Incentive Mechanisms for Internet Congestion Management: Fixed-Budget Rebate versus Time-of-Day Pricing

Mobile data traffic has been steadily rising in the past years. This has generated a significant interest in the deployment of incentive mechanisms to reduce peak-time congestion. Typically, the design of these mechanisms requires information about user demand and sensitivity to prices. Such information is naturally imperfect. In this paper, we propose a \emph{fixed-budget rebate mechanism} that gives each user a reward proportional to his percentage contribution to the aggregate reduction in peak time demand. For comparison, we also study a time-of-day pricing mechanism that gives each user a fixed reward per unit reduction of his peak-time demand. To evaluate the two mechanisms, we introduce a game-theoretic model that captures the \emph{public good} nature of decongestion. For each mechanism, we demonstrate that the socially optimal level of decongestion is achievable for a specific choice of the mechanism's parameter. We then investigate how imperfect information about user demand affects the mechanisms' effectiveness. From our results, the fixed-budget rebate pricing is more robust when the users' sensitivity to congestion is "sufficiently" convex. This feature of the fixed-budget rebate mechanism is attractive for many situations of interest and is driven by its closed-loop property, i.e., the unit reward decreases as the peak-time demand decreases.Comment: To appear in IEEE/ACM Transactions on Networkin

Extremal and maximal normal abelian subgroups of a maximal unipotent subgroup in groups of Lie type

AbstractWe describe all maximal abelian normal subgroups in the unipotent radical U of a Borel subgroup in a group of Lie type G over a field K. This gives a new description of the extremal subgroups in U which were studied by C. Parker and P. Rowley. For a finite field K, we prove that either each large abelian subgroup in U is G-conjugate to a normal subgroup in U or G is of certain exceptional Lie type

Propeller outflows from an MRI disc

We present the results of axisymmetric simulations of MRI-driven accretion onto a rapidly rotating, magnetized star accreting in the propeller regime. The stellar magnetosphere corotates with the star, forming a centrifugal barrier at the disc-magnetosphere boundary which inhibits matter accretion onto the star. Instead, the disc matter accumulates at the disc-magnetosphere interface and slowly diffuses into the inner magnetosphere where it picks up angular momentum and is quickly ejected from the system as an outflow. Due to the interaction of the matter with the magnetosphere, this wind is discontinuous and is launched as discrete plasmoids. If the ejection rate is lower than the disc accretion rate, the matter accumulates at the disc-magnetosphere boundary faster than it can be ejected. In this case, accretion onto the star proceeds through the episodic accretion instability in which episodes of matter accumulation are followed by simultaneous accretion and ejection. During the accretion phase of this instability in which matter flows onto the star in funnel streams, we observe a corresponding rise in the outflow rate. Both the accretion and ejection processes observed in our simulations are highly non-stationary. The stars undergo strong spin-down due to the coupling of the stellar field with the disc and corona and we measure the spin-down timescales of around 1 Myr for a typical CTTS in the propeller regime.Comment: 13 pages, 10 figures, submitted to MNRA

Разработка методического инструмента повышения конкурентоспособности международной деятельности университета

