815 research outputs found

    Dynamics underlying Box-office: Movie Competition on Recommender Systems

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    We introduce a simple model to study movie competition in the recommender systems. Movies of heterogeneous quality compete against each other through viewers' reviews and generate interesting dynamics of box-office. By assuming mean-field interactions between the competing movies, we show that run-away effect of popularity spreading is triggered by defeating the average review score, leading to hits in box-office. The average review score thus characterizes the critical movie quality necessary for transition from box-office bombs to blockbusters. The major factors affecting the critical review score are examined. By iterating the mean-field dynamical equations, we obtain qualitative agreements with simulations and real systems in the dynamical forms of box-office, revealing the significant role of competition in understanding box-office dynamics.Comment: 8 pages, 6 figure

    Non-Financial Resources to Enhance Companies’ Profitability: A Stakeholder Perspective

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    Purpose This study aims to investigate the impact of stakeholders’ nonfinancial resources (NFRs) on companies’ profitability, filling a significant gap in the literature regarding the role of NFRs in value creation. Design/methodology/approach Data from 76 organizations from 2017 to 2019 were collected and analyzed. Four primary NFRs and their key value drivers were identified, representing core elements that support different dimensions of a company’s performance. Statistical tests examined the relationship between stakeholders’ NFRs and financial performance measures. Findings When analyzed collectively and individually, the results reveal a significant positive influence of stakeholders’ NFRs on a firm’s profitability. Higher importance assigned to NFRs correlates with a higher return on sales. Originality/value This study contributes to the literature by empirically bridging the gap between stakeholder theory and the resource-based view, addressing the intersection of these perspectives. It also provides novel insights into how stakeholders’ NFRs impact profitability, offering valuable implications for research and managerial practice. It suggests that managers should integrate nonfinancial measures of NFRs within their performance measurement system to manage better and sustain companies’ value-creation process

    True scale-free networks hidden by finite size effects

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    We analyze about two hundred naturally occurring networks with distinct dynamical origins to formally test whether the commonly assumed hypothesis of an underlying scale-free structure is generally viable. This has recently been questioned on the basis of statistical testing of the validity of power law distributions of network degrees by contrasting real data. Specifically, we analyze by finite-size scaling analysis the datasets of real networks to check whether purported departures from the power law behavior are due to the finiteness of the sample size. In this case, power laws would be recovered in the case of progressively larger cutoffs induced by the size of the sample. We find that a large number of the networks studied follow a finite size scaling hypothesis without any self-tuning. This is the case of biological protein interaction networks, technological computer and hyperlink networks, and informational networks in general. Marked deviations appear in other cases, especially infrastructure and transportation but also social networks. We conclude that underlying scale invariance properties of many naturally occurring networks are extant features often clouded by finite-size effects due to the nature of the sample data

    Forecast indices from a ground-based microwave radiometer for operational meteorology

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    Abstract. Today, commercial microwave radiometer profilers (MWRPs) are robust and unattended instruments providing real-time, accurate atmospheric observations at ~ 1 min temporal resolution under nearly all weather conditions. Common commercial units operate in the 20–60 GHz frequency range and are able to retrieve profiles of temperature, vapour density, and relative humidity. Temperature and humidity profiles retrieved from MWRP data are used here to feed tools developed for processing radiosonde observations to obtain values of forecast indices (FIs) commonly used in operational meteorology. The FIs considered here include K index, total totals, KO index, Showalter index, T1 gust, fog threat, lifted index, S index (STT), Jefferson index, microburst day potential index (MDPI), Thompson index, TQ index, and CAPE (convective available potential energy). Values of FIs computed from radiosonde and MWRP-retrieved temperature and humidity profiles are compared in order to quantitatively demonstrate the level of agreement and the value of continuous FI updates. This analysis is repeated for two sites at midlatitude, the first one located at low altitude in central Europe (Lindenberg, Germany) and the second one located at high altitude in North America (Whistler, Canada). It is demonstrated that FIs computed from MWRPs well correlate with those computed from radiosondes, with the additional advantage of nearly continuous updates. The accuracy of MWRP-derived FIs is tested against radiosondes, taken as a reference, showing different performances depending upon index and environmental situation. Overall, FIs computed from MWRP retrievals agree well with radiosonde values, with correlation coefficients usually above 0.8 (with few exceptions). We conclude that MWRP retrievals can be used to produce meaningful FIs, with the advantage (with respect to radiosondes) of nearly continuous updates

    Global transcriptional response of Saccharomyces cerevisiae to the deletion of SDH3

