Homoclinic Orbits in Several Classes of Three-Dimensional Piecewise Affine Systems with Two Switching Planes

The existence of homoclinic orbits or heteroclinic cycle plays a crucial role in chaos research. This paper investigates the existence of the homoclinic orbits to a saddle-focus equilibrium point in several classes of three-dimensional piecewise affine systems with two switching planes regardless of the symmetry. An analytic proof is provided using the concrete expression forms of the analytic solution, stable manifold, and unstable manifold. Meanwhile, a sufficient condition for the existence of two homoclinic orbits is also obtained. Furthermore, two concrete piecewise affine asymmetric systems with two homoclinic orbits have been constructed successfully, demonstrating the method’s effectiveness.

Alcohol Abuse and Insomnia Disorder: Focus on a Group of Night and Day Workers

The sleep-wake cycle plays a fundamental role in maintaining the physiological balance of our body. Its alteration favours the genesis of several organic alterations and diseases including sleep disorders and the consumption of several substances of abuse. It has been reported that the work activity, especially that carried out during the night, is able to influence the sleep-wake cycle, promoting the development of insomnia, which, in turn, would subject the worker to a stressful condition such as to encourage adverse behaviour such as the use/abuse of psychotropic substances. Based on the above premises, the aim of our research was to evaluate, in night workers: (i) the pattern of consumption of alcoholic beverages; (ii) the presence of insomnia; and (iii) the possible correlation between alcohol consumption and insomnia disorder. We used the AUDIT-C test (the abbreviated version of the Alcohol Use Disorders Identification Test) and the Insomnia Severity Index to assess alcohol consumption and insomnia disorder, respectively. All questionnaires were completed by workers of both sexes belonging to different types of work activities, exclusively day or night. The results of our research show a higher propensity of night workers to consume alcoholic beverages than those who work during daytime hours, often in binge-drinking mode. In addition, an increase in the amount of alcohol consumed was found to be related to insomnia disorder, especially in night workers. This study provides further awareness of the importance of the negative impact of alcohol consumption on sleep quality in night workers.

Social process in a voluntary organisation: a study of adult membership in the Scout Association of New Zealand

<p>This thesis examines social processes in a large, voluntary organisation. The investigation was concerned with the activities and retention of lower-level adult members in the Scout Association of New Zealand. The demographic, socio-economic and organisational background of members, their attitudes, and the organisational context within which activity occurs were examined with reference to the relationship of these variables with the satisfaction, commitment and participation of members. Particular attention was given to five organisational variables: size, communication, control, support and effectiveness. Attitudinal variables such as solidarity, ideology, prestige and orientation were also examined. It was found that the organisational variables were most clearly related to differences in satisfaction, commitment and participation. This was described firstly in terms of an association between larger size, better and more frequent communication, and higher levels of control, support, and effectiveness. The latter in turn was related to higher levels of satisfaction, commitment, and participation. Background variables, particularly age, also proved important. This suggested that the life cycle plays a part in voluntary association membership and activity. It was concluded that the main organisational variables are affected by the peripheral structural position of voluntary associations in New Zealand society. The sanctions available to senior officials are few and generally weak, and there is often little pressure to pursue some of the more intangible formal goals. Adherence to official procedures varies, with frequent blockages of control, communication and support. This results in considerable differences in the organisational environment within which members operate. The study was carried out over two years. Observation, semi-structured and unstructured interviews were used, as well as a lengthy questionnaire.</p>

The Open Polar Cap of Rotating Magnetospheres

&lt;p&gt;The classic Dungey cycle plays an essential role in understanding the dynamics of the terrestrial magnetosphere. However, its direct applicability to planetary magnetospheres such as Jupiter is limited, especially when the planetary rotation is much faster than the Earth. We use a series of numerical experiments to show the transition of the terrestrial magnetosphere from a classic Dungey cycle, convection-dominated system to rotation-dominated configurations. The numerical experiments use the Earth's magnetosphere-ionosphere system as a testbed, with modified rotation speed to increase the influence of planetary rotation over solar wind driving, characterized by the ratio between the solar wind merging potential and the polar cap rotation potential. Results show that when the rotation potential of the polar magnetosphere becomes comparable to the merging potential of the solar wind, the classic Dungey cycle is modified by azimuthal transport of magnetic flux, resulting in a more closed polar magnetosphere with a crescent-shaped open flux region in the ionosphere. These numerical experiments provide a theoretical framework for understanding the fundamentals of magnetospheric physics, which is potentially applicable to the Saturn, Jupiter, and exo-planetary systems.&lt;/p&gt;