The improvement of Russian higher education competitiveness is a strategic task for the country socio-economic development. The higher school trains experts who will have to solve the complex tasks faced by the country economy, and provide a technological breakthrough. At that it should be noted that the modern graduate should have skills in the global economy. The implementation of measures improving the competitiveness of Russian higher education is faced with a number of restrictions caused by the global economic development. One of the main limitations is state funding reduction for universities, which forces them to seek new sources of resources, including the external market. This leads to increased competition between universities for applicants. It should be noted that competition is not limited only to the national market, it acquires an international character. In developed economies, higher education is one of the sources of export earnings. Besides, foreign countries recruit qualified labor through international educational projects. One of the tools to improve the competitiveness of university is its international activity. On this basis, it follows that the development of methodological tools for international activity management in a higher education institution is an urgent task today.La mejora de la competitividad de la educación superior rusa es una tarea estratégica para el desarrollo socioeconómico del país. La escuela superior capacita a expertos que tendrán que resolver las complejas tareas que enfrenta la economía del país y proporcionar un avance tecnológico. En eso debe tenerse en cuenta que el graduado moderno debe tener habilidades en la economía global. La implementación de medidas que mejoran la competitividad de la educación superior rusa se enfrenta a una serie de restricciones causadas por el desarrollo económico global. Una de las principales limitaciones es la reducción de fondos estatales para las universidades, lo que las obliga a buscar nuevas fuentes de recursos, incluido el mercado externo. Esto lleva a una mayor competencia entre las universidades por los solicitantes. Cabe señalar que la competencia no se limita solo al mercado nacional, sino que adquiere un carácter internacional. En las economías desarrolladas, la educación superior es una de las fuentes de ingresos de exportación. Además, los países extranjeros reclutan mano de obra calificada a través de proyectos educativos internacionales. Una de las herramientas para mejorar la competitividad de la universidad es su actividad internacional. Sobre esta base, se deduce que el desarrollo de herramientas metodológicas para la gestión de la actividad internacional en una institución de educación superior es una tarea urgente hoy en día.Повышение конкурентоспособности российского высшего образования является стратегической задачей социально-экономического развития страны. Высшая школа готовит специалистов, которым предстоит решать сложные задачи, стоящие перед экономикой страны, и обеспечивать технологический прорыв. При этом следует отметить, что современный выпускник должен обладать навыками в мировой экономике. Реализация мер по повышению конкурентоспособности российского высшего образования сталкивается с рядом ограничений, обусловленных глобальным экономическим развитием. Одним из основных ограничений является сокращение государственного финансирования университетов, что заставляет их искать новые источники ресурсов, в том числе на внешнем рынке. Это приводит к усилению конкуренции между университетами за абитуриентов. Следует отметить, что конкуренция не ограничивается только национальным рынком, она приобретает международный характер. В развитых экономиках высшее образование является одним из источников экспортных поступлений. Кроме того, зарубежные страны привлекают квалифицированную рабочую силу в рамках международных образовательных проектов. Одним из инструментов повышения конкурентоспособности университета является его международная деятельность. Исходя из этого, из этого следует, что разработка методологических инструментов управления международной деятельностью в вузе является актуальной задачей на сегодняшний день

Opening a nodal gap by fluctuating spin-density-wave in lightly doped La2−x_{2-x}Srx_xCuO4_4

We investigate whether the spin or charge degrees of freedom are responsible for the nodal gap in underdoped cuprates by performing inelastic neutron scattering and x-ray diffraction measurements on La$_{2-x}$Sr$_x$CuO$_4$, which is on the edge of the antiferromagnetic phase. We found that fluctuating incommensurate spin-density-wave (SDW) with a the bottom part of an hourglass dispersion exists even in this magnetic sample. The strongest component of these fluctuations diminishes at the same temperature where the nodal gap opens. X-ray scattering measurements on the same crystal show no signature of charge-density-wave (CDW). Therefore, we suggest that the nodal gap in the electronic band of this cuprate opens due to fluctuating SDW with no contribution from CDW

Sequence variation in CYP51A from the Y strain of Trypanosoma cruzi alters its sensitivity to inhibition

CYP51 (sterol 14α-demethylase) is an efficient target for clinical and agricultural antifungals and an emerging target for treatment of Chagas disease, the infection that is caused by multiple strains of a protozoan pathogen Trypanosoma cruzi. Here, we analyze CYP51A from the Y strain T. cruzi. In this protein, proline 355, a residue highly conserved across the CYP51 family, is replaced with serine. The purified enzyme retains its catalytic activity, yet has been found less susceptible to inhibition. These biochemical data are consistent with cellular experiments, both in insect and human stages of the pathogen. Comparative structural analysis of CYP51 complexes with VNI and two derivatives suggests that broad-spectrum CYP51 inhibitors are likely to be preferable as antichagasic drug candidates.Fil: Cherkesova, Tatiana S.. National Academy of Sciences of Belarus. Institute of Bioorganic Chemistry; BielorrusiaFil: Hargrove, Tatiana Y.. Vanderbilt University; Estados UnidosFil: Vanrell, Maria Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Histología y Embriología de Mendoza Dr. Mario H. Burgos. Universidad Nacional de Cuyo. Facultad de Cienicas Médicas. Instituto de Histología y Embriología de Mendoza Dr. Mario H. Burgos; ArgentinaFil: Ges, Igor. Vanderbilt University; Estados UnidosFil: Usanov, Sergey A.. National Academy of Sciences of Belarus. Institute of Bioorganic Chemistry; BielorrusiaFil: Romano, Patricia Silvia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Histología y Embriología de Mendoza Dr. Mario H. Burgos. Universidad Nacional de Cuyo. Facultad de Cienicas Médicas. Instituto de Histología y Embriología de Mendoza Dr. Mario H. Burgos; ArgentinaFil: Lepesheva, Galina I.. Vanderbilt University; Estados Unido