Together with the advanced growth technologies of zinc selenide epitaxial films by MOVPE or MBE, severals workers have reported the observation of p-type conductivity in this material. However, there are some inconsistencies in most of the papers reporting such results. We report here the MOVPE crystal growth of nominaly undoped ZnSe/GaAs S.I. layers using alkyls as precursors, and their optical and electrical characterizations. We show the possibility to observe p-type conductivity in ZnSe due to a hole accumulation at the interface in the GaAs side. This is consistent with a simple model taking Into account the conduction and valence bands discontinuities at the ZnSe/GaAs interface.

Introduction : Information on prostate diseases, including prostate cancer; has been promoted by the Association Francaise d'Urologie (AFU) for several years, but is developing slowly in France. In 2005, a first communication was targeted to the male public and identified the reasons for the finalistic attitude of men, and paradoxically, why the prostate incarnates the vulnerability of their sexual capital. As part of a second phase, this article presents the results of a complementary study conducted among general practitioners to identify their expectations and the most appropriate levers to promote screening. Material and Method: The Ipsos survey company developed a Krisis (TM) qualitative protocol in October 2005 (after the first French prostate day on 15 September 2005). Three groups of general practitioners were defined: doctors who are very active in terms of screening, doctors who are uncomfortable with this problem and doctors who systematically their patients to urologists. Results: The management at prostate diseases often highlights the ageing process for the patient. The ability to discuss these problems during the consultation depended on the doctor's degree of comfort with this subject, which is related to his/her training and relationships with urologists. To initiate the question of screening, general practitioners involved in this process asked simple questions about everyday practices without being afraid of making jokes or basing their approach on mediatization of the disease. Digital rectal examination is one of the important clinical elements but is not always easy to perform. PSA was found to be an examination that is not always appropriate, characterized by a lack of information on the conditions for ordering this test, its usefulness and its relevance for screening. Ultrasound could be a way of alerting the patient without dramatizing the situation, letting the urologist perform digital rectal examination. Female general practitioners preferred PSA and ultrasound. The doctors surveyed relied on mediatization of prostate diseases, a high level of interactivity with urologists and documents and brochures to be placed in waiting rooms to relay screening messages. Conclusion : General practitioners need their authorities, specialists and public health institutions to develop and mediatize andrology, in the same way as gynaecology Urologists play a major supportive role by means of conferences, postgraduate training or AFU invitations.

Objective: Congenital giant hydronephrosis due to ureteropelvic junction obstruction is exceptional and treatment often requires nephrectomy of a poorly functioning kidney. However a more conservative approach by nephroplication is also possible. The objective of this study was to evaluate the long-term functional outcome of these kidneys treated by nephroplication during the neonatal period.Material and Methods: From 1996 to 1998, 5 neonates with congenital giant hydronephrosis were managed in our department (3 antenatal diagnoses). The mean anteroposterior pelvic dilatation was 145 mm (range: 110-180 mm). All infants were treated by pyeloplasty with nephroplication, regardless of the preoperative ultrasound and scintigraphic appearance of the renal parenchyma.Results: The mean follow-up was 9 years (range: 8-10 years). A marked initial reduction of global kidney volume was constantly observed (more than 50% of the initial volume). The mean relative renal function was 32.4% (range: 10-42%) without any residual obstruction. Renal growth was satisfactory in 4 cases (40 mm at I year 72 mm at 6 years) with an atrophic kidney in 1 case. No child developed hypertension or elevated serum creatinine.Conclusion: Congenital giant hydronephrosis does not systematically justify primary nephrectomy even in the presence of a healthy contralateral kidney. Despite the pejorative initial ultrasound and scintigraphic appearance, which is always difficult to interpret, early nephroplication improves drainage of pyelocaliceal cavities, decreases the residual dilatation and allows significant nephron sparing in most of these children.

