660 research outputs found

    The Ability to Change or the Willingness to Change: Stakeholder Interpretation of Adversity

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    Firms often face adverse environmental events which have the potential to destroy the value the firm has created. This study focuses on the occurrence of adverse events. In particular, we address the research question of what organizational and managerial characteristics impact shareholder interpretation of the severity of the adverse event. Building on insights from the resource based and upper echelon theories, we propose that bundles of firm capabilities and top management team composition signal to shareholders the ability of the firm to handle the adverse event and to engage in strategic change. We test our model in the biotechnology industry, and operationalize an adverse event as a drug terminated during a clinical trial. Our results indicate the importance of the top management team on shareholder perception of event severity

    Methamphetamine abuse and “meth mouth” in Europe

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    With easy chemical synthesis from its precursor, methamphetamine (MA) is now widespread in many countries. The abuse of methamphetamine is associated with several negative effects on health, because MA is a neurotoxin and a dangerous central nervous system stimulant. It changes levels of neurotransmitters in the brain, releasing dopamine and inhibiting nor epinephrine uptake which increases sympathetic nervous system activity and can lead to cardiac arrhythmia, hypertension and tachypnea. The consequences of MA abuse are clearly manifested in oral diseases (like “meth mouth”) which is characterised by extensive caries, teeth grinding with ensuing dental wear and trismus. The present review was designed to fill the gap in knowledge about methamphetamine abuse in the European Union (EU) and to illustrate the main clinical effects of prolonged use. After describing the pharmacology and systemic effects of methamphetamine and concentrating on its effects on the mouth, the present review compares the epidemiology and incidence of abuse in the world, particularly the USA and the EU

    A theoretical-experimental framework for the analysis of the dynamic response of a QEPAS tuning fork device immersed in a fluid medium

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    Quartz-enhanced photoacoustic spectroscopy (QEPAS) is a trace gas sensing technique that employs a designed high-quality factor quartz tuning fork (QTF) as acousto-electric transducer. The first in-plane skew-symmetric flexural mode of the QTF is excited when weak resonant sound waves are generated between the QTF prongs. Thus, the performance of a QEPAS sensor strongly depends on the resonance properties of the QTF, namely the determination of flexural eigenfrequencies and air damping loss. In this work, we present a mixed theoretical-experimental framework to study the dynamic response of a QTF while vibrating in a fluid environment. Due to the system linearity, the dynamic response of the resonator immersed in a fluid medium is obtained by employing a Boundary Element formulation based on an ad hoc calculated Green's function. In particular, the QTF is modelled as constituted by a pair of two Euler-Bernoulli cantilevers partially coupled by a distributed linear spring. As for the forces exerted by the fluid on QTF structure, the fluid inertia and viscosity as well as an additional diffusivity term, whose influence is crucial for the correct evaluation of the system response, have been taken into account. By corroborating the theoretical analysis with the experimental outcomes obtained by means of a vibro-acoustic setup, the fluid response coefficients and the dynamics of the QTF immersed in a fluid environment are fully determined

    Potential Use of MALDI-ToF Mass Spectrometry for Rapid Detection of Antifungal Resistance in the Human Pathogen Candida glabrata.

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    The echinocandins are relatively new antifungal drugs that represent, together with the older azoles, the recommended and/or preferred agents to treat candidaemia and other forms of invasive candidiasis in human patients. If "time is of the essence" to reduce the mortality for these infections, the administration of appropriate antifungal therapy could be accelerated by the timely reporting of laboratory test results. In this study, we attempted to validate a MALDI-ToF mass spectrometry-based assay for the antifungal susceptibility testing (AFST) of the potentially multidrug-resistant pathogen Candida glabrata against anidulafungin and fluconazole. The practical applicability of the assay, reported here as MS-AFST, was assessed with a panel of clinical isolates that were selected to represent phenotypically and genotypically/molecularly susceptible or resistant strains. The data show the potential of our assay for rapid detection of antifungal resistance, although the MS-AFST assay performed at 3 h of the in vitro antifungal exposure failed to detect C. glabrata isolates with echinocandin resistance-associated FKS2 mutations. However, cell growth kinetics in the presence of anidulafungin revealed important cues about the in vitro fitness of C. glabrata isolates, which may lead to genotypic or phenotypic antifungal testing in clinical practice

    Effect of process conditions on the performance of a dual-reactor biodesulfurization process

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    The biotechnological gas desulfurization process under haloalkaline conditions is widely applied for removal of toxic H2S from sour gas streams. In this process H2S is biologically oxidized into elemental sulfur. Recently, the process has been extended with an anaerobic process step (dual-reactor line-up), increasing the selectivity for elemental sulfur (S8) from ~85–97% and decreasing the formation of (thio)sulfate. It was also found that biological sulfide uptake took place in the anaerobic bioreactor. In order to apply this process in industry, more insight is needed of the effect of the process conditions on the process performance. The effect of the process conditions HRT and sulfide concentration in the anaerobic bioreactor and pH on the overall product selectivities and on biological sulfide uptake in the anaerobic bioreactor were investigated. 7 experiments were performed in a pilot-scale biodesulfurization set-up. In all experiments, high selectivities (>95%) for S8 formation were obtained, except when the pH in the aerated bioreactor was increased from 8.5 to 9.1 (selectivity of 88%). Furthermore, biological sulfide uptake in the anaerobic bioreactor increased at higher sulfide concentrations and at higher pH. We hypothesize the biological sulfide uptake under anaerobic conditions is related to polysulfide formation. Our results increase the understanding how to control biological sulfide conversion in the dual-reactor biodesulfurization process

