A novel rate-dependent cohesive-zone model combining damage and visco-elasticity

This is the author’s post-print version of a work that was accepted for publication in Computers & Structures. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication.The published paper is available from the link below.This paper presents a novel rate-dependent cohesive-zone model combining damage and visco-elasticity and based on two fundamental assumptions. Firstly we postulate the existence of an intrinsic (i.e. rate-independent) fracture energy. Secondly, within a thermodynamically consistent damage-mechanics framework we assume that the evolution of the damage variable is related to the current free energy and to the intrinsic fracture energy. The underlying idea is that the energy of the bonds at the micro-level is rate-independent and that the rate-dependence of the overall dissipated energy during crack propagation is a natural by-product of the visco-elastic dissipation lumped on the zero-thickness interface. Quite good agreement within an expected range of loading rates was obtained between numerical and experimental results for a DCB specimen with steel arms bonded through a rubber interface. This is despite the fact that for this application the model has been kept as simple as possible using a quadratic elastic energy and linear visco-elasticity with one relaxation time only. Therefore, the presented results support the fundamental principles behind the proposed approach and indicate that the model has the potential to be refined into a highly accurate tool of analysis based on sound physical arguments.EPSR

Correlation between Exit Examination of Writing Proficiency Results and Freshman English grades in Washington State Distance Learning Students

The purpose of this study was to determine if there was a relationship between Washington State undergraduate students\u27 freshman English composition grade and their success on Old Dominion University\u27s Exit Examination of Writing Proficiency

Evidence on the Efficacy of School-Based Incentives for Healthy Living

We analyze the effects of a school-based incentive program on children's exercise habits. The program offers children an opportunity to win prizes if they walk or bike to school during prize periods. We use daily child-level data and individual fixed effects models to measure the impact of the prizes by comparing behavior during prize periods with behavior during non-prize periods. Variation in the timing of prize periods across different schools allows us to estimate models with calendardate fixed effects to control for day-specific attributes, such as weather and proximity to holidays. On average, we find that being in a prize period increases riding behavior by sixteen percent, a large impact given that the prize value is just six cents per participating student. We also find that winning a prize lottery has a positive impact on ridership over subsequent weeks; consider heterogeneity across prize type, gender, age, and calendar month; and explore differential effects on the intensive versus extensive margins.health; exercise; children; school; incentives; active commuting

On Interferometric Duality in Multibeam Experiments

We critically analyze the problem of formulating duality between fringe visibility and which-way information, in multibeam interference experiments. We show that the traditional notion of visibility is incompatible with any intuitive idea of complementarity, but for the two-beam case. We derive a number of new inequalities, not present in the two-beam case, one of them coinciding with a recently proposed multibeam generalization of the inequality found by Greenberger and YaSin. We show, by an explicit procedure of optimization in a three-beam case, that suggested generalizations of Englert's inequality, do not convey, differently from the two-beam case, the idea of complementarity, according to which an increase of visibility is at the cost of a loss in path information, and viceversa.Comment: 26 pages, 1 figure, substantial changes in the text, new material has been added in Section 3. Version to appear in J.Phys.

Gentling and welfare of lambs

In traditional sheep production systems, lambs are suckled by their mothers and then gradually weaned at 35 days of age. However, the increased size of intensive dairy sheep flocks to obtain greater amounts of ovine milk for cheese making, is promoting the diffusion of artificial rearing programs involving early separation of lambs from their mothers. Maternal deprivation soon after birth can have detrimental effects on lamb immune functions, and lead to altered cortisol secretion and behavioural responses to isolation (Napolitano et al., 1995). Human-animal interactions have been documented to play a role in sustaining the welfare and production of domestic animals (Hemsworth, 2003). In addition, gentled animals are less difficult to be handled and less susceptible to the stress induced by management practices involving human contacts (Lensink et al., 2000). The aim of the present trial was to investigate the effects of gently handling newborn lambs on their behavioural, immune and endocrine responses, and on their growth rate when mothered or artificially reared

Polyether from a biobased Janus molecule as surfactant for carbon nanotubes

A new polyether (PE) was prepared from a biobased Janus molecule, 2-(2,5-dimethyl-1H-pyrrol-1-yl)-1,3- propanediol (serinol pyrrole, SP). SP was synthesized with very high yield (about 96%) and high atom efficiency (about 80%) by reacting a biosourced molecule, such as serinol, with 2,5-hexanedione in the absence of solvent or catalyst. The reaction of SP with 1,6-dibromohexane led to PE oligomers, that were used as surfactants for multiwalled carbon nanotubes (MWCNT), in ecofriendly polar solvents such as acetone and ethyl acetate. The synergic interaction of aromatic rings and oxyalkylene sequences with the carbon allotrope led to dramatic improvement of surfactant efficiency: only 24% of SP based PE was extracted with ethyl acetate from the adduct with MWCNT, versus 98% of a typical pluronic surfactant. Suspensions of MWCNT-PE adducts in ethyl acetate were stable for months. High resolution transmission electron microscopy revealed a film of oligomers tightly adhered to MWCNT surface

