4e-condensation in a fully frustrated Josephson junction diamond chain

Fully frustrated one-dimensional diamond Josephson chains have been shown [B. Dou\c{c}ot and J. Vidal, Phys. Rev. Lett. {\bf 88}, 227005 (2002)] to posses a remarkable property: The superfluid phase occurs through the condensation of pairs of Cooper pairs. By means of Monte Carlo simulations we analyze quantitatively the Insulator to $4e$-Superfluid transition. We determine the location of the critical point and discuss the behaviour of the phase-phase correlators. For comparison we also present the case of a diamond chain at zero and 1/3 frustration where the standard $2e$-condensation is observed.Comment: 5 pages, 7 figure

High domain wall velocities induced by current in ultrathin Pt/Co/AlOx wires with perpendicular magnetic anisotropy

Current-induced domain wall (DW) displacements in an array of ultrathin Pt/Co/AlOx wires with perpendicular magnetic anisotropy have been directly observed by wide field Kerr microscopy. DWs in all wires in the array were driven simultaneously and their displacement on the micrometer-scale was controlled by the current pulse amplitude and duration. At the lower current densities where DW displacements were observed (j less than or equal to 1.5 x 10^12 A/m^2), the DW motion obeys a creep law. At higher current density (j = 1.8 x 10^12 A/m^2), zero-field average DW velocities up to 130 +/- 10 m/s were recorded.Comment: Minor changes to Fig. 1(b) and text, correcting for the fact that domain walls were subsequently found to move counter to the electron flow. References update

Magnetic screening in proximity effect Josephson-junction arrays

The modulation with magnetic field of the sheet inductance measured on proximity effect Josephson-junction arrays (JJAs) is progressively vanishing on lowering the temperature, leading to a low temperature field-independent response. This behaviour is consistent with the decrease of the two-dimensional penetration length below the lattice parameter. Low temperature data are quantitatively compared with theoretical predictions based on the XY model in absence of thermal fluctuations. The results show that the description of a JJA within the XY model is incomplete and the system is put well beyond the weak screening limit which is usually assumed in order to invoke the well known frustrated XY model describing classical Josephson-junction arrays.Comment: 6 pages, 5 figure

Insight. Transgenic solutions to increase yield and stability in wheat: shining hope or flash in the pan?

Second-generation transgenic crops have the potential to transform agriculture, but progress has been limited, and particularly so in wheat where no transgenic cultivar has yet been approved. Taking on the challenge, González et al. (2019) report that transgenic wheat lines carrying a mutated version of the sunflower transcription factor (HaHB4), belonging to the homeodomain-leucine zipper family (HD-Zip I), had increased yield and water use efficiency across a range of environments, with particular benefits under stress. It is an important step forward in an area where progress is urgently needed, though it is too early to claim that transgenic wheat will form the backbone of a second Green Revolution. To meet the growing demand for food, together with the challenges imposed by climate change, substantial improvements in yields of major crops are needed. This includes wheat, where globally the multi-year tendency for growth in yield is decreasing (Passioura, 2012) or even stagnating (Driever et al., 2017). Current and expected future relative rates of progress in yield potential and drought adaptation in wheat are a matter of real concern, and insufficient to meet the projected demand for cereals by 2050 (Hall and Richards, 2013). There are three major challenges: increasing yield potential, protecting yield potential from different types of stress, and increasing resource use efficiency to ensure sustainability (Hawkesford et al., 2013)

Projective dynamics and classical gravitation

Given a real vector space V of finite dimension, together with a particular homogeneous field of bivectors that we call a "field of projective forces", we define a law of dynamics such that the position of the particle is a "ray" i.e. a half-line drawn from the origin of V. The impulsion is a bivector whose support is a 2-plane containing the ray. Throwing the particle with a given initial impulsion defines a projective trajectory. It is a curve in the space of rays S(V), together with an impulsion attached to each ray. In the simplest example where the force is identically zero, the curve is a straight line and the impulsion a constant bivector. A striking feature of projective dynamics appears: the trajectories are not parameterized. Among the projective force fields corresponding to a central force, the one defining the Kepler problem is simpler than those corresponding to other homogeneities. Here the thrown ray describes a quadratic cone whose section by a hyperplane corresponds to a Keplerian conic. An original point of view on the hidden symmetries of the Kepler problem emerges, and clarifies some remarks due to Halphen and Appell. We also get the unexpected conclusion that there exists a notion of divergence-free field of projective forces if and only if dim V=4. No metric is involved in the axioms of projective dynamics.Comment: 20 pages, 4 figure

The Nuclear Receptor LXR Limits Bacterial Infection of Host Macrophages through a Mechanism that Impacts Cellular NAD Metabolism

Macrophages exert potent effector functions against invading microorganisms but constitute, paradoxically, a preferential niche for many bacterial strains to replicate. Using a model of infection by Salmonella Typhimurium, we have identified a molecular mechanism regulated by the nuclear receptor LXR that limits infection of host macrophages through transcriptional activation of the multifunctional enzyme CD38. LXR agonists reduced the intracellular levels of NAD+ in a CD38-dependent manner, counteracting pathogen-induced changes in macrophage morphology and the distribution of the F-actin cytoskeleton and reducing the capability of non-opsonized Salmonella to infect macrophages. Remarkably, pharmacological treatment with an LXR agonist ameliorated clinical signs associated with Salmonella infection in vivo, and these effects were dependent on CD38 expression in bone-marrow-derived cells. Altogether, this work reveals an unappreciated role for CD38 in bacterial-host cell interaction that can be pharmacologically exploited by activation of the LXR pathway

