114,201 research outputs found
Asymptotic properties of ground states of scalar field equations with a vanishing parameter
No full textWe study the leading order behaviour of positive solutions of the equation-Delta u + epsilon u - vertical bar u vertical bar(p-2) u + vertical bar u vertical bar(q-2) u = 0; x is an element of R-Nwhere N >= 3, q > p > 2 and epsilon > 0 is a small parameter. We give a complete characterization of all possible asymptotic regimes as a function of p, q and N. The behaviour of solutions depends on whether p is less than, equal to or greater than the critical Sobolev exponent 2* = 2N/N-2. For p < 2* the solution asymptotically coincides with the solution of the equation in which the last term is absent. For p > 2* the solution asymptotically coincides with the solution of the equation with epsilon = 0. In the most delicate case p = 2* the asymptotic behaviour of the solutions is given by a particular solution of the critical Emden-Fowler equation, whose choice depends on epsilon in a nontrivial way
Vassili Ivanovich Moroz: An Appreciation
No full textThe 2005 LPSC special session, OMEGA At Mars, is dedicated to the work and memory of V. I. Moroz, in recognition of his pioneering studies in the characterization of planetary bodies with remotely sensed data, and his special interest in, and contributions to, the study of Mars
In situ analysis of pH gradients in mosquito larvae using non-invasive, self-referencing, pH-sensitive microelectrodes
No full textThe alkaline environment, pH approximately 11, in the anterior midgut lumen of mosquito larvae is essential for normal nutrition and development. The mechanism of alkalization is, however, unknown. Although evidence from immunohistochemistry, electron microscopy and electrophysiology suggests that a V-ATPase is present in the basal membranes of the epithelial cells, its physiological role in the alkalization process has not been demonstrated. To investigate a possible role of the V-ATPase in lumen alkalization, pH gradients emanating from the hemolymph side of the midgut in semi-intact mosquito larvae were measured using non-invasive, self-referencing, ion-selective microelectrodes (SERIS). Large H+ concentration gradients, with highest concentrations close to the basal membrane (outward [H+] gradients), were found in the anterior midgut, whereas much smaller gradients, with concentrations lowest close to this membrane (inward [H+] gradients), were found in the gastric caeca and posterior midgut. Similar region-specific pH gradients, with consistent anterior-to-posterior profiles, were observed in individuals of two Aedes species, Aedes aegypti from semi-tropical Florida and Aedes canadensis from north-temperate Massachusetts. The gradients remained in a steady state for up to 6 h, the maximum duration of the recordings. Bafilomycin A1 (10(-5), 10(-7 )mol x l(-1)) on the hemolymph side greatly diminished the [H+] gradients in the anterior midgut but had no effect on the gradients in the gastric caecum and posterior midgut. These physiological data are consistent with the previous findings noted above. Together, they support the hypothesis that a basal, electrogenic H+ V-ATPase energizes luminal alkalization in the anterior midgut of larval mosquitoes
Digital literacy of elementary school children in Slovenia
No full textV učnih načrtih osnovnih šol so predvideni cilji in vsebine, ki predvidevajo digitalno opismenjevanje. Diplomsko delo proučuje različne načine razvijanja digitalne pismenosti osnovnošolskih otrok v Sloveniji in kako se učitelji spopadajo z umeščanjem informacijsko-komunikacijskih tehnologij v obvezne predmete. Na podlagi fokusnih skupin in poglobljenih intervjujev je bilo ugotovljeno, da je znanje na tem področju med učenci precej heterogeno in da uporabljajo različne vire za razvijanje digitalnih kompetenc. Hkrati poučevanje in vpeljevanje informacijsko-komunikacijskih tehnologij predstavlja izziv učiteljem, ki se po lastni presoji držijo smernic in priporočil. Ugotovljeno je bilo tudi, da se vse vsebine na vseh šolah ne izvajajo, kar nakazuje potrebo po smiselnem preoblikovanju vpeljevanja omenjenih vsebin v splošne predmete.In the curricula of elementary schools, goals and contents are designed to include digital literacy. The bachelor’s thesis examines different ways of developing the digital literacy of elementary school children in Slovenia and how teachers cope with the placement of information and communication technologies in compulsory subjects. Based on focus groups and in-depth interviews, it was established that knowledge in this area is quite heterogeneous among students and they use different resources to develop digital competences. At the same time, the teaching and introduction of information and communication technologies presents a challenge to teachers who, at their discretion, adhere to guidelines and recommendations. It was also established that not all subjects are implemented in all schools, which indicates the need for meaningful transformation of the introduction of the aforementioned subjects into general subjects
Groundstate asymptotics for a class of singularly perturbed p-Laplacian problems in RN
No full textWe study the asymptotic behaviour of positive groundstate solutions to the quasilinear elliptic equation [Figure not available: see fulltext.]where 1 < p< N, p< q< l< + ∞ and ε> 0 is a small parameter. For ε→ 0 , we give a characterization of asymptotic regimes as a function of the parameters q, l and N. In particular, we show that the behaviour of the groundstates is sensitive to whether q is less than, equal to, or greater than the critical Sobolev exponent p∗:=pNN-p
The impact of the COVID-19 epidemic on online fraud
No full textEpidemija covida-19 je močno vplivala na digitalno vedenje uporabnikov interneta in spodbudila razmah uporabe spletnih storitev. Zaradi povečane prisotnosti v digitalnem okolju so uporabniki postali bolj izpostavljeni spletnim prevaram, ki so v času epidemije postale ena izmed najpogostejših oblik kibernetske kriminalitete. Spletne goljufije se pogosto izvajajo prek lažnih elektronskih sporočil, lažnih spletnih strani, družbenih omrežij in drugih kanalov, ki omogočajo zlorabo zaupanja uporabnikov.
