Unified force law for granular impact cratering

Experiments on the low-speed impact of solid objects into granular media have been used both to mimic geophysical events and to probe the unusual nature of the granular state of matter. Observations have been interpreted in terms of conflicting stopping forces: product of powers of projectile depth and speed; linear in speed; constant, proportional to the initial impact speed; and proportional to depth. This is reminiscent of high-speed ballistics impact in the 19th and 20th centuries, when a plethora of empirical rules were proposed. To make progress, we developed a means to measure projectile dynamics with 100 nm and 20 us precision. For a 1-inch diameter steel sphere dropped from a wide range of heights into non-cohesive glass beads, we reproduce prior observations either as reasonable approximations or as limiting behaviours. Furthermore, we demonstrate that the interaction between projectile and medium can be decomposed into the sum of velocity-dependent inertial drag plus depth-dependent friction. Thus we achieve a unified description of low-speed impact phenomena and show that the complex response of granular materials to impact, while fundamentally different from that of liquids and solids, can be simply understood

Power Doppler ultrasonography is useful for assessing disease activity and predicting joint destruction in rheumatoid arthritis patients receiving tocilizumab—preliminary data

To evaluate the responsiveness of power Doppler ultrasonography (PDUS) in comparison with conventional measures of disease activity and structural damage in rheumatoid arthritis (RA) patients receiving tocilizumab (TCZ). Seven RA patients with active arthritis were enrolled in the study and prospectively monitored for 12 months. They were treated with TCZ (8 mg/kg) every 4 weeks as monotherapy or in combination with disease-modifying antirheumatic drugs (DMARDs). Clinical, laboratory, and ultrasound examinations were conducted at baseline, 1, 3, 6, 9, and 12 months. Power Doppler (PD) signals were graded from 0 to 3 in 24 joints, and total PD score was calculated as the sum of scores of individual joints. One-year radiographic progression of the hands was estimated by using Genant-modified Sharp scoring. The averages of the clinical parameters rapidly improved, and all patients achieved good response within 6 months based on standard 28-joint Disease Activity Score (DAS28). Although the average total PD score declined in parallel with clinical improvement, radiography of the hands showed progression of destruction in the joints where PD signals remained, even among clinical responders. ΔSharp score correlated with the time-integrated value (TIV) of total PD scores (Δtotal Sharp score: r = 0.77, P = 0.04; Δerosion: r = 0.78, P = 0.04; Δjoint-space narrowing (JSN): r = 0.75, P = 0.05), but not with TIVs of clinical parameters including DAS28. PDUS can independently evaluate disease activity in RA patients receiving TCZ and is superior to DAS28, especially in predicting joint destruction

Transgenic tobacco plants constitutively expressing Arabidopsis NPR1 show enhanced resistance to root-knot nematode, Meloidogyne incognita

In Arabidopsis, non-expressor of pathogenesis related genes-1, NPR1 has been shown to be a positive regulator of the salicylic acid controlled systemic acquired resistance pathway and modulates the cross talk between SA and JA signaling. Transgenic plants expressing AtNPR1 constitutively exhibited resistance against pathogens as well as herbivory. In the present study, tobacco transgenic plants expressing AtNPR1 were studied further for their response to infection by the sedentary endoparasitic root knot nematode, Meloidogyne incognita. Transgenic plants showed enhanced resistance against the root-knot nematode infection. Prominent differences in the shoot and root weights of wild type and transgenic plants were observed post-inoculation with M. incognita. This was associated with a decrease in the number of root galls and egg masses in transgenic plants compared to WT. The transgenic plants also showed constitutive and induced expression of some PR protein genes, when challenged with M. incognita

