A time-dependent order parameter for ultrafast photoinduced phase transitions

Strongly correlated electron systems often exhibit very strong interactions between structural and electronic degrees of freedom that lead to complex and interesting phase diagrams. For technological applications of these materials it is important to learn how to drive transitions from one phase to another. A key question here is the ultimate speed of such phase transitions, and to understand how a phase transition evolves in the time domain. Here we apply time-resolved X-ray diffraction to directly measure the changes in long-range order during ultrafast melting of the charge and orbitally ordered phase in a perovskite manganite. We find that although the actual change in crystal symmetry associated with this transition occurs over different timescales characteristic of the many electronic and vibrational coordinates of the system, the dynamics of the phase transformation can be well described using a single time-dependent 'order parameter' that depends exclusively on the electronic excitation.

[What to do with a normal urinary strip in case of lower urinary tract symptoms?]

Patients very often consult for lower urinary tract symptoms, that do not necessarily equate to common cystitis. When urinary leucocytes and nitrites are absent, the urinary strip has a very good negative predictive value and makes the diagnosis of a lower urinary tract infection very unlikely. One then has to search for other diagnoses and to clarify the nature of the symptoms, irritating or obstructive ones, their duration and to correlate them to the patient's age and gender. In sexually active young patients, infectious diseases predominate, such as uretritis or vaginitis, while, with age, the prevalence of dysfunction of vesical emptying, benign prostatic hyperplasia or atrophic vaginitis increase.

Structural and magnetic dynamics of a laser induced phase transition in FeRh

We use time-resolved x-ray diffraction and magneto-optical Kerr effect to study the laser-induced antiferromagnetic to ferromagnetic phase transition in FeRh. The structural response is given by the nucleation of independent ferromagnetic domains (τ(1)~30 ps). This is significantly faster than the magnetic response (τ(2)~60 ps) given by the subsequent domain realignment. X-ray diffraction shows that the two phases coexist on short time scales and that the phase transition is limited by the speed of sound. A nucleation model describing both the structural and magnetic dynamics is presented.

Femtosecond dynamics of the collinear-to-spiral antiferromagnetic phase transition in CuO

We report on the ultrafast dynamics of magnetic order in a single crystal of CuO at a temperature of 207 K in response to strong optical excitation using femtosecond resonant x-ray diffraction. In the experiment, a femtosecond laser pulse induces a sudden, nonequilibrium increase in magnetic disorder. After a short delay ranging from 400 fs to 2 ps, we observe changes in the relative intensity of the magnetic ordering diffraction peaks that indicate a shift from a collinear commensurate phase to a spiral incommensurate phase. These results indicate that the ultimate speed for this antiferromagnetic reorientation transition in CuO is limited by the long-wavelength magnetic excitation connecting the two phases.

[Should we prescribe phosphodiesterase inhibitors for the treatment of symptomatic benign prostatic hyperplasia]

This October, the FDA has approved the use of phosphodiesterase inhibitors for the treatment of micurition symptoms due to benign prostatic hyperplasia, so as for erectile dysfunction. This decision is essentially based on the results of 2 studies that we discuss in this article. Although methodologically well designed, these works show that phosphodiesterase inhibitors decrease only weakly, but statistically sigificatively the micturition score of patients suffering from prostatism. Besides that, only one of these papers show a limited effect on a single objective micturitionnal parameter. According to the present knowledge, it appears judicious to prescribe tadalafil to treat benign prostatic hyperplasia symptoms of patients suffering simultaneously of a significant erectile dysfunction.

[Acute renal colic: which radiological exam in the GP daily practice?]

Nephrolithiasis is a common disease. Acute renal colic due to migration of stone is a frequent cause of admission in emergencies departements (ED). Diagnostic procedures in such centers are already well codified. This article discuss the diagnostic management and particularly the question of the radiological evaluation in patients presenting with renal colic to the general practitioner (GP). Because of the high risk of recurence and in order to identify patients with high stone burden, every patient presenting a first episode of renal colic should undergo radiological investigation. Considering sensitivity, irradiation rate, cost and diagnostic information, we recommend the (low-doses CT-SCAN as exam of choice for initial radiological evaluation of patient with renal colic.

