Superfluid fraction in an interacting spatially modulated Bose-Einstein condensate

At zero temperature, a Galilean-invariant Bose fluid is expected to be fully superfluid. Here we investigate theoretically and experimentally the quenching of the superfluid density of a dilute Bose-Einstein condensate due to the breaking of translational (and thus Galilean) invariance by an external 1D periodic potential. Both Leggett's bound fixed by the knowledge of the total density and the anisotropy of the sound velocity provide a consistent determination of the superfluid fraction. The use of a large-period lattice emphasizes the important role of two-body interactions on superfluidity

Fast electron transport and heating in solid-density matter

Two experiments have been performed to investigate heating by high-intensity laser-generated electrons, in the context of studies of the fast ignitor approach to inertial confinement fusion (ICF). A new spectrometer and layered targets have been used to detect Kα emission from aluminum heated by a fast electron beam. Results show that a temperature of about 40 eV is reached in solid density aluminum up to a depth of about 100 μm

Superfluid fraction in an interacting spatially modulated Bose-Einstein condensate

At zero temperature, a Galilean-invariant Bose fluid is expected to be fully superfluid. Here we investigate theoretically and experimentally the quenching of the superfluid density of a dilute Bose-Einstein condensate due to the breaking of translational (and thus Galilean) invariance by an external 1D periodic potential. Both Leggett's bound fixed by the knowledge of the total density and the anisotropy of the sound velocity provide a consistent determination of the superfluid fraction. The use of a large-period lattice emphasizes the important role of two-body interactions on superfluidity

Proposals from a French expert panel for respiratory care in ALS patients

International audienceBackground: Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by progressive diaphragm weakness and deteriorating lung function. Bulbar involvement and cough weakness contribute to respiratory morbidity and mortality. ALS-related respiratory failure significantly affects quality of life and is the leading cause of death. Non-invasive ventilation (NIV), which is the main recognized treatment for alleviating the symptoms of respiratory failure, prolongs survival and improves quality of life. However, the optimal timing for the initiation of NIV is still a matter of debate. NIV is a complex intervention. Multiple factors influence the efficacy of NIV and patient adherence. The aim of this work was to develop practical evidence-based advices to standardize the respiratory care of ALS patients in French tertiary care centres. Methods: For each proposal, a French expert panel systematically searched an indexed bibliography and prepared a written literature review that was then shared and discussed. A combined draft was prepared by the chairman for further discussion. All of the proposals were unanimously approved by the expert panel. Results: The French expert panel updated the criteria for initiating NIV in ALS patients. The most recent criteria were established in 2005. Practical advice for NIV initiation were included and the value of each tool available for NIV monitoring was reviewed. A strategy to optimize NIV parameters was suggested. Revisions were also suggested for the use of mechanically assisted cough devices in ALS patients. Conclusion: Our French expert panel proposes an evidence-based review to update the respiratory care recommendations for ALS patients in daily practice

Study of the propagation of ultra-intense laser-produced fast electrons in gas jets

We present the results of some recent experiments performed at the LULI laboratory using the 100 TW laser facility concerning the study of the propagation of fast electrons in gas targets. Novel diagnostics have been implemented including chirped shadowgraphy and proton radiography. Proton radiography images did show the presence of very strong fields in the gas probably produced by charge separation. In turn, these imply a slowing down of the fast electron cloud as it penetrates in the gas, and a strong inhibition of propagation. Indeed chirped shadowgraphy images show a strong reduction of the electron cloud velocity from the initial value close to a fraction of c

Benefits of non-invasive ventilation in acute hypercapnic respiratory failure

Non-invasive ventilation (NIV) with bilevel positive airway pressure is a non-invasive technique, which refers to the provision of ventilatory support through the patient's upper airway using a mask or similar device. This technique is successful in correcting hypoventilation. It has become widely accepted as the standard treatment for patients with hypercapnic respiratory failure (HRF). Since the 1980s, NIV has been used in intensive care units and, after initial anecdotal reports and larger series, a number of randomized trials have been conducted. Data from these trials have shown that NIV is a valuable treatment for HRF. This review aims to explore the principal areas in which NIV can be useful, focusing particularly on patients with acute HRF (AHRF). We will update the evidence base with the goal of supporting clinical practice. We provide a practical description of the main indications for NIV in AHRF and identify the group of patients with hypercapnic failure who will benefit most from the application of NIV

Study of the propagation of ultra-intense laser-produced fast electrons in gas jets

We present the results of some recent experiments performed at the LULI laboratory using the 100 TW laser facility concerning the study of the propagation of fast electrons in gas targets. Novel diagnostics have been implemented including chirped shadowgraphy and proton radiography. Proton radiography images did show the presence of very strong fields in the gas probably produced by charge separation. In turn, these imply a slowing down of the fast electron cloud as it penetrates in the gas, and a strong inhibition of propagation. Indeed chirped shadowgraphy images show a strong reduction of the electron cloud velocity from the initial value close to a fraction of c