Compared with mechanical fastening, adhesive bonding offers numerous advantages in the joining of pultruded glass fiber reinforced polymer (GFRP) sections. However, one critical issue associated with ...bonded joints is the assessment of their mechanical behavior considering bondline defects. This paper presents the results of an experimental investigation of the damage tolerance of adhesively bonded pultruded GFRP joints considering bondline defects. Double-strap specimens with and without bondline defects were prepared and tested in tension until failure. The location (five different locations in the bond length and width directions), size (10%, 20%, and 30% of the total bonded area in both the bond length and width directions), shape (triangular, rectangular, square, circular, and elliptical), and number (between 1 and 8) of defects within the bondline were considered as variable parameters. This paper reports and discusses the observed failure modes, load–displacement curves, and joint capacities, considering the effects of bondline defects. Interface debonding was observed in regions neighboring the bondline defects, and delamination was observed in other bonded areas. All joints exhibited a linear elastic load–displacement response with sudden and brittle failure, regardless of the presence of bondline defects. The observed capacity reduction of up to 33% could be significant if the defects were located at the edges of the bonded area. Defects of different shapes resulted in similar reductions in joint capacity (21%). Furthermore, the joint was found to be more sensitive to irregularly shaped (e.g., triangular) defects, and reducing the number of defects was more effective in mitigating the reduction in joint capacity than reducing the total defect area was.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Speaking involves coordination of multiple neuromotor systems, including respiration, phonation and articulation. Developing non-invasive imaging methods to study how the brain controls these systems ...is critical for understanding the neurobiology of speech production. Recent models and animal research suggest that regions beyond the primary motor cortex (M1) help orchestrate the neuromotor control needed for speaking, including cortical and sub-cortical regions. Using contrasts between speech conditions with controlled respiratory behavior, this fMRI study investigates articulatory gestures involving the tongue, lips and velum (i.e., alveolars versus bilabials, and nasals versus orals), and phonatory gestures (i.e., voiced versus whispered speech). Multivariate pattern analysis (MVPA) was used to decode articulatory gestures in M1, cerebellum and basal ganglia. Furthermore, apart from confirming the role of a mid-M1 region for phonation, we found that a dorsal M1 region, linked to respiratory control, showed significant differences for voiced compared to whispered speech despite matched lung volume observations. This region was also functionally connected to tongue and lip M1 seed regions, underlying its importance in the coordination of speech. Our study confirms and extends current knowledge regarding the neural mechanisms underlying neuromotor speech control, which hold promise to study neural dysfunctions involved in motor-speech disorders non-invasively.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
► Envelope design variables have large influence on the building energy performance. ► Early design requires simple tools to obtain building energy performance information. ► ERED is a new design ...indicator of energy performance for residential buildings. ► ERED was validated against detailed simulation results of 8000 residential buildings. ► Results show a strong correlation between ERED and simulated energy demand.
The architectural design variables which most influence the energy performance of a building are the envelope materials, shape and window areas. As these start to be defined in the early design stages, designers require simple tools to obtain information about the energy performance of the building for the design variations being considered at this phase. The shape factor is one of those tools, but it fails to correlate with energy demand in the presence of important solar gains. This paper presents a new design indicator of energy performance for residential buildings, the Envelope-Related Energy Demand (ERED), which aims to overcome the shortcomings of the shape factor while maintaining a reasonable simplicity of use. The inputs to ERED are areas of envelope elements (floor, walls, roofs and windows), U-values of envelope materials, solar heat gain coefficients (SHGC) of windows and site related parameters, concerning temperature and solar irradiation. ERED was validated against detailed simulation results of 8000 hypothetical residential buildings, varying in envelope shape, window areas and materials. Results show that there is a strong correlation between ERED and simulated energy demand. These results confirm the adequacy of ERED to assist design decisions in early stages of the design process.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