[Minimally invasive ablation techniques for small kidney tumors: cryoablation and radiofrequency]

Over the last years, the development of minimally invasive surgery using percutaneous or laparoscopic ablative techniques for the treatment of small renal tumours has become more common. Cryotherapy and radiofrequency option have been now integrated in the armamentarium of the urologist. These approaches seem to be an attractive alternative to extirpative surgery in selected high-risk patients and offer on a short time basis equivalent cancer control to conventional surgery. This review presents recent data with regard to the use of cryotherapy and radiofrequency in the treatment of small renal tumours. These techniques will obviously have to stand the test of time.

[Usefullness of the Da Vinci robot in urologic surgery]

A telemanipulator for laparoscopic instruments is now available in the world of surgical robotics. This device has three distincts advantages over traditional laparoscopic surgery: it improves precision because of the many degrees of freedom of its instruments, and it offers 3-D vision so as better ergonomics for the surgeon. These characteristics are most useful for procedures that require delicate suturing in a focused operative field which may be difficult to reach. The Da Vinci robot has found its place in 2 domains of laparoscopic urologic surgery: radical prostatectomy and ureteral surgery. The cost of the robot, so as the price of its maintenance and instruments is high. This increases healthcare costs in comparison to open surgery, however not dramatically since patients stay less time in hospital and go back to work earlier.

A randomized prospective study of cefepime plus metronidazole with imipenem-cilastatin in the treatment of intra-abdominal infections

BACKGROUND

Presumptive antimicrobial therapy is an important aspect of the management of intra-abdominal infections. Together with surgery, antimicrobial combinations are still widely used to achieve the required spectrum of activity. The aim of this study was to evaluate the efficacy of parenteral cefepime + metronidazole vs imipenem-cilastatin for the treatment of intra-abdominal infections in adult patients.

METHODS

Patients with a clinically confirmed diagnosis of intra-abdominal infection were randomized to one of two treatment regimens: cefepime 2 g iv/12 h plus metronidazole 500 mg/8 h or imipenem-cilastatin 500 mg iv/6 h. The primary measure of clinical response was the decline of pre-treatment signs and symptoms of infection. The duration of follow-up was 30 days. Treatment failure was defined as either a lack of improvement or a worsening of pre-treatment signs and symptoms of infection. Surgical management of the infection was determined by the surgeon-in-charge.

RESULTS

Of the 122 intended-to-treat patients included in the study, 60 patients (33 men) were randomized to cefepime + metronidazole and 61 (27 men) to imipenem-cilastatin. Cefepime + metronidazole treatment was successful in 52 (87%) patients and imipenem-cilastatin in 44 (72%) patients (p = 0.004). Microbiological eradication was established in similar proportions in both groups (cefepime + metronidazole, 43; imipenem-cilastatin, 38).

CONCLUSION

Further studies are warranted to confirm the better results with the cefepime + metronidazole regimen for the treatment of intra-abdominal infections.

Novel injectable urethral bulking agents for the treatment of urinary incontinence

Stress urinary incontinence is a highly prevalent disorder resulting from weak urethral closure mechanisms. Endoscopic injection of a urethral bulking agent (UBA) under the urethral mucosa increases coaptation, which improves continence. Collagen is an efficient agent, although its effects are limited in time. Other materials still suffer either from a short-lasting effect or migration in distant organs. We evaluated here novel UBAs using an ex vivo model, with respect to criteria of ease of injection, ability to form a high and stable tissue bulking, implant elasticity and tissue reaction. One approach involves solutions of polymers in water-miscible organic solvents that precipitates in situ. In this manner, high and stable bulks were routinely obtained using various commercial polymers. Selected solvents reduced the tissue reaction to the implant. Microsphere suspensions in hydrogels also proved to be efficient UBA, although less stable bulks were obtained. Thermosetting chitosan hydrogels showed promising results with respect to bulk stability and isoelasticity with surrounding tissues. Different strategies have thus been compared and optimised ex vivo. Further experiments are required to compare the ability of these materials to induce a sustained in vivo bulking effect.