Silicon Isotope Signatures of Radiolaria Reveal Taxon-Specific Differences in Isotope Fractionation

The global silicon (Si) cycle plays a critical role in regulating the biological pump and the carbon cycle in the oceans. A promising tool to reconstruct past dissolved silicic acid (DSi) concentrations is the silicon isotope signature of radiolaria (δ30Sirad), siliceous zooplankton that dwells at subsurface and intermediate water depths. However, to date, only a few studies on sediment δ30Sirad records are available. To investigate its applicability as a paleo proxy, we compare the δ30Sirad of different radiolarian taxa and mixed radiolarian samples from surface sediments off Peru to the DSi distribution and its δ30Si signatures (δ30SiDSi) along the coast between the equator and 15°S. Three different radiolarian taxa were selected according to their specific habitat depths of 0–50 m (Acrosphaera murrayana), 50–100 m (Dictyocoryne profunda/truncatum), and 200–400 m (Stylochlamydium venustum). Additionally, samples containing a mix of species from the bulk assemblage covering habitat depths of 0 to 400 m have been analyzed for comparison. We find distinct δ30Sirad mean values of +0.70 ± 0.17‰ (Acro; 2 SD), +1.61 ± 0.20 ‰ (Dictyo), +1.19 ± 0.31 ‰ (Stylo) and +1.04 ± 0.19 ‰ (mixed radiolaria). The δ30Si values of all individual taxa and the mixed radiolarian samples indicate a significant (p &lt; 0.05) inverse relationship with DSi concentrations of their corresponding habitat depths. However, only δ30Si of A. murrayana are correlated to DSi concentrations under normally prevailing upwelling conditions. The δ30Si of Dictyocoryne sp., Stylochlamydium sp., and mixed radiolaria are significantly correlated to the lower DSi concentrations either associated with nutrient depletion or shallower habitat depths. Furthermore, we calculated the apparent Si isotope fractionation between radiolaria and DSi (Δ30Si ∼ 30ε = δ 30Sirad − δ 30SiDSi) and obtained values of −1.18 ± 0.17 ‰ (Acro), −0.05 ± 0.25 ‰ (Dictyo), −0.34 ± 0.27 ‰ (Stylo), and −0.62 ± 0.26 ‰ (mixed radiolaria). The significant differences in Δ30Si between the order of Nassellaria (A. murrayana) and Spumellaria (Dictyocoryne sp. and Stylochlamydium sp.) may be explained by order-specific Si isotope fractionation during DSi uptake, similar to species-specific fractionation observed for diatoms. Overall, our study provides information on the taxon-specific fractionation factor between radiolaria and seawater and highlights the importance of taxonomic identification and separation to interpret down-core records.

Positioning of Apple’s Growth Cycle Based on Pattern Recognition

The positioning of the apple growth cycle plays a very important role in predicting the development of apples and guiding fruit farmers in agricultural operations. The traditional method of manually positioning the apple growth cycle has problems such as low efficiency and poor accuracy. Pattern recognition provides support for continuous and rapid positioning during the apple growth process. Under the natural conditions of the orchard, due to the large differences in the individual colors of the apples during the growth process and the influence of factors such as light changes, the photographed apple images are more complex, which brings certain difficulties to the segmentation and recognition of the apples. In this paper, pattern recognition is used to automatically identify and extract the growth stages of apples, a hue intensity (HI) color segmentation algorithm based on a Gaussian distribution model based on prior knowledge is studied, and then an active shape model (ASM) is used to identify each period of apple growth based on pattern recognition. After a series of experimental verifications, the ASM-based automatic identification method proposed in this paper is feasible and can identify the various growth periods of apples, thereby serving the mechanized production of apples.