Dysgerminoma in three patients with Swyer syndrome

<p>Abstract</p> <p>Background</p> <p>Dysgerminoma is the most common malignant germ cell tumor of the ovary. This malignancy can be associated with pure gonadal dysgenesis or Swyer syndrome, mixed gonadal dysgenesis and partial gonadal dysgenesis.</p> <p>Case presentation</p> <p>Dysgerminoma developed in 3 phenotypic female patients with 46 XY pure gonadal dysgenesis. All patients presented first with abdominopelvic mass. Laparatomy was done. 46 XY karyotype was made by lymphocyte culture. Then these patients underwent gonadectomy that histopathology results were streak ovaries without evidence for malignancy. Two patients received postoperative adjuvant therapy.</p> <p>Conclusion</p> <p>In Patients with Swyer syndrome the risk of dysgerminoma is high and gonadectomy is recommended. Also 5% of dysgerminomas are discovered in phenotypic female and 46 XY karyotype, thus in adolescent with dysgerminoimas and amenorrhea, karyotype should be done.</p

Oral-Derived Bacterial Flora Defends Its Domain by Recognizing and Killing Intruders—A Molecular Analysis Using Escherichia coli as a Model Intestinal Bacterium

Within the same human gastrointestinal tract, substantial differences in the bacterial species that inhabit oral cavity and intestinal tract have been noted. Previous research primarily attributed the differences to the influences of host environments and nutritional availabilities (“host habitat” effect). Our recent study indicated that, other than the host habitat effect, an existing microbial community could impose a selective pressure on incoming foreign bacterial species independent of host-mediated selection (“community selection” effect). In this study, we employed in vitro microbial floras representing microorganisms that inhabit the oral cavities and intestinal tract of mice in combination with Escherichia coli as a model intestinal bacterium and demonstrated that E. coli displays a striking community preference. It thrived when introduced into the intestinal microbial community and survived poorly in the microbial flora of foreign origin (oral community). A more detailed examination of this phenomenon showed that the oral community produced oxygen-free radicals in the presence of wild-type E. coli while mutants deficient in lipopolysaccharides (LPS) did not trigger significant production of these cell-damaging agents. Furthermore, mutants of E. coli defective in the oxidative stress response experienced a more drastic reduction in viability when cocultivated with the oral flora, while the exogenous addition of the antioxidant vitamin C was able to rescue it. We concluded that the oral-derived microbial community senses the E. coli LPS and kills the bacterium with oxygen-free radicals. This study reveals a new mechanism of community invasion resistance employed by established microflora to defend their domains

Cooperative dynamics in the penetration of a group of intruders in a granular medium

An object moving in a fluid experiences a drag force that depends on its velocity, shape and the properties of the medium. From this simplest case to the motion of a flock of birds or a school of fish, the drag forces and the hydrodynamic interactions determine the full dynamics of the system. Similar drag forces appear when a single projectile impacts and moves through a granular medium, and this case is well studied in the literature. On the other hand, the case in which a group of intruders impact a granular material has never been considered. Here, we study the simultaneous penetration of several intruders in a very low-density granular medium. We find that the intruders move through it in a collective way, following a cooperative dynamics, whose complexity resembles flocking phenomena in living systems or the movement of reptiles in sand, wherein changes in drag are exploited to efficiently move or propel

Search for CP violation in the decay B0->D*+-D-+

We report a search for CP-violating asymmetry in B0 -> D*+- D-+ decays. The analysis employs two methods of B0 reconstruction: full and partial. In the full reconstruction method all daughter particles of the B0 are required to be detected; the partial reconstruction technique requires a fully reconstructed D- and only a slow pion from the D*+ -> D0 pi_slow+ decay. From a fit to the distribution of the time interval corresponding to the distance between two B meson decay points we calculate the CP-violating parameters and find the significance of nonzero CP asymmetry to be 2.7 standard deviations.Comment: 4 pages, 3 figure

Prime movers : mechanochemistry of mitotic kinesins

Mitotic spindles are self-organizing protein machines that harness teams of multiple force generators to drive chromosome segregation. Kinesins are key members of these force-generating teams. Different kinesins walk directionally along dynamic microtubules, anchor, crosslink, align and sort microtubules into polarized bundles, and influence microtubule dynamics by interacting with microtubule tips. The mechanochemical mechanisms of these kinesins are specialized to enable each type to make a specific contribution to spindle self-organization and chromosome segregation