Standardised surface electromyography allows effective submental muscles assessment

The aims of this pilot study were to evaluate: (i) the reproducibility and variability of an electromyographical protocol developed for the assessment of submental muscles (SM) (ii) to apply the new protocol to maximal teeth clenching, a simple and largely studied static task in order to quantify the relative contribution of submental muscles. In 20 healthy subjects, aged 19-35years, surface electromyography of SM, masseter (MM) and anterior temporalis (TA) muscles was performed during maximal voluntary clenching (MVC) with and without cotton rolls and the pushing of the tongue against the palate. Clenching on cotton rolls and pushing the tongue against the palate were used to standardise respectively MM and TA, and SM muscular potentials. The exercises were repeated in two appointments (T1-T2); submental muscles standardisation was also repeated twice (A-B) in each session to assess repeatability. Symmetry and activity were calculated for each couple of muscles. A two-way analysis of variance was computed for SM: no Factor 1 (T1 vs T2) or Factor 2 (A vs B) or F1 7F2 significant effects were found. SM recruitment was 31% of the maximal activity, with symmetry values larger than 80%. In conclusion, standardised electromyography allows a reliable assessment of Submental muscles activity

Effects of gentling on behavior and meat quality of lambs

Within few hours after parturition lambs develop a strong and selective relationship with their mothers (Poindron and Le Neindre, 1980). In order to increase the amount of milk available for transformation, lambs often are prematurely separated from the ewes, thus inducing an early disruption of the mother-young relationship. A number of authors demonstrated that the lack of the maternal bond can inhibit the welfare state of the lambs (Sevi et al., 2001) and reduced animal welfare can have detrimental effects on meat quality in many animals species (Gregory, 1998) as well as in sheep (Napolitano et al., 2002a). A possible recover from conditions of poor animal welfare may be attained through the administration of gentle contacts by humans (Boivin et al., 2000) which may supply an additional social bond with members of a different animal species. The present study aims to verify the effect of artificial rearing on lamb welfare and meat quality, and assess the possibility to increase both by means of gentling

In Pursuit of Good & Gold: Data Observations of Employee Ownership & Impact Investment

A startup\u27s path to self-sustaining profitability is risky and hard, and most do not make it. Venture capital (VC) investors try to improve these odds with contractual terms that focus and sharpen employees\u27 incentives to pursue gold. If the employees and investors expect the startup to balance the goal of profitability with another goal - the goal of good - the risks are likely to both grow and multiply. They grow to the extent that profits are threatened, and they multiply to the extent that balancing competing goals adds a dimension to the incentive problem. In this Article, we explore contracting terms specific to impact investing funds and their portfolio companies. We observe one possible private ordering mechanism to balance and align interests to serve both goals: employee ownership. Traditional VC investments confront contracting challenges as the portfolio companies and investors balance their interests, which may not align. The VC contracting literature identifies several agency costs that contractual terms can address. Contracts can help attract the right employees, then encourage them to work, stay, and share their best ideas. But, the existing literature addresses traditional agency costs with respect to the pursuit of a single monetary goal. Impact investment funds that balance monetary goals, short-term or long, with other goals may strike a different balance in negotiating with companies. We examine how the introduction of new motivations and interests into a precarious negotiation process shapes contracting outcomes. We address this question empirically by analyzing the role of employee stock ownership in impact investment fund contracts when investing in targeted portfolio companies. That a startup\u27s employees might receive shares and options is uncontroversial. Indeed, this appears in many ways to be fundamental to today\u27s startup culture. Might impact investors mandate that employees own shares as a means to balance dual goals? That is the key question for our analysis

Leaning for the Tape: Evidence of Gaming Behavior in Equity Mutual Funds

We present evidence that fund managers inflate quarter-end portfolio prices with last-minute purchases of stocks already held. The magnitude of price inflation ranges from 0.5 percent per year for large-cap funds to well over 2 percent for small-cap funds. We find that the cross section of inflation matches the cross section of incentives from the flow/performance relation, that a surge of trading in the quarter\u27s last minutes coincides with a surge in equity prices, and that the inflation is greatest for the stocks held by funds with the most incentive to inflate, controlling for the stocks\u27 size and performance