20,168 research outputs found
Magnetic phase diagram and reentrant superconductivity in DyNi2B2C single crystals
No full textIn order to investigate the interaction between superconductivity and magnetic ordering resistivity, magnetisation measurements were performed on DyNi2B2C single crystals for T = 0.05-15 K and for B = 0-5 T in the crystallographic ab-plane. Measurements of the magnetisation with a torque cantilever magnetometer give strong evidence for metamagnetic states built of different ordered ferromagnetic domains. For B parallel to [100]. an anomalous large hysteresis effect of the metamagnetic transitions and also of the superconducting transitions were observed in the low-temperature range (T < 2 K). In some extreme cases, the metamagnetic state can be frozen after a field cycle sweeping up to 2 T and down to zero at 50 mK. In this case, superconductivity is totally suppressed. The superconducting state can be restored in two ways: Either with increasing temperature, or by applying a small field with the opposite field direction. (C) 2001 Elsevier Science B.V. All rights reserved
Sufficient spectral conditions for graphs being -edge-Hamiltonian or -Hamiltonian
No full textA graph is -edge-Hamiltonian if any collection of vertex-disjoint
paths with at most edges altogether belong to a Hamiltonian cycle in . A
graph is -Hamiltonian if for all with , the
subgraph induced by has a Hamiltonian cycle. These two
concepts are classical extensions for the usual Hamiltonian graphs. In this
paper, we present some spectral sufficient conditions for a graph to be
-edge-Hamiltonian and -Hamiltonian in terms of the adjacency spectral
radius as well as the signless Laplacian spectral radius. Our results could be
viewed as slight extensions of the recent theorems proved by Li and Ning
[Linear Multilinear Algebra 64 (2016)], Nikiforov [Czechoslovak Math. J. 66
(2016)] and Li, Liu and Peng [Linear Multilinear Algebra 66 (2018)]. Moreover,
we shall prove a stability result for graphs being -Hamiltonian, which could
be regarded as a complement of two recent results of F\"{u}redi, Kostochka and
Luo [Discrete Math. 340 (2017)] and [Discrete Math. 342 (2019)].Comment: 21 pages, 1 figure. Any comments and suggestions are welcome. E-mail
addresses: [email protected] (Yongtao Li), [email protected] (Yuejian Peng,
corresponding author). Linear and Multilinear Algebra, 202
Clearage of Territrems by Alkaline Hydrogen Peroxide:Isolation and Chorracterization of the Aromatic Moiety of Territrems
No full textTrypanosomes cause dysregulation of c-fos expression in the rat suprachiasmatic nucleus
No full textRats infected with the parasite Trypanosoma brucei brucei showed selective changes of c-fos expression in the suprachiasmatic nucleus of the hypothalamus (SCN) during spontaneous sleep (S) and wakefulness (W) under a basal 12 h/12 h light-dark (L-D) cycle. In the vast majority of W (D phase) control animals the SCN was devoid of cells displaying Fos-related immunopositivity, while Fos-like-immunoreactive (ir) neurones were detected in most S (L phase) control rats. In most infected animals, on the other hand, Fos-ir neurones were detected in the SCN during W, but not during the S period, with a significant difference between control and infected S rats. Thus, these data indicate that the basal c-fos expression in the SCN during the L-D and S-W cycles is considerably altered in experimental trypanosomiasis. This is the first observation of a selective change in the SCN in trypanosome-infected rat brains. Since the SCN plays an important role as a pace-maker for biological rhythms, this finding may provide a basis for understanding the pathogenesis behind endogenous rhythm dyregulation and changes in sleeping pattern in human trypanosomiasis (African sleeping sickness)
Molecular recognition with C-clamp porphyrins: Synthesis, structural, and complexation studies
No full textPosttranslational modification of serine to formylglycine in bacterial sulfatases - Recognition of the modification motif by the iron-sulfur protein AtsB
No full textMarquordt C, Fang QH, Will E, Peng JH, Figura von K, Dierks T. Posttranslational modification of serine to formylglycine in bacterial sulfatases - Recognition of the modification motif by the iron-sulfur protein AtsB. JOURNAL OF BIOLOGICAL CHEMISTRY. 2003;278(4):2212-2218.Calpha-formylglycine is the catalytic residue of sulfatases. Formylglycine is generated by posttranslational modification of a cysteine (pro- and eukaryotes) or serine (pro-karyotes) located in a conserved (C/S)XPXR motif. The modifying enzymes are unknown. AtsB, an iron-sulfur protein, is strictly required for modification of Se-72 in the periplasmic sulfatase AtsA of Klebsiella pneumoniae. Here we show W that AtsB is a cytosolic protein acting on newly synthesized serine-type sulfatases, (ii) that AtsB-mediated FGly formation is dependent on AtsA's signal peptide, and (iii) that the cytosolic cysteine-type sulfatase of Pseudomonas aeruginosa can be converted into a substrate of AtsB if the cysteine is substituted by serine and a signal peptide is added. Thus, formylglycine formation in serine-type sulfatases depends both on AtsB and on the presence of a signal peptide, and AtsB can act on sulfatases of other species. AtsB physically interacts with AtsA in a Ser(72)-dependent manner, as shown in yeast two-hybrid and GST pulldown experiments. This strongly suggests that AtsB is the serine-modifying enzyme and that AtsB relies on a cytosolic function of the sulfatase's signal peptide
Unsteady disturbances in a swept wing boundary layer due to plasma forcing
No full textThis work investigates the response of a transitional boundary layer to spanwise-invariant dielectric barrier discharge plasma actuator (PA) forcing on a 45 ° swept wing at a chord Reynolds number of 2.17 × 10 6. Two important parameters of the PA operation are scrutinized, namely, the forcing frequency and the streamwise location of forcing. An array of passive discrete roughness elements is installed near the leading edge to promote and condition a set of critical stationary crossflow (CF) instability modes. Numerical solutions of the boundary layer equations and linear stability theory are used in combination with the experimental pressure distribution to provide predictions of critical stationary and traveling CF instabilities. The laminar-turbulent transition front is visualized and quantified by means of infrared thermography. Measurements of velocity fields are performed using hotwire anemometry scans at specific chordwise locations. The results demonstrate the inherent introduction of unsteady velocity disturbances by the plasma forcing. It is shown that, depending on actuator frequency and location, these disturbances can evolve into typical CF instabilities. Positive traveling low-frequency type III modes are generally amplified by PA in all tested cases, while the occurrence of negative traveling high-frequency type I secondary modes is favored when PA is operating at high frequency and at relatively downstream locations, with respect to the leading edge. </p
Digital resilience in the internationalization of small and medium companies: how does it work?