Cryptorchidism is a very common anomaly of testicular migration, different from ectopy, anorchidy or retractile testis. Physiopathology of cryptorchidism is now well known. Hypogonadotrophic hypogonadism during pregnancy is mostly admitted. Recent epidemiologic studies show a significant increase due to toxic environmental factors, in particular pesticide. Cryptorchidism is most often isolated but polymalformatives entities must be eliminated, requiring sometimes hormonal or genetic investigations. Diagnosis is firstly clinical but coelioscopy adds accuracy and fiability. Infertility and cancer are the two majors risks of cryptorchidism, but their physiopathological mechanisms are still debated. It is not yet clear, in particular as far as the risk of infertility is concerned, if the testicular damage is primitive or (and) deteriorates with age. Medical and surgical treatments are now rather well codified. If, so far, there is no consensus about the age of management of cryptorchidism, many data of the literature lead pediatric urologists to manage these boys as soon as they are two or three.

La cryptorchidie est une anomalie de la migration testiculaire qu'il ne faut pas confondre avec le testicule ectopique, le testicule oscillant, le testicule évanescent ou l'anorchidie. La physiopathologie de la cryptorchidie est mieux connue et relève souvent d'un hypogonadisme hypogonadotrophique durant la grossesse, probablement majoré comme le montrent les études épidémiologiques récentes par des facteurs environnementaux toxiques au premier rang desquels figurent les pesticides. La cryptorchidie est le plus souvent banale mais peut être également associée à d'autres anomalies polymalformatives, imposant un bilan hormonal plus ou moins poussé, parfois un caryotype. Le diagnostic est avant tout clinique mais sa précision a été transformée par la cœlioscopie. Infertilité et cancérisation sont les deux risques majeurs de la cryptorchidie. Les mécanismes restent pourtant très discutés. On ne sait toujours pas, surtout pour le risque d'infertilité, si les lésions testiculaires sont primitives et si le temps les aggrave. Les traitements médicaux ou chirurgicaux sont maintenant bien définis. S'il n'y a toujours pas de consensus sur l'âge de la prise en charge de la cryptorchidie, bien des arguments incitent cependant l'urologue pédiatre à traiter précocement, autour de l'âge de deux à trois ans les enfants porteurs d'une cryptorchidie. Cryptorchidism is a very common anomaly of testicular migration, different from ectopy, anorchidy or retractile testis. Physiopathology of cryptorchidism is now well known. Hypogonadotrophic hypogonadism during pregnancy is mostly admitted. Recent epidemiologic studies show a significant increase due to toxic environmental factors, in particular pesticide. Cryptorchidism is most often isolated but polymalformatives entities must be eliminated, requiring sometimes hormonal or genetic investigations. Diagnosis is firstly clinical but coelioscopy adds accuracy and fiability. Infertility and cancer are the two majors risks of cryptorchidism, but their physiopathological mechanisms are still debated. It is not yet clear, in particular as far as the risk of infertility is concerned, if the testicular damage is primitive or (and) deteriorates with age. Medical and surgical treatments are now rather well codified. If, so far, there is no consensus about the age of management of cryptorchidism, many data of the literature lead pediatric urologists to manage these boys as soon as they are two or three.

SiC/Si(111) heterostructures formed by using an alternative method for stress relaxation were investigated by SIMS and AES. The applied stress reduction method is based on a theoretical approach, which predicts an improvement of the SiC layer quality if Group IV elements are incorporated into the interface between SiC and Si. Germanium was chosen to test this approach. The incorporation of Ge into the heterointerface was carried out by depositing different amounts of Ge prior to the SiC growth process and varying the Ge deposition temperature. SIMS investigations revealed that Ge remains near the SiC/Si interface independently of the pre‐deposited amount of Ge. In the case of two monolayers (ML) Ge coverage (with respect to the silicon surface) a surface segregation was observed. This indicates a limited transport of Ge to the SiC surface through the growing SiC layer due to grain boundary diffusion. At Ge coverages between 0.5 ML and 2 ML a sharper interface between the SiC and Si was observed. In this case the tail of the carbon distribution remains within the region occupied by the Ge distribution. The incorporation of Ge at the interface suppresses the out‐diffusion of Si from the substrate to the surface of the growing SiC layer and, therefore, impedes the formation of voids at the SiC/Si interface. Copyright © 2004 John Wiley & Sons, Ltd.

