the F2, visual and pl:t yield from the F3 to F5, and yield tests in F6) was carried out in two crosses of common bean (Phaseolus vulgaris L.) in high and low soil fertility environments at ClAT-Quilichao, Colombia. Parents were small-seeded and tolerant to low soil phosphorus, possessed indeterminate bush growth habit, and belonged to lowland tropical gene pools of Middle America. The mean yield of selected lines from low (LFS) and high (HFS) soil fertility environments was significantly higher than the mean of the parents in both crosses when tested in high fertility (HF) but not in low fertility (LF). The highest yielding LFS and HFS lines from A 286 x (G 5059 x A 80) and the LFS line from A 286 x ICA Pijao outyielded the best check cultivar, Carioca, in HF. No line yielded significantly more than A 286, the best parent used in both crosses. The mean effect of fertilizer levels on selection for seed yield was nonsignificant. Lines selected under two environments showed similar but average response and high stability of performance under variable environments. Low soil fertility accelerated maturity and reduced 100-seed weight and seed yield\u2

Modelling and Analysis of Nonstationary Vehicle-to-Infrastructure Channels with Time-Variant Angles of Arrival

In mobile radio channel modelling, it is generally assumed that the angles of arrival (AOAs) are independent of time. This assumption does not in general agree with real-world channels in which the AOAs vary with the position of a moving receiver. In this paper, we first present a mathematical model for the time-variant AOAs. This model serves as the basis for the development of two nonstationary multipath fading channels models for vehicle-to-infrastructure communications. The statistical properties of both channel models are analysed with emphasis on the time-dependent autocorrelation function (ACF), time-dependent mean Doppler shift, time-dependent Doppler spread, and the Wigner-Ville spectrum. It is shown that these characteristic quantities are greatly influenced by time-variant AOAs. The presented analytical framework provides a new view on the channel characteristics that goes well beyond ultra-short observation intervals over which the channel can be considered as wide-sense stationary