Wave localization in strongly nonlinear Hertzian chains with mass defect

We investigate the dynamical response of a mass defect in a one-dimensional non-loaded horizontal chain of identical spheres which interact via the nonlinear Hertz potential. Our experiments show that the interaction of a solitary wave with a light intruder excites localized mode. In agreement with dimensional analysis, we find that the frequency of localized oscillations exceeds the incident wave frequency spectrum and nonlinearly depends on the size of the intruder and on the incident wave strength. The absence of tensile stress between grains allows some gaps to open, which in turn induce a significant enhancement of the oscillations amplitude. We performed numerical simulations that precisely describe our observations without any adjusting parameters.Comment: 4 pages, 5 figures, submitted for publicatio

Determinants of Smallholder African Indigenous Leafy Vegetables Farmers’ Market Participation Behaviour in Nyamira County, Kenya

Participation in commercial agriculture holds key prospects for unravelling pertinent opportunities necessary for providing better incomes and sustainable livelihoods for small-scale farmers. Therefore, market participation has the potential to increase farmers’ rural incomes and employment opportunities, especially if farmers concentrate on production and marketing of indigenous crops requiring low inputs such as African indigenous leafy vegetables (AILV). This study examined factors that influenced smallholders’ market participation behaviour. Data was obtained through a household survey using structured questionnaires administered to 254 respondents picked for the study through a multistage sampling procedure. An ordered probit model was used to determine factors influencing smallholders’ market participation as either net buyers, net sellers or autarchies. Findings revealed that marketing experience, land ownership, households’ food self-sufficiency, contractual marketing, access to credit and extension services significantly influenced the regimes in which smallholders participated in markets. It is not enough that farmers merely participated in markets, rather they should participate in markets profitably as net sellers. Identifying the specific challenges and requirements that are unique for each market regime (net sellers, autarkic and net buyers) through proper targeting and screening of farmers is necessary. Here, equipping extension workers with the ability to address the specific needs of each group is recommended. Further, the study advocates for group marketing to increase farmers’ bargaining power during negotiations, in addition to reducing transportation costs by transporting produce in groups. Improving the state of the roads linking producers to markets is also important in reducing the cost of transporting produce, as well as the cost of searching for markets. Keywords: Autarkic, Net buyer, Net seller, Ordered Probit, Smallholder, Nyamira, Keny

The promise of open survey questions - The validation of text-based job satisfaction measures

Recent advances in computer-aided text analysis (CATA) have allowed organizational scientists to construct reliable and convenient measures from open texts. As yet, there is a lack of research into using CATA to analyze responses to open survey questions and constructing text-based measures of psychological constructs. In our study, we demonstrated the potential of CATA methods for the construction of text-based job satisfaction measures based on responses to a completely open and semi-open question. To do this, we employed three sentiment analysis techniques: Linguistic Inquiry and Word Count 2015, SentimentR and SentiStrength, and quantified the forms of measurement error they introduced: specific factor error, algorithm error and transient error. We conducted an initial test of the text-based measures’ validity, assessing their convergence with closed-question job satisfaction measures. We adopted a time-lagged survey design (Nwave 1 = 996; Nwave 2 = 116) to test our hypotheses. In line with our hypotheses, we found that specific factor error is higher in the open question text-based measure than in the semi-open question text-based measure. As expected, algorithm error was substantial for both the open and semi-open question text-based measures. Transient error in the text-based measures was higher than expected, as it generally exceeded the transient error in the human-coded and the closed job satisfaction question measures. Our initial test of convergent and discriminant validity indicated that the semi-open question text-based measure is especially suitable for measuring job satisfaction. Our article ends with a discussion of limitations and an agenda for future research

The promise of open survey questions - The validation of text-based job satisfaction measures

Recent advances in computer-aided text analysis (CATA) have allowed organizational scientists to construct reliable and convenient measures from open texts. As yet, there is a lack of research into using CATA to analyze responses to open survey questions and constructing text-based measures of psychological constructs. In our study, we demonstrated the potential of CATA methods for the construction of text-based job satisfaction measures based on responses to a completely open and semi-open question. To do this, we employed three sentiment analysis techniques: Linguistic Inquiry and Word Count 2015, SentimentR and SentiStrength, and quantified the forms of measurement error they introduced: specific factor error, algorithm error and transient error. We conducted an initial test of the textbased measures' validity, assessing their convergence with closed-question job satisfaction measures. We adopted a time-lagged survey design (Nwave 1 = 996; Nwave 2 = 116) to test our hypotheses. In line with our hypotheses, we found that specific factor error is higher in the open question text-based measure than in the semi-open question text-based measure. As expected, algorithm error was substantial for both the open and semi-open question textbased measures. Transient error in the text-based measures was higher than expected, as it generally exceeded the transient error in the human-coded and the closed job satisfaction question measures. Our initial test of convergent and discriminant validity indicated that the semi-open question text-based measure is especially suitable for measuring job satisfaction. Our article ends with a discussion of limitations and an agenda for future research

Economic analysis of fertilizer options for maize production in Tanzania

United States Agency for International Developmen

High frequency burst firing of granule cells ensures transmission at the parallel fiber to purkinje cell synapse at the cost of temporal coding.