This paper investigates the effects of thermal cycles on the structural integrity of a pultruded Glass Fibre Reinforced Polymer (GFRP). Through a critical review of current literature alongside a ...comprehensive experimental campaign, the material’s response to cyclic thermal loading has been ascertained, defined by the rate of degradation of its physical, mechanical and visco-elastic properties. Matching sets of both dry and soaked samples conditioned in distilled water for 224days. Freeze–thaw cycling of both dry and soaked samples was conducted between 20°C and −10°C for a total of 300 cycles. Computed Tomography scanning (CT-scan) was undertaken to assess the microstructural physical changes throughout freeze–thaw cycling. After exposure, GFRP samples exhibited a minor decrease in glass transition temperature (Tg) which indicated minor structural degradation. Dry GFRP sample’s mechanical response exhibited negligible changes in both tensile and in-plane shear properties. However, as a result of the higher induced thermal stresses, soaked samples showed a significant degradation of their tensile and shear strengths. Yet, the soaked material’s stiffness remained largely unaffected due to the potential reversible nature of plasticization, which acts to increase the material’s molecular mobility when initially moisture-saturated, but is later recovered as the soaked samples lose moisture throughout freeze–thaw cycling.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Diversification by young, small firms Baptista, Rui; Karaöz, Murat; Leitão, João Correia
Small business economics,
06/2020, Volume:
55, Issue:
1
Journal Article
Peer reviewed
We investigate the determinants of young, small firm diversification by using longitudinal linked employer-employee data. We focus particularly on the role played by the sharing of managerial and ...qualified human resources, as well as market uncertainty and entry mistakes. We find that a small but significant proportion of young, small firms diversify in their first years. Firms with a greater proportion of managers and qualified human resources are more likely to diversify early, lending credence to the resource-based view of diversification. Firms entering volatile markets are more likely to diversify earlier as well, suggesting that entry mistakes and escape from uncertain, Schumpeterian environments also influence diversification. The inspection of survival patterns of diversified firms sheds further light on the importance of these two determinants of diversification.
A multi-criteria approach to the h-index Brandão, Luana Carneiro; Soares de Mello, João Carlos Correia Baptista
European journal of operational research,
07/2019, Volume:
276, Issue:
1
Journal Article
Peer reviewed
•We study the h-index in light of the multi-criteria fundamental axioms of coherence.•The number of publications and citations alone are not a coherent criteria family.•We propose a third criterion ...for the h-index: the distribution of citations.•The criteria family that forms the h-index becomes coherent with all three criteria.
The h-index was proposed in 2005, to objectively measure the impact and relevance of individuals' scientific output, based on their number of publications and citations. Since then, many works have studied the index's advantages and limitations, in various contexts and viewpoints. Still, we contribute to such a vast literature, by adopting a multi-criteria perspective to this matter. More precisely, we study the h-index in light of the fundamental axioms of coherence. We show that the number of publications and the number of total citations alone do not compose a coherent criteria family for the h-index, because it does not follow the axiom of exhaustivity. Thus, in this paper, we study examples from the literature to propose a suitable third criterion for the h-index, specifically, the form of the citation distribution among publications, which is less obvious than the other two. We verify that, with all three criteria, the criteria family that forms the h-index becomes coherent.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Fungal cells change shape in response to environmental stimuli, and these morphogenic transitions drive pathogenesis and niche adaptation. For example, dimorphic fungi switch between yeast and hyphae ...in response to changing temperature. The basidiomycete Cryptococcus neoformans undergoes an unusual morphogenetic transition in the host lung from haploid yeast to large, highly polyploid cells termed Titan cells. Titan cells influence fungal interaction with host cells, including through increased drug resistance, altered cell size, and altered Pathogen Associated Molecular Pattern exposure. Despite the important role these cells play in pathogenesis, understanding the environmental stimuli that drive the morphological transition, and the molecular mechanisms underlying their unique biology, has been hampered by the lack of a reproducible in vitro induction system. Here we demonstrate reproducible in vitro Titan cell induction in response to environmental stimuli consistent with the host lung. In vitro Titan cells exhibit all the properties of in vivo generated Titan cells, the current gold standard, including altered capsule, cell wall, size, high mother cell ploidy, and aneuploid progeny. We identify the bacterial peptidoglycan subunit Muramyl Dipeptide as a serum compound associated with shift in cell size and ploidy, and demonstrate the capacity of bronchial lavage fluid and bacterial co-culture to induce Titanisation. Additionally, we demonstrate the capacity of our assay to identify established (cAMP/PKA) and previously undescribed (USV101) regulators of Titanisation in vitro. Finally, we investigate the Titanisation capacity of clinical isolates and their impact on disease outcome. Together, these findings provide new insight into the environmental stimuli and molecular mechanisms underlying the yeast-to-Titan transition and establish an essential in vitro model for the future characterization of this important morphotype.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Background: Ca2+ signals, elicited by cues from the oocyte and female tract, regulate human sperm behavior.