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    <p>Abstract</p> <p>Background</p> <p>Mitochondrial respiration is an important and widely conserved cellular function in eukaryotic cells. The succinate dehydrogenase complex (Sdhp) plays an important role in respiration as it connects the mitochondrial respiratory chain to the tricarboxylic acid (TCA) cycle where it catalyzes the oxidation of succinate to fumarate. Cellular response to the Sdhp dysfunction (i.e. impaired respiration) thus has important implications not only for biotechnological applications but also for understanding cellular physiology underlying metabolic diseases such as diabetes. We therefore explored the physiological and transcriptional response of <it>Saccharomyces cerevisiae </it>to the deletion of <it>SDH3</it>, that codes for an essential subunit of the Sdhp.</p> <p>Results</p> <p>Although the Sdhp has no direct role in transcriptional regulation and the flux through the corresponding reaction under the studied conditions is very low, deletion of <it>SDH3 </it>resulted in significant changes in the expression of several genes involved in various cellular processes ranging from metabolism to the cell-cycle. By using various bioinformatics tools we explored the organization of these transcriptional changes in the metabolic and other cellular functional interaction networks.</p> <p>Conclusion</p> <p>Our results show that the transcriptional regulatory response resulting from the impaired respiratory function is linked to several different parts of the metabolism, including fatty acid and sterol metabolism.</p

    Analysis of Radiosonde and Ground-Based Remotely Sensed PWV Data from the 2004 North Slope of Alaska Arctic Winter Radiometric Experiment

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    Abstract During 9 March–9 April 2004, the North Slope of Alaska Arctic Winter Radiometric Experiment was conducted at the Atmospheric Radiation Measurement Program's (ARM) "Great White" field site near Barrow, Alaska. The major goals of the experiment were to compare microwave and millimeter wavelength radiometers and to develop forward models in radiative transfer, all with a focus on cold (temperature from 0° to −40°C) and dry [precipitable water vapor (PWV) &lt; 0.5 cm] conditions. To supplement the remote sensors, several radiosonde packages were deployed: Vaisala RS90 launched at the ARM Duplex and at the Great White and Sippican VIZ-B2 operated by the NWS. In addition, eight dual-radiosonde launches were conducted at the Duplex with Vaisala RS90 and Sippican GPS Mark II, the latter one modified to include a chilled mirror humidity sensor. Temperature comparisons showed a nighttime bias between VIZ-B2 and RS90, which reached 3.5°C at 30 hPa. Relative humidity comparisons indicated better than 5% average agreement between the RS90 and the chilled mirror. A bias of about 20% for the upper troposphere was found in the VIZ-B2 and the Mark II measurements relative to both RS90 and the chilled mirror. Comparisons in PWV were made between a microwave radiometer, a microwave profiler, a global positioning system receiver, and the radiosonde types. An RMS agreement of 0.033 cm was found between the radiometer and the profiler and better than 0.058 cm between the radiometers and GPS. RS90 showed a daytime dry bias on PWV of about 0.02 cm

    3DVAR assimilation of SSM/I data over the sea for the IOP2b MAP case

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    International audienceData assimilation by 3DVAR of data from the Special Sensor Microwave/Imager (SSM/I) has been performed to study the IOP2b case (19-21 September 1999) of the Mesoscale Alpine Programme (MAP). Only data over the sea surface are used to avoid the contamination of the surface emissivity. Moreover, the rainy data are filtered out because the assimilation algorithm of 3DVAR does not take into account the scattering processes. SSM/I data are assimilated in two different ways: as Brightness Temperature directly, or as Precipitable Water and surface wind speed retrieved from the Brightness Temperature. The effect of the thinning of the observations has been studied and a set of sensitivity test cases has been carried out; the one by one removal of the SSM/I frequencies from the initial dataset allows to evaluate their impact on the Initial Conditions. A few experiments are performed using these new Initial Conditions to initialize the MM5 (PSU/NCAR) model. The results show that the assimilation of the retrieved quantities, i.e. Precipitable Water and surface wind speed, does not produces large improvement in the Initial Conditions. Vice versa, the assimilation of the Brightness temperatures produces a large variability of the Initial Conditions. The forecast experiments show that the model is very sensitive to the 22GHz and 37GHz frequencies

    Visualization of actin filaments and monomers in somatic cell nuclei

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    © The Author(s), 2013. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Molecular Biology of the Cell 24 (2013): 982-994, doi:10.1091/mbc.E12-09-0685.In addition to its long-studied presence in the cytoplasm, actin is also found in the nuclei of eukaryotic cells. The function and form (monomer, filament, or noncanonical oligomer) of nuclear actin are hotly debated, and its localization and dynamics are largely unknown. To determine the distribution of nuclear actin in live somatic cells and evaluate its potential functions, we constructed and validated fluorescent nuclear actin probes. Monomeric actin probes concentrate in nuclear speckles, suggesting an interaction of monomers with RNA-processing factors. Filamentous actin probes recognize discrete structures with submicron lengths that are excluded from chromatin-rich regions. In time-lapse movies, these actin filament structures exhibit one of two types of mobility: 1) diffusive, with an average diffusion coefficient of 0.06–0.08 μm2/s, or (2) subdiffusive, with a mobility coefficient of 0.015 μm2/s. Individual filament trajectories exhibit features of particles moving within a viscoelastic mesh. The small size of nuclear actin filaments is inconsistent with a role in micron-scale intranuclear transport, and their localization suggests that they do not participate directly in chromatin-based processes. Our results instead suggest that actin filaments form part of a large, viscoelastic structure in the nucleoplasm and may act as scaffolds that help organize nuclear contents.This bulk of this work was supported by a grant from the National Institutes of Health to R.D.M. (5R01GM061010-12). Additional support was provided by National Institutes of Health Grant R01 CA096840 (E.H.B.), a National Science Foundation Predoctoral Fellowship (B.B.), a National Institutes of Health Ruth L. Kirschstein Predoctoral Fellowship (B.B.), and a Genentech Fellowship (B.C.)

