7,755 research outputs found
Critical Galton-Watson processes: The maximum of total progenies within a large window
Consider a critical Galton-Watson process Z={Z_n: n=0,1,...} of index
1+alpha, alpha in (0,1]. Let S_k(j) denote the sum of the Z_n with n in the
window [k,...,k+j), and M_m(j) the maximum of the S_k with k moving in [0,m-j].
We describe the asymptotic behavior of the expectation EM_m(j) if the window
width j=j_m is such that j/m converges in [0,1] as m tends to infinity. This
will be achieved via establishing the asymptotic behavior of the tail
probabilities of M_{infinity}(j).Comment: 28 page
Home-Based Parent-Child Therapy in Low-Income African American, Caucasian, and Latino Families: A Comparative Examination of Treatment Outcomes
This study examined parent and child treatment outcomes for a home-based Parent-Child Therapy (PCT) program for 66 children from families living in poverty. African American, Caucasian, and Latino families were examined to determine if an evidence-based program would produce similar results across different ethnic groups. The results showed that caregivers across the three ethnic groups reported improved child challenging behavior, increased positive parent-child interactions, improved parental expectations, higher levels of nurturing, and less reliance on verbal and corporal punishment as a form of discipline. Practical implications for these results are discussed
On the Importance of Displacement History in Soft-Body Contact Models
Two approaches are commonly used for handling frictional contact within the framework of the discrete element method (DEM). One relies on the complementarity method (CM) to enforce a nonpenetration condition and the Coulomb dry-friction model at the interface between two bodies in mutual contact. The second approach, called the penalty method (PM), invokes an elasticity argument to produce a frictional contact force that factors in the local deformation and relative motion of the bodies in contact. We give a brief presentation of a DEM-PM contact model that includes multi-time-step tangential contact displacement history. We show that its implementation in an open-source simulation capability called Chrono is capable of accurately reproducing results from physical tests typical of the field of geomechanics, i.e., direct shear tests on a monodisperse material. Keeping track of the tangential contact displacement history emerges as a key element of the model. We show that identical simulations using contact models that include either no tangential contact displacement history or only single-time-step tangential contact displacement history are unable to accurately model the direct shear test
Time Slot Management in Attended Home Delivery
Many e-tailers providing attended home delivery, especially e-grocers, offer narrow delivery time slots to ensure satisfactory customer service. The choice of delivery time slots has to balance marketing and operational considerations, which results in a complex planning problem. We study the problem of selecting the set of time slots to offer in each of the zip codes in a service region. The selection needs to facilitate cost-effective delivery routes, but also needs to ensure an acceptable level of service to the customer. We present two fully-automated approaches that are capable of producing high-quality delivery time slot offerings in a reasonable amount of time. Computational experiments reveal the value of these approaches and the impact of the environment on the underlying trade-offs.integer programming;vehicle routing;continuous approximation;e-grocery;home delivery;time slots
High Power Semiconductor Devices and Solid State Switches for Pulsed Discharge Applications
Based on long term experience, collected mainly with military applications like Rail Guns and Active Armour, a range of optimized semiconductor devices for pulsed applications was developed by ABB Switzerland Ltd and described in this presentation. The presented devices are optimized for pulsed discharge and fit very well for switching the short but high electrical power demand used for magnetic forming. Devices are available in different versions with silicon wafer diameters up to 120 mm and blocking voltages of over 6500V. Because of the different application requirements a differentiation is made in device technology. Depending on the discharge circuit, devices for low, medium, or high di/dt can be selected and the difference in advantages and disadvantages between both technologies will be described. To minimize the inductance between switching device and freewheeling diode, ABB can integrate this diode monolithic on the switching wafer. These so called reverse conducting devices are very common for magnetic forming applications. Thyristor structures are commercially available up to 8500V with 120 mm silicon wafers and GTO-like structures are available up to 4500V with 91 mm silicon wafers. For higher voltages or higher currents a combination of devices in series and/or parallel connection is required. The presentation will also describe the evolution of complete discharge switching modules in the range of 10kV / 50 kJ, a large discharge system of 21kV / 200kA, and a newly designed high current switch in the range of 15kV / 3MJ. The solid state switch solutions offered today and those shown in the presentation are based on a standard platform of components existing already for several years. For reliability reasons it is of great importance that the switch assemblies for high current pulsed applications are designed in cooperation with the device manufacturer who has in-depth knowledge of the switching behavior of the semiconductor components under pulsed conditions. The advantage of a complete switch assembly is that the whole unit can be tested under application conditions. ABB has a test capability up to 65 kV and 85 kJ stored energy
Fractal Conductance Fluctuations of Classical Origin
In mesoscopic systems conductance fluctuations are a sensitive probe of
electron dynamics and chaotic phenomena. We show that the conductance of a
purely classical chaotic system with either fully chaotic or mixed phase space
generically exhibits fractal conductance fluctuations unrelated to quantum
interference. This might explain the unexpected dependence of the fractal
dimension of the conductance curves on the (quantum) phase breaking length
observed in experiments on semiconductor quantum dots.Comment: 5 pages, 4 figures, to appear in PR
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Framing and Foreign Policy—Israel’s Response to the Arab Uprisings
The eruption of the 2010 Arab uprisings has generated a great deal of academic scholarship. However, the foreign policy of Israel, a key power in the Middle East, amid the Arab uprisings, has received limited attention. Furthermore, as we demonstrate, the conventional wisdom purported by the current debate, which is that Israel adopted a “defensive, non-idealist” realist foreign policy posture (Magen 2015, 114) in the wake of the Arab uprisings, is wrong. Rather, utilizing an innovative approach linking foreign policy analysis (FPA) and the literature on framing, we demonstrate that Israel adopted a foreign policy stance of entrenchment. This posture is predicated on peace for peace not territory, reinforcing Israel's military capabilities, and granting limited autonomy to the Palestinians under Israeli occupation. Thus, the article demonstrates how framing can usefully be operationalized to uncover how binary discourse does not merely reflect foreign policy but is, in fact, constitutive of it. We demonstrate that diagnostic and prognostic frames helped to create a direct connection between the images held by a leader, his/her worldview, ideas, perceptions and misperceptions, and foreign policy actions. These frames constituted action-oriented sets of beliefs and meaning that inspired and legitimated certain foreign policy options and instruments while restricting others
Statistical evidence that honeybees competitively reduced wild bee abundance in the Munich Botanic Garden in 2020 compared to 2019
In a commentary on our paper (Renner et al., Oecologia 195:825-831, 2021), Harder and Miksha lay out why they think that our finding of higher honeybee abundances reducing wild bee abundances in an urban botanical garden is not statistically supported. Here, we explain the statistical test provided in our paper, which took advantage of a natural experiment offered by 2019 being a poorer year for bee keeping than 2020
Multi-scale clustering for a non-Markovian spatial branching process
Consider a system of particles which move in R^d according to a symmetric alpha-stable motion, have a lifetime distribution of finite mean, and branch with an offspring law of index 1+beta. In case of the critical dimension d=alpha/beta, the phenomenon of multi-scale clustering occurs. This is expressed in an fdd scaling limit theorem, where initially we start with an increasing localized population or with an increasing homogeneous Poissonian population. The limit state is uniform, but its intensity varies in line with the scaling index according to a continuous-state branching process of index 1+beta. Our result generalizes the case alpha=2 of Brownian particles of Klenke (1998), where pde methods had been used which are not available in the present setting
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