Cerebellar granule cells (GrCs) convey information from mossy fibers (MFs) to Purkinje cells (PCs) via their parallel fibers (PFs). MF to GrC signaling allows transmission of frequencies up to 1 kHz and GrCs themselves can also fire bursts of action potentials with instantaneous frequencies up to 1 kHz. So far, in the scientific literature no evidence has been shown that these high-frequency bursts also exist in awake, behaving animals. More so, it remains to be shown whether such high-frequency bursts can transmit temporally coded information from MFs to PCs and/or whether these patterns of activity contribute to the spatiotemporal filtering properties of the GrC layer. Here, we show that, upon sensory stimulation in both un-anesthetized rabbits and mice, GrCs can show bursts that consist of tens of spikes at instantaneous frequencies over 800 Hz. In vitro recordings from individual GrC-PC pairs following high-frequency stimulation revealed an overall low initial release probability of ~0.17. Nevertheless, high-frequency burst activity induced a short-lived facilitation to ensure signaling within the first few spikes, which was rapidly followed by a reduction in transmitter release. The facilitation rate among individual GrC-PC pairs was heterogeneously distributed and could be classified as either "reluctant" or "responsive" according to their release characteristics. Despite the variety of efficacy at individual connections, grouped activity in GrCs resulted in a linear relationship between PC response and PF burst duration at frequencies up to 300 Hz allowing rate coding to persist at the network level. Together, these findings support the hypothesis that the cerebellar granular layer acts as a spatiotemporal filter between MF input and PC output (D'Angelo and De Zeeuw, 2009)

The Role of Amygdala in Self-Conscious Emotions in a Patient With Acquired Bilateral Damage

Shame plays a fundamental role in the regulation of our social behavior. One intriguing question is whether amygdala might play a role in processing this emotion. In the present single-case study, we tested a patient with acquired damage of bilateral amygdalae and surrounding areas as well as healthy controls on shame processing and other social cognitive tasks. Results revealed that the patient\u2019s subjective experience of shame, but not of guilt, was more reduced than in controls, only when social standards were violated, while it was not different than controls in case of moral violations. The impairment in discriminating between normal social situations and violations also emerged. Taken together, these findings suggest that the role of the amygdala in processing shame might reflect its relevance in resolving ambiguity and uncertainty, in order to correctly detect social violations and to generate shame feelings

Regional differences in the three-dimensional bone microstructure of the radial head:implications for observed fracture patterns

Introduction: A characterization of the internal bone microstructure of the radial head could provide a better understanding of commonly occurring fracture patterns frequently involving the (antero)lateral quadrant, for which a clear explanation is still lacking. The aim of this study is to describe the radial head bone microstructure using micro-computed tomography (micro-CT) and to relate it to gross morphology, function and possible fracture patterns. Materials and methods: Dry cadaveric human radii were scanned by micro-CT (17 μm/pixel, isotropic). The trabecular bone microstructure was quantified on axial image stacks in four quadrants: the anterolateral (AL), posterolateral (PL), posteromedial (PM) and anteromedial (AM) quadrant. Results: The AL and PL quadrants displayed the significantly lowest bone volume fraction and trabecular number (BV/TV range 12.3–25.1%, Tb.N range 0.73–1.16 mm−1) and highest trabecular separation (Tb.Sp range 0.59–0.82 mm), compared to the PM and AM quadrants (BV/TV range 19.9–36.9%, Tb.N range 0.96–1.61 mm−1, Tb.Sp range 0.45–0.74 mm) (p = 0.03). Conclusions: Our microstructural results suggest that the lateral side is the “weaker side”, exhibiting lower bone volume faction, less trabeculae and higher trabecular separation, compared to the medial side. As the forearm is pronated during most falls, the underlying bone microstructure could explain commonly observed fracture patterns of the radial head, particularly more often involving the AL quadrant. If screw fixation in radial head fractures is considered, surgeons should take advantage of the “stronger” bone microstructure of the medial side of the radial head, should the fracture line allow this

Landscape natural resources management using forage grasses and legume intercrops

United States Agency for International Developmen

Manejo de sistemas de produção de centeio visando a produção de forragem e de sementes para a agricultura familiar.

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