    Photobiont diversity in lichen symbioses from extreme environments

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    Fungal–algal relationships—both across evolutionary and ecological scales—are finely modulated by the presence of the symbionts in the environments and by the degree of selectivity and specificity that either symbiont develop reciprocally. In lichens, the green algal genus Trebouxia Puymaly is one of the most frequently recovered chlorobionts. Trebouxia species-level lineages have been recognized on the basis of their morphological and phylogenetic diversity, while their ecological preferences and distribution are still only partially unknown. We selected two cosmopolitan species complexes of lichen-forming fungi as reference models, i.e., Rhizoplaca melanophthalma and Tephromela atra, to investigate the diversity of their associated Trebouxia spp. in montane habitats across their distributional range worldwide. The greatest diversity of Trebouxia species-level lineages was recovered in the altitudinal range 1,000–2,500 m a.s.l. A total of 10 distinct Trebouxia species-level lineages were found to associate with either mycobiont, for which new photobionts are reported. One previously unrecognized Trebouxia species-level lineage was identified and is here provisionally named Trebouxia “A52.” Analyses of cell morphology and ultrastructure were performed on axenically isolated strains to fully characterize the new Trebouxia “A52” and three other previously recognized lineages, i.e., Trebouxia “A02,” T. vagua “A04,” and T. vagua “A10,” which were successfully isolated in culture during this study. The species-level diversity of Trebouxia associating with the two lichen-forming fungi in extreme habitats helps elucidate the evolutionary pathways that this lichen photobiont genus traversed to occupy varied climatic and vegetative regimes

    SIR-C/X-SAR data calibration and ground truth campaign over the NASA-CB1 test-site

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    During the Space Shuttle Endeavour mission in October 1994, a remote-sensing campaign was carried out with the objectives of both radiometric and polarimetric calibration and ground truth data acquisition of bare soils. This paper presents the results obtained in the experiment. Polarimetric cross-talk and channel imbalance values, as well as radiometric calibration parameters, have been found to be within the science requirements for SAR images. Regarding ground truth measurements, a wide spread in the height rms values and correlation lengths has been observed, which has motivated a critical revisiting of surface parameters descriptors

    Towards a Greener and Scalable Synthesis of Na2_{2}Ti6_{6}O13_{13} Nanorods and Their Application as Anodes in Batteries for Grid-Level Energy Storage

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    Grid applications require high power density (for frequency regulation, load leveling, and renewable energy integration), achievable by combining multiple batteries in a system without strict high capacity requirements. For these applications however, safety, cost efficiency, and the lifespan of electrode materials are crucial. Titanates, safe and longevous anode materials providing much lower energy density than graphite, are excellent candidates for this application. The innovative molten salt synthesis approach proposed in this work provides exceptionally pure Na2_{2}Ti6_{6}O13_{13} nanorods generated at 900–1100 °C in a yield ≄80 wt%. It is fast, cost‐efficient, and suitable for industrial upscaling. Electrochemical tests reveal stable performance providing capacities of ≈100 mA h g−1^{-1} (Li) and 40 mA h g−1^{-1} (Na). Increasing the synthesis temperature to 1100 °C leads to a capacity decrease, most likely resulting from 1) the morphology/volume change with the synthesis temperature and 2) distortion of the Na2_{2}Ti6_{6}O13_{13} tunnel structure indicated by electron energy‐loss and Raman spectroscopy. The suitability of pristine Na2_{2}Ti6_{6}O13_{13} as the anode for grid‐level energy storage systems has been proven a priori, without any performance‐boosting treatment, indicating considerable application potential especially due to the high yield and low cost of the synthesis route

    Identification of far-red light acclimation in an endolithic Chroococcidiopsis strain and associated genomic features: Implications for oxygenic photosynthesis on exoplanets

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    Deserts represent extreme habitats where photosynthetic life is restricted to the lithic niche. The ability of rock-inhabiting cyanobacteria to modify their photosynthetic apparatus and harvest far-red light (near-infrared) was investigated in 10 strains of the genus Chroococcidiopsis, previously isolated from diverse endolithic and hypolithic desert communities. The analysis of their growth capacity, photosynthetic pigments, and apcE2-gene presence revealed that only Chroococcidiopsis sp. CCMEE 010 was capable of far-red light photoacclimation (FaRLiP). A total of 15 FaRLiP genes were identified, encoding paralogous subunits of photosystem I, photosystem II, and the phycobilisome, along with three regulatory elements. CCMEE 010 is unique among known FaRLiP strains by undergoing this acclimation process with a significantly reduced cluster, which lacks major photosystem I paralogs psaA and psaB. The identification of an endolithic, extremotolerant cyanobacterium capable of FaRLiP not only contributes to our appreciation of this phenotype’s distribution in nature but also has implications for the possibility of oxygenic photosynthesis on exoplanets
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