Missing women in STEM occupations: The impact of university education on the gender gap in graduates' transition to work

This paper contributes to the literature on the drivers of the gender gap in STEM by focusing on a critical career juncture: the bridge between university study in STEM fields and work. We investigate the effect of selected characteristics of recent STEM graduates' university education on the difference between women and men in their likelihood of obtaining STEM occupations shortly after graduation. Using unique data on a large sample of graduates in male-dominated STEM fields, we show that a diversified university curriculum increases the likelihood of women graduates getting STEM occupations shortly after graduation, while it does not affect men. In contrast, doing internships during university studies and participating in study abroad programs reduce the likelihood of men graduates entering STEM occupations, but does not affect women. Additionally, students' graduation grades increase the probability of both women and men securing STEM occupations

Optimization of a perishable inventory system: A simulation study in a Ho.Re.Ca. company

The main goal of this paper is to describe the optimization of the inventory management process in a real context of perishable food products. The study involves one of the largest Italian HO.RE.CA. companies, located in the north of Italy and operating as a provider of the catering, commercial and welfare services. A simulation model was set up with the purpose of adapting three traditional reordering policies (i.e. Re-Order Point, Re-Order Cycle, and (s,S)) to a set of products belonging to company's assortment and evaluating the resulting economic outcomes. To this end, each policy was modelled on Microsoft ExcelTM, so as to compute the total cost of inventory management and determine of the minimum cost strategy. A comparison with the current company's performance and that achievable with the optimized policy is also proposed

CARBOXYLATED-CELLULOSE NANOCRYSTALS PRODUCED FROM LIGNOCELLULOSIC SOURCES AND USED AS BARRIER COATING FOR PET FILMS

The obtainment of Cellulose nanocrystal (CNC) from different cellulosic sources recently gained a great attention due to their physical and mechanical properties. CNC can be extracted from variety of bio-based and renewable sources, such as wood, cotton, bacterial cellulose, tunicate cellulose and softwood cellulose and used as reinforced nanocomposites, functional materials and oxygen-barrier layers. The most important factor affecting the nanocellulose production is the relative proportion of cellulose, hemicellulose, and lignin in the source material. The extraction of CNC from cellulosic materials started with a pre-treatment of biomass involving the complete or partial removal of hemicelluloses, lignin, etc. and isolation of cellulose component. After the separation of matrix materials, controlled hydrolysis of the cellulosic fibers is performed in order to produce colloidal suspensions of cellulose crystals. Using of ammonium persulfate (APS) has recently achieved the obtainment of CNC from different cellulose sources without any pre-treatment. APS, a strong oxidizing agent with high water solubility, is able to produce carboxylated CNC having high crystallinity and active carboxyl groups. The conversion of the carboxylic acid groups to the carboxylate form offers active sites for surface modification and templates for the synthesis of nanoparticles. Incorporation of carboxylated–CNC as a functional layer on different substrates have enhanced the barrier (oxygen permeability), mechanical, optical, and antifog properties of the nanocomposites. The aim of this work was to obtain the CNC from two lignocellulosic sources and to characterize them in terms of morphology, crystallinity, charge density and coating properties in order to use CNC as barrier coating for PET films

Organic Acids and Nature Identical Compounds Can Increase the Activity of Conventional Antibiotics Against Clostridium Perfringens and Enterococcus Cecorum In Vitro

SUMMARY In a global context of increased antibiotic resistance, feed additives with enhanced antimicrobial properties are a useful and increasingly needed strategy. Organic acids (OA) and botanical molecules such as nature identical compounds (NIC) have been shown to be effective against bacterial infections based on their antimicrobial activity. The aim of this study was to evaluate whether the combination of OA or NIC with conventional antibiotics in poultry could increase antibiotic efficacy against Clostridium perfringens and Enterococcus cecorum. These organisms are the major poultry pathogens responsible for necrotic enteritis and bacterial chondronecrosis with osteomyelitis, respectively, and they have developed resistance to several antibiotics worldwide. A set of antimicrobial tests showed that both species had variable antibiotic sensitivity. Alternatively, OA and NIC were always effective in a dose-dependent manner, even when the antibiotics failed. For several strains, selected combinations of OA or NIC with antibiotics increased the bacterial sensitivity to antibiotics. Therefore, OA and NIC have potential to enhance the efficacy of conventional antibiotics against C. perfringens andE. cecorum

Pediocin A improves growth performance of broilers challenged with Clostridium perfringens

The aim of this study was to investigate the efficacy of the anticlostridial pediocin A from Pediococcus pentosaceus FBB61 to contain negative effects associated to Clostridium proliferation in broilers, through 2 subsequent investigations. In the first study, 36 Ross 508 broilers were divided into 3 groups and fed for 21 d as follows: the control diet (CTR), the control diet supplemented with supernatant filtrate of a culture of P. pentosaceus FBB61-2 (Bac−, isogenic mutant nonproducing pediocin A), and the control diet supplemented with supernatant filtrate of a culture of P. pentosaceus FBB61 (Bac+) containing pediocin A. Birds were challenged with 106 cells of Clostridium perfringens. In the second study, 216 Ross 508 broilers were allocated in 18 pens and divided into 3 groups fed the same diet for 42 d: a control group (CTR), a group challenged with 108 cells of C. perfringens (CP), and a group challenged with 108 cells of C. perfringens and receiving the control diet supplemented with P. pentosaceus FBB61 and pediocin A (PA). Broiler BW, ADG, ADFI, and feed conversion rate were measured throughout the studies. At the end of both experiments, an appropriate number of birds was killed and analyzed for necrotic enteritis lesions and microbiological examinations. In the first study, on d 9, ADG and BW were 20% higher for Bac+ compared with CTR and Bac−; on d 14, ADG was higher for Bac+ (+23%, P < 0.05), whereas BW was higher for Bac+ and Bac− compared with CTR (+23 and +14%, respectively; P < 0.05). In the second study, on d 14, ADG and BW were higher for PA compared with CTR and CP (+15% on average; P < 0.05), whereas between 15 and 42 d, there was only a tendency toward a higher ADG for PA when compared with the CP group (+4%, P = 0.08). Diet supplementation with pediocin A improved broiler growth performance during the challenge with C. perfringens and tended to restore the ADG depletion during the 42-d period

Linear Chains of Styrene and Methyl-Styrene Molecules and their Heterojunctions on Silicon: Theory and Experiment

We report on the synthesis, STM imaging and theoretical studies of the structure, electronic structure and transport properties of linear chains of styrene and methyl-styrene molecules and their heterojunctions on hydrogen-terminated dimerized silicon (001) surfaces. The theory presented here accounts for the essential features of the experimental STM data including the nature of the corrugation observed along the molecular chains and the pronounced changes in the contrast between the styrene and methyl-styrene parts of the molecular chains that are observed as the applied bias is varied. The observed evolution with applied bias of the STM profiles near the ends of the molecular chains is also explained. Calculations are also presented of electron transport along styrene linear chains adsorbed on the silicon surface at energies in the vicinity of the molecular HOMO and LUMO levels. For short styrene chains this lateral transport is found to be due primarily to direct electron transmission from molecule to molecule rather than through the silicon substrate, especially in the molecular LUMO band. Differences between the calculated position-dependences of the STM current around a junction of styrene and methyl-styrene molecular chains under positive and negative tip bias are related to the nature of lateral electron transmission along the molecular chains and to the formation in the LUMO band of an electronic state localized around the heterojunction.Comment: 17 pages plus 11 figures. To appear in Physical Review