Do About Half the Top Quarks at FNAL Come From Gluino Decays?

We argue that it is possible to make a consistent picture of FNAL data including the production and decay of gluinos and squarks. The additional cross section is several pb, about the size of that for Standard Model (SM) top quark pair production. If the stop squark mass is small enough, about half of the top quarks decay to stop squarks, and the loss of SM top quark pair production rate is compensated by the supersymmetric processes. This behavior is consistent with the reported top quark decay rates in various modes and other aspects of the data, and suggests several other possible decay signatures. This picture can be tested easily with more data, perhaps even with the data in hand, and demonstrates the potential power of a hadron collider to determine supersymmetric parameters. It also has implications for the top mass measurement and the interpretation of the LEP $R_b$ excess.Comment: 18 pages, including 4 Postscript figures, uses epsf.tex, also available at http://www.hep.anl.gov/theory/mrenna

Exact solutions for the KdV–mKdV equation with time-dependent coefficients using the modified functional variable method

In this article, the functional variable method (fvm for short) is introduced to establish new exact travelling solutions of the combined KdV–mKdV equation. The technique of the homogeneous balance method is used in second stage to handle the appropriated solutions. We show that, the method is straightforward and concise for several kinds of nonlinear problems. Many new exact travelling wave solutions are successfully obtained

Stable bipedal walking with foot rotation through direct regulation of the zero moment point

Consider a biped evolving in the sagittal plane. The unexpected rotation of the supporting foot can be avoided by controlling the zero moment point or ZMP. The objective of this study is to propose and analyze a control strategy for simultaneously regulating the position of the ZMP and the joints of the robot. If the tracking requirements were posed in the time domain, the problem would be underactuated in the sense that the number of inputs would be less than the number of outputs. To get around this issue, the proposed controller is based on a pathfollowing control strategy previously developed for dealing with the underactuation present in planar robots without actuated ankles. In particular, the control law is defined in such a way that only the kinematic evolution of the robot’s state is regulated, but not its temporal evolution. The asymptotic temporal evolution of the robot is completely defined through a one degree of freedom subsystem of the closed-loop model. Since the ZMP is controlled, bipedal walking that includes a prescribed rotation of the foot about the toe can also be considered. Simple analytical conditions are deduced which guarantee the existence of a periodic motion and the convergence towards this motion

Assessing Aeolian Sand Potential in Ain Sefra Region - Southwestern of Algeria

Ain Sefra is a semi-arid area located in south-western Algeria carried out by sand barring, which has made any development in the area impossible. Thus, to understand this phenomenon, it is useful to estimate the displacement of the quantity of sand and the directions of the effective winds during 30 years (1985-2015) to quantify the phenomenon of silting and categorize the danger. Using the method of Fryberger, anemometric (wind) data from meteorological stations were analyzed to examine the potential for sand drift potential (DP) at Ain Sefra between 1985 and 2015. The objective is to identify the hazard level by estimating the sand displacement and effective wind directions over 30 years (1985-2015). The resulting (potential displacement) DP and directional wind variability are estimated and discussed. The average annual sand DP is expected to be 222VU (vector units). These figures have led to the classification of the Ain Sefra location as a wind environment with intermediate energy levels (medium energy wind environment) (Fryberger and Dean 1979). It is determined that the drift potential is 76 with a migration coefficient of 0.3 and that the area has a medium classification. It is also shown that the complex system of wind erosion and its interrelationship with other components are in play. The sand drift potential environment varies greatly from location to location, and 80% of the resulting annual PDR occurs during the fall season from March to June. In addition, effective winds often blow from the southwest to the northeast at an angle of 234°. In addition, the sand can be in different directions, leading it to drift. We should also mention that the directional variability is also quite hig

Climatic Sensitivity in the Algerian Steppes: Drought Indices and Remote Sensing

These last years, the Algerian steppe has known a strong degradation caused in particular by the scarcity of the annual rainfall. It spreads in certain cases to successive years generated by a persistent drought. A series of indices were applied to rainfall records recorded for 30 years (1985-2015) in the treated stations to identify the severity of the drought in the steppe regions. The present work proposes to study and compare the performance of some drought indices to identify a permanent monitoring system in the steppe. The indices studied are Pluviometric  Deficit Index (PDI), StandaPDIzed Precipitation Index (SPI), and the Ratio compared to the Normal (RN). We can deduce Climate variability is manifested by regressive spatio-temporal dynamics, thus, drought is recurrent phenomenon in the Algerian stepp