Results: CatSper channel activation (flagellum) and Ca2+ store mobilization (neck) caused ...similar Ca2+i elevation but induced functionally different behaviors.
Conclusion: Sperm motility pattern is determined by the site of Ca2+ mobilization.
Significance: Selection of Ca2+ signaling components and/or regulation of their availability for activation controls human sperm behavior.
Ca2+i signaling regulates sperm motility, enabling switching between functionally different behaviors that the sperm must employ as it ascends the female tract and fertilizes the oocyte. We report that different behaviors in human sperm are recruited according to the Ca2+ signaling pathway used. Activation of CatSper (by raising pHi or stimulating with progesterone) caused sustained Ca2+i elevation but did not induce hyperactivation, the whiplash-like behavior required for progression along the oviduct and penetration of the zona pellucida. In contrast, penetration into methylcellulose (mimicking penetration into cervical mucus or cumulus matrix) was enhanced by activation of CatSper. NNC55-0396, which abolishes CatSper currents in human sperm, inhibited this effect. Treatment with 5 μm thimerosal to mobilize stored Ca2+ caused sustained Ca2+i elevation and induced strong, sustained hyperactivation that was completely insensitive to NNC55-0396. Thimerosal had no effect on penetration into methylcellulose. 4-Aminopyridine, a powerful modulator of sperm motility, both raised pHi and mobilized Ca2+ stored in sperm (and from microsomal membrane preparations). 4-Aminopyridine-induced hyperactivation even in cells suspended in Ca2+-depleted medium and also potentiated penetration into methylcellulose. The latter effect was sensitive to NNC55-039, but induction of hyperactivation was not. We conclude that these two components of the Ca2+i signaling apparatus have strikingly different effects on sperm motility. Furthermore, since stored Ca2+ at the sperm neck can be mobilized by Ca2+-induced Ca2+ release, we propose that CatSper activation can elicit functionally different behaviors according to the sensitivity of the Ca2+ store, which may be regulated by capacitation and NO from the cumulus.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Background: Several gastroenterology societies have created recommendations in order to reduce nonessential exposure to the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus. Our aim ...is to evaluate the national gastroenterologists’ perspective on the impact of COVID-19 and the impact of reorganization of a gastroenterology department during the COVID-19 pandemic. Methods: For the first purpose, an online survey was distributed to gastroenterologists nationwide. For the second purpose, the authors conducted an analysis of some endoscopic procedures performed at the Gastroenterology Department of the Centro Hospitalar Vila Nova de Gaia/Espinho (CHVNG/E) between March 16 and May 8 during the years 2019 and 2020. Results: Sixty-seven gastroenterologists answered our survey. Only 14.9% were residents and 86.6% worked in a hospital with COVID-19 patients, with 16.4% assigned to assist those patients. All of the departments suffered modifications. Ninety percent of the residents affirmed that their activity had changed. Ninety-four percent declared having nonessential endoscopic procedures postponed, and 85.1% maintained in-person medical visits, 88.1% were already having remote consultations, and 11.9% did not have any clinical visit. In our gastroenterology unit, the number of endoscopic procedures decreased by 73.1% from 2019 to 2020. In 2020, the proportion of urgent procedures was higher compared to 2019. Conclusion: The advent of COVID-19 has led to important changes in gastroenterology activities in Portugal, and national gastroenterology units are complying with the recommendations. Furthermore, Portuguese gastroenterologists believed that the decrease in endoscopic activity can compromise residents’ education and training. The gastroenterology department at CHVNG/E has shown a significant reduction in the number of endoscopic procedures.
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