    Study of recent seismicity in the area of Southern Apennines

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    In questo lavoro è stata effettuata una dettagliata analisi della sismicità dell’Italia meridionale in particolare della zona comprendente l’Appennino lucano e l’avanfossa bradanica. Sono stati utilizzati i tempi d’arrivo delle fasi P e S di terremoti locali registrati dalla Rete Sismica Nazionale (RSNC), dalla rete temporanea SAPTEX (2001-2004) (Cimini et al., 2006), e dalla rete locale dell’Eni-Agip operante nella Val d’Agri, registrate nel periodo 2001-2006. In questo modo è stato creato un database costituito da 7570 fasi P e 4956 fasi S, associate a 514 eventi con magnitudo maggiore di 2.0. Lo studio realizzato consiste nel: 1) Calcolo del rapporto VP/VS utilizzando il metodo di Wadati modificato (Chatelain, 1978), ottenendo un valore di 1.83 (Fig.1) leggermente superiore a quello ottenuto da studi precedenti; 2) Analisi del profilo di velocità 1D che meglio approssima la struttura crostale dell’area studiata (Fig.2) utilizzando il codice VELEST (Kissling et al., 1995) e tre modelli iniziali ottenuti da studi precedenti (Chiarabba and Frepoli, 1997; Cassinis et al., 2003; Chiarabba at al., 2005; Frepoli et al., 2005). 3) Localizzazione ipocentrale, calcolo dei meccanismi focali e campo di stress. Le localizzazioni ipocentrali calcolate sono prevalentemente di qualità A(243) e B(59), così come definite dal programma HYPOELLIPSE (Lahr, 1989). Rispetto a quelle ottenute utilizzando i dati della sola rete RSNC, esse risultano avere profondità ipocentrali piú vincolate ed errori di localizzazione inferiori. Considerando la distribuzione della sismicità in Fig.3 si possono distinguere tre zone principali: una situata nella parte ovest della catena appenninica, caratterizzata soprattutto da eventi piú superficiali; una situata in corrispondenza dell’avanfossa bradanica caratterizzata da una sismicità sparsa e da eventi piú profondi; ed infine un gruppo di eventi sparsi localizzati nell’area della Sila, separati da quelli esistenti nella zona del monte Pollino da un evidente gap sismico. Seguendo la procedura di calcolo dei meccanismi focali, col metodo delle polarità dei primi arrivi, ne sono stati selezionati 69 in base ai due fattori di qualità definiti dal codice FPFIT (Reasenberg and Oppenheimer, 1985). Le soluzioni ottenute sono in gran parte normali e trascorrenti con gli assi T che descrivono una generalizzata estensione dell’Appennino lucano in direzione NE-SW. Per la determinazione del campo di stress regionale è stata utilizzata la tecnica di inversione elaborata da Gephart & Forsyth (1984). I risultati ottenuti sono coerenti con i precedenti studi nella stessa area

    Analysis of the trueness and precision of complete denture bases manufactured using digital and analog technologies

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    PURPOSE. Digital technology has enabled improvements in the fitting accuracy of denture bases via milling techniques. The aim of this study was to evaluate the trueness and precision of digital and analog techniques for manufacturing complete dentures (CDs). MATERIALS AND METHODS. Sixty identical CDs were manufactured using different production protocols. Digital and analog technologies were compared using the reference geometric approach, and the Delta-error values of eight areas of interest (AOI) were calculated. For each AOI, a precise number of measurement points was selected according to sensitivity analyses to compare the Delta-error of trueness and precision between the original model and manufactured prosthesis. Three types of statistical analysis were performed: to calculate the intergroup cumulative difference among the three protocols, the intergroup among the AOIs, and the intragroup difference among AOIs. RESULTS. There was a statistically significant difference between the dentures made using the oversize process and injection molding process (P &lt; .001), but no significant difference between the other two manufacturing methods (P = .1227). There was also a statistically significant difference between the dentures made using the monolithic process and the other two processes for all AOIs (P = .0061), but there was no significant difference between the other two processes (P = 1). Within each group, significant differences among the AOIs were observed. CONCLUSION. The monolithic process yielded better results, in terms of accuracy (trueness and precision), than the other groups, although all three processes led to dentures with Delta-error values well within the clinical tolerance limit. [J Adv Prosthodont 2023;15:22-32
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