Najpogostejše oblike spletnih prevar vključujejo krajo identitete, spletno ribarjenje (angl. phishing), direktorsko prevaro, poneverbo računov in finančne prevare, romantično goljufijo, goljufije na družbenih omrežjih in goljufijo s kriptovalutami. Prevaranti izkoriščajo aktualne družbene okoliščine, čustveno ranljivost žrtev in pomanjkanje znanja o kibernetski varnosti. Razvoj umetne inteligence in dostopnost naprednih orodij kriminalcem omogočata vse bolj prepričljive oblike manipulacije.
Učinkovito preprečevanje spletnih goljufij temelji na kombinaciji pravnega urejanja, tehnoloških rešitev in sistematičnega ozaveščanja uporabnikov. Ključno vlogo pri zmanjševanju kibernetskih tveganj imajo izobraževanje, redno spremljanje tveganj ter sodelovanje med institucijami in javnostjo.The COVID-19 pandemic significantly influenced the digital behavior of internet users and accelerated the adoption of online services. Due to increased presence in the digital environment, users became more exposed to online fraud, which during the pandemic emerged as one of the most common forms of cybercrime. Online scams are often carried out through fake emails, fraudulent websites, social media platforms, and other channels that enable the exploitation of user trust.
The most common forms of online fraud include identity theft, phishing, CEO fraud, invoice fraud and financial scams, romance scams, social media fraud, and cryptocurrency scams. Fraudsters take advantage of current social conditions, victims’ emotional vulnerability, and a lack of cybersecurity awareness. The development of artificial intelligence and the availability of advanced tools allow criminals to carry out increasingly convincing manipulations.
Effective prevention of online fraud relies on a combination of legal regulation, technological solutions, and systematic user awareness. Education, regular risk monitoring, and cooperation between institutions and the public play a crucial role in reducing cyber risks
Groundstates and radial solutions to nonlinear Schrödinger–Poisson–Slater equations at the critical frequency
No full textWe study the nonlocal Schrödinger–Poisson–Slater type equation -Δu+(Iα ∗ |u|p)|u|p-2u=|u|q-2u in RN,where N∈ N, p> 1 , q> 1 and Iα is the Riesz potential of order α∈ (0 , N). We introduce and study the Coulomb–Sobolev function space which is natural for the energy functional of the problem and we establish a family of associated optimal interpolation inequalities. We prove existence of optimizers for the inequalities, which implies the existence of solutions to the equation for a certain range of the parameters. We also study regularity and some qualitative properties of solutions. Finally, we derive radial Strauss type estimates and use them to prove the existence of radial solutions to the equation in a range of parameters which is in general wider than the range of existence parameters obtained via interpolation inequalities
New copper(II) 1D polymer containing dimethyl(phenylsulfonyl)amidophosphate: Synthesis, crystal structure and magnetic properties
No full textThe reaction of sodium dimethyl(phenylsulfonyl)amidophosphate NaL (HL=C(6)H(5)SO(2)NHP(O)(OCH(3))(2)) with Cu(NO(3))(2) center dot 6H(2)O and o-bpe (1,2-bis(pyridine-2-yl)ethane) in appropriate ratios, afford the formation of 1D coordination polymer [Cu(L)(2) center dot o-bpe](n) in good yield. The crystal structures of HL (1) and [Cu(L)(2) center dot o-bpe](n) (2) are reported. In the crystal package the molecules of 1 are linked by intermolecular hydrogen bonds formed by the phosphoryl oxygen atoms which serve as acceptors and nitrogen atoms of amide groups as donors. The crystal structure of 2 indicates the presence of unsaturated Cu(L)(2) unit bridged by o-bpe ligand in the one-dimensional polymeric chain. The Cu(II) atoms have distorted 4 + 2 octahedral CuO(4)N(2) environment formed by the oxygen atoms belonging to the sulfonyl and phosphoryl groups of two deprotonated chelate ligands and nitrogen atoms of the bridging o-bpe ligands. The magnetic study of 2 has revealed the presence of a weak intrachain antiferromagnetic exchange interaction between copper ions. (C) 2009 Elsevier Ltd. All rights reserved.Fundamental Researches State Fund of Ukraine [F25/193 - 2008
Existence and concentration for nonlinear Schrodinger equations with fast decaying potentials
No full textThe existence of positive solutions to
-epsilon(2) Delta u + Vu = u(p) in R-N,
is proved for small epsilon, where N >= 3, V is a nonnegative continuous potential which has a positive local minimum, and N/N-2 < p < N+2/N-2 . No restriction is imposed on the rate of decay of V; this includes in particular the case where V is compactly supported. To cite this article: V. Moroz, J. Van Schaftingen, C. R. Acad. Sci. Paris, Ser. I 347 (2009). (c) 2009 Academie des sciences. Published by Elsevier Masson SAS. All rights reserved
Orbital-free density functional theory of out-of-plane charge screening in graphene.
No full textWe propose a density functional theory of Thomas-Fermi-Dirac-von Weizsacker type to describe the response of a single layer of graphene resting on a dielectric substrate to a point charge or a collection of charges some distance away from the layer. We formulate a variational setting in which the proposed energy functional admits minimizers, both in the case of free graphene layers and under back-gating. We further provide conditions under which those minimizers are unique and correspond to configurations consisting of inhomogeneous density profiles of charge carrier of only one type. The associated Euler-Lagrange equation for the charge density is also obtained, and uniqueness, regularity and decay of the minimizers are proved under general conditions. In addition, a bifurcation from zero to nonzero response at a finite threshold value of the external charge is proved
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