No full textPurpose Digital technologies over time are becoming increasingly pervasive and relatively affordable, finding a large diffusion in Small and Medium Enterprises (SMEs) also for internationalization purposes. However, less is known about the specific mechanisms by which this can be achieved. Specifically, we focus on how SMEs can face the international environment, leveraging digital technologies and thanks to their intellectual capital (IC).Design/methodology/approach We analyze the relationship between digital technologies and the internationalization of SMEs, exploring the mediating role of IC in its three dimensions: human, relational and innovation capital, and assessing the possible moderating effects posed by international institutional conditions, specifically the Sino-US trade frictions. The relationships are tested using a sample of companies listed on China's A-share Growth Enterprise Market (GEM) from 2010 to 2021.Findings Digital technologies help to internationalize SMEs. However, this positive relationship is affected (mediated) by the presence of an already consolidated IC. In addition, the institutional conditions of the international market, such as the Sino-US trade friction, moderate the components of IC differently. Specifically, the overall mediating effect of human and relational capital is boosted, while this does not happen for innovation capital.Originality/value First, this study contributes to the literature on organizational resilience, especially digital resilience, confirming its validity in the context of internationalization and, in particular, those processes adopted by SMEs. Second, we clarify the mechanisms through which digital technologies exert their impact on the process of internationalization and in particular the prominent necessity of having IC. Third, our conclusions enrich the understanding of how IC components react to turbulence in international markets
Dysregulation of photic induction of Fos-related protein in the biological clock during experimental trypanosomiasis
No full textThe mammalian suprachiasmatic nuclei of the hypothalamus (SCN) serve as pacemaker for circadian rhythms and the immediate-early gene c-fos is known to be induced by photic stimulation in the SCN of rodents. We studied the induction of Fos-related protein following a light pulse in rats infected with Trypanosoma brucei. This parasite causes in humans African sleeping sickness, a neuropsychiatric syndrome that involves changes of endogenous biological rhythms. Fos-like immunoreactivity after photic stimulation was dramatically reduced in the SCN of trypanosome- infected rats during the subjective night. These findings indicate that the photic entrainment of the biological clock may be altered during the infection
Crossflow instabilities under plasma actuation: Design, commissioning and preliminary results of a new experimental facility
No full textPlasma-based flow control poses a simple and robust technique for transition delay on swept wings. However, a clear understanding of how plasma actuators affect crossflow instabilities is necessary to develop and mature crossflow control based on plasma actuators. In this paper, the design of a new swept wing model optimised for the study of crossflow receptivity and stability under plasma actuator is described in detail. First, a 2D wing shape is designed, to match the nearing leading edge pressure distribution of a reference high-Reynolds number swept wing model (M3J) which has been used extensively in past investigations. The aerodynamic performance of this new shape is investigated using CFD simulations and the results show a good agreement for the pressure coefficient. In manufacturing design, the wing model features provisions to accept plasma actuators, such as non-conductive material as well as an appropriately designed recess for the actuator assembly. The new model in conjunction with a recently refurbished low turbulence windtunnel facility are characterized in a preliminary experiment. The uniformity and quality of the flow is identified using pressure measurements and the results confirm the new model achieved near-invariant spanwise conditions until 40% of the chord. Infrared thermography is used to capture the surface footprint of stationary primary crossflow vortices. Clear formations of stationary vortices created by discrete roughness are captured and no visible transition is observed. Finally, the effects of plasma actuation on crossflow instabilities are inspected by Infrared Thermography and PIV scanning. The results validate the prediction of Linear Stability Theory with respect to the most unstable stationary mode and traveling mode. The appearance of secondary crossflow instabilities is observed at relatively upstream chord locations even without transition detected. The outcome positively confirms the ability of this new model to reproduce receptivity and initial growth of crossflow instabilities of the reference model (M3J) under plasma actuation.Virtual/online event due to COVID-19AerodynamicsWind Energ
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