Dynamics of a Bose-Einstein Condensate of Excited Magnons

The emergence of a non-equilibrium Bose-Einstein-like condensation of magnons in rf-pumped magnetic thin films has recently been experimentally observed. We present here a complete theoretical description of the non-equilibrium processes involved. It it demonstrated that the phenomenon is another example of the presence of a Bose-Einstein-like condensation in non-equilibrium many-boson systems embedded in a thermal bath, better referred-to as Fr\"{o}hlich-Bose-Einstein condensation. The complex behavior emerges after a threshold of the exciting intensity is attained. It is inhibited at higher intensities when the magnon-magnon interaction drives the magnons to internal thermalization. The observed behavior of the relaxation to equilibrium after the end of the pumping pulse is also accounted for and the different processes fully described.Comment: 42 pages, 11 figure

Firm Assets and Investments in Open Source Software Products

Open source software (OSS) has recently emerged as a new way to organize innovation and product development in the software industry. This paper investigates the factors that explain the investment of profit-oriented firms in OSS products. Drawing on the resource-based theory of the firm, we focus on the role played by pre-OSS firm assets both upstream and downstream, in the software and the hardware dimensions, to explain the rate of product introduction in OSS. Using a self-assembled database of firms that have announced releases of OSS products during the period 1995-2003, we find that the intensity of product introduction can be explained by a strong position in software technology and downstream market presence in hardware. Firms with consolidated market presence in proprietary software and strong technological competences in hardware are more reluctant to shift to the new paradigm. The evidence is stronger for operating systems than for applications. The fear of cannibalization, the crucial role of absorptive capacity, and complementarities between hardware and software are plausible explanations behind our findings.Product Introduction, Open Source Software, Absorptive Capacity

A novel topology for a HEMT negative current mirror

A new solution for the implementation of a HEMT negative current source is presented. The topology can be also profitably employed as a current mirror and as an active load in high-gain MMICs voltage amplifiers. A small-signal model of the proposed circuit is developed which allows to find accurate expressions for the required transfer functions (i.e., the output impedance of the current source, and the current gain of the circuit when operated as a current mirror). Design examples using Philips PML ED02AH GaAs PHEMT process are provided. Spice simulations show that a 10- kW output impedance for the current source and a 35dB voltage gain for a differential pair loaded with the proposed current mirror are easily achieved

What memory binding functions is the hippocampus responsible for?

The role of the hippocampus in binding information in working memory (WM) is little understood. When complex experiences comprise associations between different pieces of information such as objects and locations (relational binding), the function of the hippocampus is required to hold them in WM (Mitchell et al., 2000; 2006; Piekema, 2006). However, recent evidence suggests that if the to-be-associated information leads to the formation of integrated objects such as coloured shapes (conjunctive binding), the hippocampus is less involved in holding temporary representations of these complex events in WM (Baddeley et al., 2010; Piekema, 2006). We investigated the relational and conjunctive binding hypotheses of the hippocampal functions in a patient with right hippocampal damage. The patient and controls were asked to study visual arrays of stimuli which consisted of shape-colour relations (shape-colour pairs) or shape-colour conjunctions (coloured shapes). After the study array, they were presented with a new screen consisting of one set of shapes (line drawings) and one set of colours. They were asked to reconstruct the bindings by selecting the shapes and their corresponding colours. As compared to healthy controls, the patient was impaired in holding relations of shapes and colours in WM whereas he could retain the conjunctions similarly to controls. These results lend support to the role of the hippocampus in supporting memory for inter-item associations but not memory for conjunctions of features which define objects' identity

Seasonal undernutrition in rural Ethiopia:

Marked seasonal variability of both production- and consumption is characteristic of virtually all farming systems in the developing world. This study examines the magnitude and significance of seasonal undernutrition in south central Ethiopia, southern Shewa and Zigwa Boto, a peasant association in the Gurage Zone. The study seeks to answer five questions: (1)Does seasonal energy stress affect individuals of various age groups and sexes differently? (2)Do members of the same household show divergent responses to seasonal energy stress? (3)What are the functional consequences of different levels of adult undernutrition? (4)Are the current anthropometric cut-off points for adults appropriate for rural Ethiopia? (5)What household characteristics are associated with vulnerability to seasonal undernutrition? A number of important findings emerge from this research.....The study clarifies some points of contention in the field of adult undernutrition and shows how seasonal undernutrition operates as an intermittent warning signal, reminding us not to miss opportunities to promote good nutrition throughout the life cycle.Nutrition, Ethiopia, Malnutrition., Food crops., Climate.,

The penguin has entered the building: the commercialization of open source software products

Previous literature on open source software (OSS) mostly analyzes organizational issues within communities of developers and users. This paper focuses on for-profit organizations that release software products under OSS licenses, and argues that variations in their endowments of intellectual property rights, namely patents and trademarks, help to determine which firms will tend to incorporate OSS into commercial products. We explain whether and under what conditions preexisting stocks of intellectual property rights can be useful complementary assets that allow firms to benefit directly or indirectly from commercializing OSS products, and test our hypotheses on a novel data set built on firms’ announcements of OSS product releases in the specialized press between 1995 and 2003. We find three robust results: (a) firms with large stocks of software patents are more likely to release OSS products; (b) firms with large stocks of software trademarks are less likely to release OSS products; (c) firms with large stocks of hardware trademarks are more likely to release OSS products.Publicad

Investigation of Lunar Surface Chemical Contamination by LEM Descent Engine and Associated Equipment

Lunar surface and atmospheric contamination study caused by LEM rocket exhaust and inorganic, organic, and microbiological contaminant

Questioning the validity of non-extensive thermodynamics for classical Hamiltonian systems

We examine the non-extensive approach to the statistical mechanics of Hamiltonian systems with $H=T+V$ where $T$ is the classical kinetic energy. Our analysis starts from the basics of the formalism by applying the standard variational method for maximizing the entropy subject to the average energy and normalization constraints. The analytical results show (i) that the non-extensive thermodynamics formalism should be called into question to explain experimental results described by extended exponential distributions exhibiting long tails, i.e. $q$-exponentials with $q>1$, and (ii) that in the thermodynamic limit the theory is only consistent in the range $0\leq q\leq1$ where the distribution has finite support, thus implying that configurations with e.g. energy above some limit have zero probability, which is at variance with the physics of systems in contact with a heat reservoir. We also discuss the ($q$-dependent) thermodynamic temperature and the generalized specific heat.Comment: To appear in EuroPhysics Letter

Targeting the medulloblastoma: A molecular-based approach

Background: The lack of success of standard therapies for medulloblastoma has highlighted the need to plan a new therapeutic approach. The purpose of this article is to provide an overview of the novel treatment strategies based on the molecular characterization and risk categories of the medulloblastoma, also focusing on up-to-date relevant clinical trials and the challenges in translating tailored approaches into clinical practice. Methods: An online search of the literature was carried out on the PubMed/MEDLINE and ClinicalTrials.gov websites about molecular classification of medulloblastomas, ongoing clinical trials and new treatment strategies. Only articles in the English language and published in the last five years were selected. The research was refined based on the best match and relevance. Results: A total 58 articles and 51 clinical trials were analyzed. Trials were of phase I, II, and I/II in 55%, 33% and 12% of the cases, respectively. Target and adoptive immunotherapies were the treatment strategies for newly diagnosed and recurrent me-dulloblastoma in 71% and 29% of the cases, respectively. Conclusion: Efforts are focused on the fine-tuning of target therapies and immunotherapies, including agents directed to specific pathways, engineered T-cells and oncoviruses. The blood-brain barrier, chemoresistance, the tumor microenvironment and cancer stem cells are the main translational challenges to be overcome in order to optimize medulloblastoma treatment, reduce the long-term morbidity and increase the overall survival. (www.actabiomedica.it)