646 research outputs found
The One-Armed Spiral Instability in Neutron Star Mergers and its Detectability in Gravitational Waves
No full text<p>We distribute complete gravitational-wave signals in the Advanced LIGO band (10 Hz - 8192 Hz) of the inspiral and merger of two neutron stars. These waveforms been constructed by hybridizing numerical-relativity data obtained with the WhiskyTHC code [1] with tidal effective-one-body waveforms [2,3]. More details on the procedure used to generate these waveforms are given in [4]. </p>
<p>The waveforms are distributed as HDF5 files containing the amplitude and phase of the -2 spin-weighted spherical harmonics multipoles of the strain:</p>
<p><span class="math-tex"></span></p>
<p>where <span class="math-tex"></span> is the distance in cm from the source.</p>
<p>The data files include a machine readable "/metadata" group with:</p>
<ul>
<li>/metadata/EOS: name of the equation of state</li>
<li>/metadata/M_{A|B}: mass in isolation of star A (or B) in grams</li>
<li>/metadata/R_{A|B}: radius of star A (or B) in cm</li>
<li>/metadata/k2T: tidal coupling constant of the binary (see [3])</li>
<li>/metadata/kl_{A|B}: l=2,3,4 dimensionless Love numbers of star A (or B)</li>
</ul>
<p>We store amplitude and phase for multipoles modes up to l=4 as time series sampled at 16384 Hz.</p>
<p>We make these waveforms freely available in the hope that they will be useful. We kindly ask you to cite [3] and [4] in any publication resulting from the use of these waveforms.</p>
<p>---<br />
[1] http://www.tapir.caltech.edu/~david_e/whiskythc.html<br />
[2] https://eob.ihes.fr/<br />
[3] S. Bernuzzi, A. Nagar, T. Dietrich, T. Damour; Modeling the Dynamics of Tidally Interacting Binary Neutron Stars up to the Merger; Phys.Rev.Lett. 114 (2015) 16, 161103.<br />
[4] D. Radice, S. Bernuzzi, C. D. Ott; The One-Armed Spiral Instability in Neutron Star Mergers and its Detectability in Gravitational Waves; arXiv:1603.05726.</p>
Controlli dimensionali di prodotti in acciaio per impieghi strutturali: misure, tolleranze, incertezza ed associati livelli di rischio
No full textQuesta nota affronta la specifica tematica della conformità di
prodotti impiegati per realizzare strutture in acciaio ed in particolare
la rispondenza alle specifiche dimensionali sulla base
di una corretta impostazione metrologica del processo di misura.
In dettaglio, a fronte di una schematica introduzione, viene
posta l’attenzione su misure, incertezza di misura ed associati
livelli di rischio in relazione alle tolleranze previste dalle specifiche
normative. Viene poi proposto un concreto esempio applicativo,
riferito a rotoli in acciaio (coils) per la realizzazione di
prodotti strutturali (travi, colonne e lamiere grecate), considerando
le prescrizioni dimensionali di accettabilità fornite dalla
normativa in termini di tolleranza sullo spessore e valutando
l’accettabilità o meno del prodotto
QUSDRA APPROACH: QUICK SEISMIC DESIGN OF STEEL STORAGE RACKS
No full textThe paper is focused on the seismic performance of steel storage pallet racks, which represent a very competitive solution, widely used to store goods and materials. In particular, the design strategy herein proposed is based on a procedure which directly correlate the static and the seismic rack performance using the so-called Incremental Dynamic Analysis (IDA) approach. Despite this approach is a well-established analysis method, generally used for defining the risk associated with seismic events, it is rarely employed in the routine design of steel racks. In fact, independently of the complexity of the racks under investigation, only the modal response spectrum analysis (MRSA) is usually adopted, neglecting hence some non-negligible peculiarities of these structures. This is mainly due to the lack of time during the design phases.
The proposed procedure, named QUSDRA (QUick Seismic Design of steel storage RAcks), allows designers to choose the more convenient structural solution by considering both costs and the key structural performance parameters (i.e. reduction of the load carrying capacity, transient interstorey drift and residual interstorey drift), with limited computational efforts. In fact, QUSDRA method is directly based on an IDA database which, once created, can be used for the rack design on different seismic area.
