1,088 research outputs found
The Cooperative Organization: Economic, Organisational and Policy Issues
Is cooperative action modern or old fashioned? Why should policymakers pursue it in development strategies? In what way are cooperatives different in terms of economic theory and organisation theory? And if there are differences in organisation, human resource management practices, property rights and forms of collective action, what are the governance issues to be addressed so as to allow cooperatives to operate and grow correctly? Taking recent Italian debate about a controversial takeover bid launched by Italian cooperatives in the banking sector as its starting point, this paper endeavours to put forward some general answers with validity for the international cooperative movement as a whole.cooperatives; collective action; cooperation; lifecycle; organization
3D reconstruction with consumer Time-of-Flight sensors
This work shows how it is possible to perform reliable reconstructions of 3D scenes captured with Time-of-Flight consumer sensors. A reconstruction algorithm has been upgraded introducing a more advanced strategy for the fusion task. A software application able to process data acquired form the Creative Senz3D and the Microsoft Kinect for Xbox One has been implemented. A series of experimental measurements has been conducted to evaluate the accuracy and the performancesopenEmbargo per motivi di segretezza e/o di proprietà dei risultati e/o informazioni sensibil
Radio recombination lines from obscured quasars with the SKA
We explore the possibility of detecting hydrogen radio recombination lines
from 0 < z < 10 quasars. We compute the expected Hnalpha flux densities as a
function of absolute magnitude and redshift by considering (i) the range of
observed AGN spectral indices from UV to X-ray bands, (ii) secondary
ionizations from X-ray photons, and (iii) stimulated emission due to nonthermal
radiation. All these effects are important to determine the line fluxes. We
find that the combination of slopes: alpha_X,hard = -1.11, alpha_X,soft = -0.7,
alpha_EUV = -1.3, alpha_UV = -1.7, maximizes the expected flux, f_Hnalpha = 10
microJy for z = 7 quasars with M_AB = -27 in the n = 50 lines; allowed SED
variations produce variations by a factor of 3 around this value. Secondaries
boost the line intensity by a factor of 2 to 4, while stimulated emission in
high-z quasars with M_AB = -26 provides an extra boost to RRL flux observed at
nu = 1 GHz if recombinations arise in HII regions with T_e = 10^3-5 K, n_e =
10^3-5 cm^-3. We compute the sensitivity required for a 5sigma detection of
Hnalpha lines using the SKA, finding that the SKA-MID could detect sources with
M_AB < -27 (M_AB < -26) at z < 8 (z < 3) in less than 100 hrs of observing
time. These observations could open new paths to searches for obscured SMBH
progenitors, complementing X-ray, optical/IR and sub-mm surveys.Comment: 11 pages, 9 figures; to be published in Monthly Notices of the Royal
Astronomical Society Main Journa
A Framework for Transactional Consistency Models with Atomic Visibility
Modern distributed systems often rely on databases that achieve scalability by providing only weak guarantees about the consistency of distributed transaction processing. The semantics of programs interacting with such a database depends on its consistency model, defining these guarantees. Unfortunately, consistency models are usually stated informally or using disparate formalisms, often tied to the database internals. To deal with this problem, we propose a framework for specifying a variety of consistency models for transactions uniformly and declaratively. Our specifications are given in the style of weak memory models, using structures of events and relations on them. The specifications are particularly concise because they exploit the property of atomic visibility guaranteed by many consistency models: either all or none of the updates by a transaction can be visible to another one. This allows the specifications to abstract from individual events inside transactions. We illustrate the use of our framework by specifying several existing consistency models. To validate our specifications, we prove that they are equivalent to alternative operational ones, given as algorithms closer to actual implementations. Our work provides a rigorous foundation for developing the metatheory of the novel form of concurrency arising in weakly consistent large-scale databases
Long-term impact risk for (101955) 1999 RQ36
The potentially hazardous asteroid (101955) 1999 RQ36 has the possibility of
collision with the Earth in the latter half of the 22nd century, well beyond
the traditional 100-year time horizon for routine impact monitoring. The
probabilities accumulate to a total impact probability of approximately 10E-3,
with a pair of closely related routes to impact in 2182 comprising more than
half of the total. The analysis of impact possibilities so far in the future is
strongly dependent on the action of the Yarkovsky effect, which raises new
challenges in the careful assessment of longer term impact hazards.