Laboratory Culture-Based Characterization of the Resting Stage Cells of the Brown-Tide-Causing Pelagophyte, Aureococcus anophagefferens

Life history (life cycle) plays a vital role in the ecology of some microalgae; however, the well-known brown-tide-causing pelagophyte Aureococcus anophagefferens has been barely investigated in this regard. Recently, based mainly on detections in marine sediments from China, we proved that this organism has a resting stage. We, therefore, conducted a follow-up study to characterize the resting stage cells (RSCs) of A. anophagefferens using the culture CCMP1984. The RSCs were spherical, larger than the vegetative cells, and smooth in cell surface and contained more aggregated plastid but more vacuolar space than vegetative cells. RSCs contained a conspicuous lipid-enriched red droplet. We found a 9.9-fold decrease in adenosine triphosphate (ATP) content from vegetative cells to RSCs, indicative of a "resting" or dormant physiological state. The RSCs stored for 3 months (at 4 °C in darkness) readily reverted back to vegetative growth within 20 days after being transferred to the conditions for routine culture maintenance. Our results indicate that the RSCs of A. anophagefferens are a dormant state that differs from vegetative cells morphologically and physiologically, and that RSCs likely enable the species to survive unfavorable conditions, seed annual blooms, and facilitate its cosmopolitan distribution that we recently documented.

Oxaloacetate Mediates Mitochondrial Metabolism and Function

Oxaloacetate, an intermediate in the tricarboxylic acid cycle, plays important roles in regulating mitochondrial function, gluconeogenesis, the urea cycle, and amino acid syntheses. Because this compound is not stable, more information is needed about its stability profile before its medicinal potential can be realized. In this short review, we present current knowledge and understanding of oxaloacetate with a focus on its stability, degradation, quantification methods, regulation of mitochondrial function, and potential therapeutic benefits. Further, we report previously unpublished spectral data related to the stability profile of oxaloacetate. We found that oxaloacetate has a half-life of about 14 hours in biological aqueous solution at 25&#176;C before degrading into pyruvate. This mandates careful attention to handling this compound including storage at -20 to -80&#176;C when not in use to prolong its shelf-life. Also, the oxaloacetate stability profile needs to be taken into account when conducting experiments involving the compound either in clinical trials or evaluating it as a health supplement or for other experiments. Measuring oxaloacetate by mass-spectrometry requires cumbersome derivatization to assure stability. However, we found that NMR can be used to detect oxaloacetate quantitatively without the need for making derivatives, and the NMR method is sensitive enough to detect oxaloacetate in the micromolar range. Using this method, we showed that oxaloacetate regulates mitochondrial complex II-driven respiration by potent inhibition of succinate dehydrogenase. Moreover, a growing literature in the past few years suggests that oxaloacetate may have therapeutic benefits in treating a variety of diseases.

Impact of Design Patterns on Software Complexity and Size

Many different factors influence the quality of software. Among the most important of these factors is software complexity. One way to improve software quality, therefore, is to minimize its complexity making it more understandable and maintainable. The design phase of the software development life cycle plays an instrumental role in fostering quality in software. Seasoned designers often use past design best practices codified in the form of design patterns to make their designs and the resultant code more elegant, robust, and resilient to change. Little work, however, has been done to empirically assess the quantitative impact of design patterns on software complexity. This research is an attempt to fill this gap. A comparative analysis of before and after versions of program pairs written without and with design patterns was performed for all twenty three GoF (Gang of Four) design patterns. These program pairs were collected (or, in some cases, developed) and compared with respect to their complexity and size. The results of this comparative analysis reveal that the cyclomatic complexity of the programs written using design patterns was less for most of the design patterns as compared to the programs written without using design patterns. However, the values of CK metrics, number of classes, and software size SLOC (Source Lines of Code) increased when design patterns were used.