In order to better understand the key phases of the procedure, a step-by-step case study is presented, highlighting the main advantages associated with the proposed approach
A precious metal: iron, an essential nutrient for all cells
No full textIron is an important cofactor required for a no. of essential cell junctions and hence is a vital nutrient. However, iron can also be dangerous as a catalyst of free radical reactions. Accordingly, intracellular iron homeostasis and body iron balance are tightly regulated. In this review, we presented an overview of the remarkable new insights that over the last years have been gained into the multifaceted and sophisticated mol. mechanisms controlling iron acquisition, storage and release. We also reviewed the data about nutrition-related abnormalities of iron metab., such as iron overload and deficiency. Finally, we discussed how pathogenic microorganisms and host cells compete for iron, a battle whose outcome has a relevant role in infection disease
Gravitational waveforms from binary neutron star mergers with high-order weighted-essentially-nonoscillatory schemes in numerical relativity
No full textThe theoretical modeling of gravitational waveforms from binary neutron star mergers requires precise numerical relativity simulations. Assessing convergence of the numerical data and building the error budget is currently challenging due to the low accuracy of general-relativistic hydrodynamics schemes and to the grid resolutions that can be employed in (3+1)-dimensional simulations. In this work, we explore the use of high-order weighted-essentially-non-oscillatory (WENO) schemes in neutron star merger simulations and investigate the accuracy of the waveforms obtained with such methods. We find that high-order WENO schemes can be robustly employed for simulating the inspiral-merger phase and they significantly improve the assessment of the waveform's error budget with respect to finite-volume methods. High-order WENO schemes can be thus efficiently used for high-quality waveforms production, also in future large-scale investigations of the binary parameter space
La fuga silenziosa: esplorazione del fenomeno del Quiet Quitting attraverso una scoping review
No full textIntroduzione. Il Quite Quitting (QQ), inteso come impegno limitato dei dipendenti verso il proprio lavoro e riluttanza ad assumere compiti facoltativi ed extraruolo, ha destato attenzione a partire dalla pandemia di COVID-19. Tuttavia, recenti ricerche suggeriscono che il fenomeno potrebbe non essere del tutto nuovo poiché sovrapponibile ad altri costrutti. Ciò evidenzia la necessità di approfondire la conoscenza del fenomeno al fine di assicurare uno sviluppo teorico coerente.
Obiettivi. Questo studio ha l’obiettivo di esplorare le relazioni del QQ con altri costrutti rilevanti nel contesto organizzativo.
Metodo. Per rispondere a questo obiettivo è stata condotta una scoping review. Seguendo il metodo PRISMA, 9 articoli sono stati inclusi tramite una ricerca sui database Scopus, Web of Science e Psycinfo. I risultati verranno presentati seguendo il framework della Theory Context Characteristic Method e il Nomological network.
Risultati. Dall’analisi emerge che i 9 articoli selezionati sono stati pubblicati tra il 2022 e il 2024, coerentemente con la crescente attenzione verso il fenomeno. Due di questi studi propongono validazioni di scale di misura, fornendo preliminari evidenze rispetto alla distinzione tra il QQ e differenti costrutti psicologici come la job satisfaction, il burnout e il turnover. I principali costrutti che si rivelano essere determinanti nell'aumentare il QQ, sono burnout, stress, violazione del contratto psicologico, discriminazioni e molestie. A ridurre la sua diffusione sono invece supporto sociale, benessere, soddisfazione lavorativa, opportunità di sviluppo, coinvolgimento e impegno nel lavoro.
Limiti. La maggioranza degli studi inclusi presentano un disegno di ricerca trasversale, suggerendo la necessità di studi longitudinali per confermare le relazioni causali tra costrutti.
Aspetti innovativi. Proponendo spunti di riflessione e domande aperte, la presente revisione della letteratura sottolinea la necessità di sviluppare ulteriori studi empirici al fine di comprendere, concettualizzare e misurare efficacemente il fenomeno del QQ
Old trends in new clothing? Exploring the quiet quitting phenomenon through a scoping review
No full textQuite Quitting (QQ), defined as employees' limited engagement with work and reluctance to take on extra or non-essential tasks, gained attention in the post-pandemic era. However, recent studies suggest that QQ might not represent an entirely novel phenomenon, indicating a need for further exploration to ensure coherent theoretical development. Through a scoping review, this paper aims to synthesize the literature on QQ, mapping its antecedents and consequences. Following the PRISMA guidelines, 22 articles sourced from Scopus, Web of Science, PsycINFO, and Econlit were analyzed using the Theory, Context, Characteristic, Method and the Nomological Network frameworks. The analysis of the articles, published between 2022 and 2024, revealed a growing interest in this topic. Although a universal definition did not emerge, common themes were identified across the several definitions provided: minimal effort, absence of formal resignation, prioritization of work-life balance, disengagement and coping with stress. Additionally, the nomological network showed occupational health factors, personal and job resources, work attitudes, behaviors, and risk factors as predictors of QQ. Well-being, burnout, and job satisfaction emerged as critical mediators in understanding QQ behaviors. Notably, the review identifies turnover intention as a primary outcome linked to QQ. However, most studies employed cross-sectional designs, underscoring the need for longitudinal research to confirm causal relationships. This scoping review is the first to thoroughly examine QQ, highlighting its complexities and emphasizing the need for further research to recognize QQ not merely as “an old trend in new clothing” but as a distinct phenomenon with unique challenges and potential benefits
Tidal polarizability effects in neutron star mergers
No full textAbstract Using the analytical effective-one-body model and nonlinear 3+1 numerical relativity simulations, we investigate binary neutron star mergers. It is found that, for nonspinning binaries, both the mass-rescaled gravitational wave frequency at merger and the specific binding energy at merger almost uniquely depend on the tidal coupling constants κ T 2 , which are functions of the stars’ Love numbers, compactnesses and mass ratio. These relations are quasiuniversal in the sense that there is an additional dependence on the spins, which is linear for realistic spins values χ ≲ 0.1. In the effective-one-body model, the quasiuniversality is a direct consequence of the conservative dynamics of tidally interacting bodies. In the context of gravitational wave astronomy, our findings may be used to constrain the neutron stars’ equation of state using waveforms that accurately model the merger
Structural steel components under low-cycle fatigue: Design assisted by testing
No full textS. FRANCISCO, CA; on CD Ro
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