Even for asteroids with very precisely determined orbits, a future close
approach to Earth can scatter the possible trajectories to the point that the
problem becomes like that of a newly discovered asteroid with a weakly
determined orbit. If the scattering takes place late enough so that the target
plane uncertainty is dominated by Yarkovsky accelerations then the thermal
properties of the asteroid,which are typically unknown, play a major role in
the impact assessment. In contrast, if the strong planetary interaction takes
place sooner, while the Yarkovsky dispersion is still relatively small compared
to that derived from the measurements, then precise modeling of the
nongravitational acceleration may be unnecessary.Comment: Reviewed figures and some text change
Solitary Internal Mammary Lymph Node Metastases Detected by 18F-FDG-PET/CT in Ovarian Cancer
Internal mammary lymph nodes as solitary site of recurrent ovarian cancer have not been previously described. In this case report, 3 cases of late and very late isolated recurrence in internal mammary lymph nodes are presented. 18F-FDG-PET/CT allowed the diagnosis which was suspected by the increase of the serum CA-125 level in 2 out of 3 cases. Local treatment, consisting of surgery (in 2 patients) and radiation therapy (in 1 patient), permitted an optimal long-term disease control
Using the capability approach and organizational climate to study occupational health and safety
The Capability Approach, first developed by Amartya Sen, can be used as a mean to analyse occupational health and safety related behaviours. Accidents at work more frequently occur among atypical workers and migrants, making this an interesting context in which to apply Sen’s theoretical framework; namely showing how freedoms, rights, organisational climate and capabilities are important factors in risk prevention. It is logical to expect that workers’ participation and rights should provide a safer environment, but the application of the Capability Approach offers a tool to measure organisational inequalities and their consequences. Furthermore, its application could help to improve occupational health and safety chiefly among atypical workers. In this paper, I consider Safety Capability to encompass the workers' attitude to their own protection, their understanding of safety procedures and the risks they face, and their freedom to ask their organisation to comply with the law and implement safe work processes
TAPPE EVOLUTIVE DEL CONCETTO DI RESPONSABILITA' SOCIALE
L’argomento centrale della presente tesi è rappresentato dalla tematica basata sulla responsabilità sociale. In essa si cercherà di comprendere innanzitutto l’evoluzione esistente nei rapporti tra le imprese e gli Enti pubblici nei confronti del territorio. Dopo questa parte più generale si entrerà nella analisi dell’orientamento basato sulla responsabilità sociale, il quale sarà suddiviso prima considerando il settore privato e successivamente quello pubblico. Nell’esaminare tali ambiti dopo una prima parte prettamente teorica si presenteranno alcune ricerche che permetteranno di capire e quindi di rendere maggiormente chiaro, come questo nuovo concetto si è realmente radicato nel territorio italiano. Successivamente l’attenzione verrà concentrata sul mondo del lavoro considerando come tema centrale le nuove figure lavorative nate proprio da questo nuovo orientamento: l’Energy Manager e il CSR Manager. Infine, considerando la grandissima importanza che viene assegnata alla comunicazione “sociale” in questo periodo storico, si esamineranno con attenzione gli strumenti utilizzati per svolgere tale compito che sono il bilancio ambientale e il bilancio sociale. Per quanto concerne questo ultimo documento verrà esposto il processo che ha portato alla realizzazione dello stesso nella Università di Pisa
Identificazione di sistemi non lineari tramite regressione Gaussiana e applicazione al Wiener-Hammerstein benchmark
Si espone un approccio per l'identificazione di sistemi non lineari e la sua applicazione a un sistema reale di tipo Wiener-Hammerstein. L'algoritmo [Pillonetto] sfrutta la regressione Gaussiana per modellare il sistema come una realizzazione di un campo aleatorio Gaussiano. Esso riduce il problema alla sola determinazione di alcuni iperparametri che forniscono la descrizione completa dell'autocovarianza ad esso associata. Gli iperparametri vengono stimati ottimizzando la loro densitĂ marginale basandosi esclusivamente sui dati di identificazione forniti dal benchmark Wiener-Hammerstein. I risultati sono infine confrontati coi dati appartenenti all'insieme di test dello stesso benchmark per illustrare l'efficacia di questo approccioope
A Model-Based investigation on the effect of Light on Microalgae Growth: Focusing on Photoproduction, Photoregulation and Photoinhibition
Biofuels derived from microalgae may represent a key source for alternative energy vectors. Moreover, microalgae exhibit a great potential for sustainable production of a wide range of commodities and value-added products, including cosmetics, pharmaceuticals and nutraceuticals, which makes them suitable for biorefinery applications. Their high productivity and their ability to accumulate large amounts of lipids, along with their independence from arable land, put them in a competitive position with respect to traditional oil crops. However, the economical and energetic sustainability of large scale microalgae cultivation for biodiesel production are still debated. The most optimistic previsions are in fact based on gross estimates of productivity, derived by extrapolation of laboratory-scale data.
Therefore, the development of reliable mathematical models that are capable of quantitative predictions of the behaviour of large-scale outdoor microalgae culture is of paramount importance. Such models prove especially useful in identifying which parameters have the largest impact on productivity, thereby providing a means for enhancing the growth conditions through design and operational changes. Moreover, accurate forecasts of microalgal growth in the outdoor conditions can lead to a better understanding of the real potential of microalgae-based biofuels.
This Thesis aims of investigating the complex effect of light in the photosynthetic apparatus activity, and its effect on microalgae growth. The work presented in this Thesis follows two general lines. The first contribution has been to propose a general approach for model development. The proposed methodology guides the modelling effort in order to assure both an accurate representation of the calibration data, but most importantly also the identifiability of the model. The identifiability of a model, i.e. the possibility to estimate in accurate and reliable way its parametric set, is in fact, a necessary property for the model to be confidently used in process scale-up and optimization. The proposed methodology has been successfully applied to growth and fluorescence data of the sea water alga Nannochloropsis Salina.
A second contribution is concerned with Pulsed Amplitude Modulation (PAM) fluorometry. A dynamic model of chlorophyll fluorescence has been developed. The model integrates photoproduction, photoregulation and photoinhibition processes in a semi-mechanistic way. The model has been calibrated against fluorescence data of a sample of the microalga Nannochloropsis gaditana. The proposed fluorescence model is capable of quantitative prediction of the state of the photosynthetic apparatus of microalgae in terms of their open, closed and damaged reaction centres under variable light conditions. Two promising application of the fluorescence model have also been analysed: (i) the model has been used for the prediction of photosynthesis rate versus irradiance (PI)-response curves based on PAM fluorometry; and (ii) a model based experiment design (MBDoE) approach has been followed to define new information rich PAM protocols to further validate and refine the model structure
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