Learning to Teach About Ideas and Evidence in Science : The Student Teacher as Change Agent

A collaborative curriculum development project was set up to address the lack of good examples of teaching about ideas and evidence and the nature of science encountered by student teachers training to teach in the age range 11-16 in schools in England. Student and teacher-mentor pairs devised, taught and evaluated novel lessons and approaches. The project design required increasing levels of critique through cycles of teaching, evaluation and revision of lessons. Data were gathered from interviews and students' reports to assess the impact of the project on student teachers and to what extent any influences survived when they gained their first teaching posts. A significant outcome was the perception of teaching shifting from the delivery of standard lessons in prescribed ways to endeavours demanding creativity and decision-making. Although school-based factors limited newly qualified teachers' chances to use new lessons and approaches and therefore act as change-agents in schools, the ability to critique curriculum materials and the recognition of the need to create space for professional dialogue were durable gains

Temperature dependence of planktonic metabolism in the subtropical North Atlantic Ocean

The temperature dependence of planktonic metabolism in the subtropical North Atlantic Ocean was assessed on the basis of measurements of gross primary production (GPP), community respiration (CR) and net community production (NCP), as well as experimental assessments of the response of CR to temperature manipulations. Metabolic rates were measured at 68 stations along three consecutive longitudinal transects completed during the Malaspina 2010 Expedition, in three different seasons. Temperature gradients were observed in depth and at basin and seasonal scale. The results showed seasonal variability in the metabolic rates, the highest rates being observed during the spring transect. The overall mean integrated GPP / CR ratio was 1.39 ± 0.27 decreasing from winter to summer, and the NCP for the subtropical North Atlantic Ocean during the cruises exhibits net autotrophy (NCP > 0) in about two-thirds (66%) of the total sampled communities. Also, we reported the activation energies describing the temperature dependence of planktonic community metabolism, which was generally higher for CR than for GPP in the subtropical North Atlantic Ocean, as the metabolic theory of ecology predicts. Furthermore, we made a comparison of activation energies describing the responses to in situ temperature in the field (EaCR = 1.64 ± 0.36 eV) and those derived experimentally by temperature manipulations (EaCR = 1.45 ± 0.6 eV), which showed great consistency

GOLIAH (Gaming Open Library for Intervention in Autism at Home): a 6-month single blind matched controlled exploratory study

BackgroundTo meet the required hours of intensive intervention for treating children with autism spectrum disorder (ASD), we developed an automated serious gaming platform (11 games) to deliver intervention at home (GOLIAH) by mapping the imitation and joint attention (JA) subset of age-adapted stimuli from the Early Start Denver Model (ESDM) intervention. Here, we report the results of a 6-month matched controlled exploratory study.MethodsFrom two specialized clinics, we included 14 children (age range 5–8 years) with ASD and 10 controls matched for gender, age, sites, and treatment as usual (TAU). Participants from the experimental group received in addition to TAU four 30-min sessions with GOLIAH per week at home and one at hospital for 6 months. Statistics were performed using Linear Mixed Models.ResultsChildren and parents participated in 40% of the planned sessions. They were able to use the 11 games, and participants trained with GOLIAH improved time to perform the task in most JA games and imitation scores in most imitation games. GOLIAH intervention did not affect Parental Stress Index scores. At end-point, we found in both groups a significant improvement for Autism Diagnostic Observation Schedule scores, Vineland socialization score, Parental Stress Index total score, and Child Behavior Checklist internalizing, externalizing and total problems. However, we found no significant change for by time × group interaction.ConclusionsDespite the lack of superiority of TAU + GOLIAH versus TAU, the results are interesting both in terms of changes by using the gaming platform and lack of parental stress increase. A large randomized controlled trial with younger participants (who are the core target of ESDM model) is now discussed. This should be facilitated by computing GOLIAH for a web platform.Trial registration Clinicaltrials.gov NCT0256041

Case report: an unexpected link between partial deletion of the SHANK3 gene and Heller’s dementia infantilis, a rare subtype of autism spectrum disorder

International audienceAbstractBackgroundDeletions and mutations involving the SHANK3 gene lead to a nonspecific clinical presentation with moderate to profound intellectual disability, severely delayed or absent speech, and autism spectrum disorders (ASD).Better knowledge of the clinical spectrum of SHANK3 haploinsufficiency is useful to facilitate clinical care monitoring and to guide molecular diagnosis, essential for genetic counselling.Case presentationHere, we report a detailed clinical description of a 10-year-old girl carrying a pathogenic interstitial 22q13.3 deletion encompassing only the first 17 exons of SHANK3.The clinical features displayed by the girl strongly suggested the diagnosis of dementia infantilis, described by Heller in 1908, also known as childhood disintegrative disorder.ConclusionOur present case confirms several observations according to which regression may be part of the clinical phenotype of SHANK3 haploinsufficiency. Therefore, we think it is crucial to look for mutations in the gene SHANK3 in patients diagnosed for childhood disintegrative disorder or any developmental disorder with a regressive pattern involving social and communicative skills as well as cognitive and instinctual functions, with onset around 3 years