Background Pelvi-ureteric junction (PUJ) obstruction is caused by the presence of an aperistaltic dysplastic segment at the PUJ. Besides this intrinsic aetiology, extrinsic abnormalities, mainly crossing vessels, may be an associated factor. Objective To determine the reliability of colour Doppler US in the detection of crossing vessels in children with surgically proven PUJ obstruction. Materials and methods Forty-eight patients (50 kidneys) with PUJ obstruction, surgically treated from 1998 to 2001, were prospectively studied by colour Doppler US prior to open pyeloplasty. There were 33 boys and 15 girls (age 2 months—12 years; median 3.5 years). There were 24 right kidneys and 26 left kidneys. The indication for surgery was according to the usual criteria. The crossing vessel was considered as present when depicted on colour Doppler US at the PUJ. Results Colour Doppler assessment of the crossing vessels was correct in all but two patients. At surgery, a crossing vessel was found in 14 kidneys (i.e. 28%). Colour Doppler US results were correlated with intra-operative findings in 50 renal units. Surgically proven vessels in 14 kidneys were identified by colour Doppler US in 13, and not shown in 1. In PUJ obstruction without a crossing vessel ( n =36), US findings were concordant in 26, discordant in 8 and inconclusive in 2 (with kidney malrotation) cases. Colour Doppler US had a sensitivity (Se), specificity (Sp), positive predictive value (PPV), negative predictive value (NPV), and accuracy of 92.8%, 76.5%, 62%, 96.3% and 78%, respectively. The reliability of colour Doppler US was greatly improved with the increasing experience of the sonographer, as shown by the results of the last 2 years (26 kidneys):Se=100%, Sp=87.5%, PPV=81.8%, NPV=100%, accuracy=88.5%. Conclusions Colour Doppler US is reliable in the detection of crossing vessels at the PUJ.

The T-dependence of the resistivity rho of a start-of-the-art polycrystalline sample of CeFe4Sb12 was measured between 5 and 300 K. The cerium contribution to the resistivity, rho(Ce) was obtained by substracting the resistivity of LaFe4Sb12. As a function of T, rho(Ce) exhibits a maximum near 150 K. This maximum is attributed to a combination of a Crystal Electric Field (CEF) and the Kondo effect. This interpretation is consistent with Hall data in the same temperature range. Our heat capacity data confirm that the electronic specific heat coefficient gamma for LaFe4Sb12 is larger than that for CeFe4Sb12. The Debye temperatures of both materials are near 250 K.

OBJECTIVE:To define the diagnostic and therapeutic value of foetal urine sampling (FUS).MATERIAL AND METHOD:Between 1996 and 2001, FUS was performed in 16 patients for three indications: assessment of renal function (Group 1, n = 12), diagnosis of a cystic mass (Group 2, n = 2), prevention of dystocia (Group 3, n = 2). The anomaly was detected by ultrasound. Urine was aspirated from the two renal pelves and/or bladder, or the cystic mass in the other cases. b2-microglobulin and urinary sodium were assayed and karyotyping was performed at the same time.RESULTS:20 FUS were performed In 4 cases, two samples were taken at an interval of 2 weeks. No complications were observed. Group 1: 9 pregnancies were terminated for potential renal failure (6 posterior urethral valves (PUV), 1 Prune Belly syndrome, 2 cases of recessive polycystic kidney disease (PKD). Three pregnancies were continued for 2 foetuses with normal renal function (1 PUV, 1 ureterocele) and one foetus died with severe renal failure (bilateral hydronephrosis). Group 2: one termination of pregnancy was performed in a case of hepatic cyst with portobiliary dysplasia and a giant bladder diverticulum was operated. Group 3: in both cases, evacuating aspiration allowed normal delivery of one live infant (left polycystic dysplasia), and one neonatal death from megabladder-megacolon syndrome.DISCUSSION:The value of FUS is controversial. We usually performed this examination for assessment of renal function. The results of FUS are useful for management decisions when they are in favour of potential impaired renal function. They usually confirmed the ultrasound results that already indicated a poor prognosis and they did not change the decision already based on ultrasound findings in any of our cases. For the diagnosis of cystic masses, after drainage of the mass, FUS facilitated investigation of the urinary tract and adjacent organs. When FUS was performed during labour, it reduced the size of the mass and the abdomen, allowing vaginal delivery with a better ventilatory adaptation of the infant.

In heteroepitaxial growth experiments, the choice of the substrate is a key step for the realization of high-quality overlayers. This strategy imposes constraints in terms of interface optimization. This optimization can be achieved (i) by selecting a substrate which matches the overlayer properties and (ii) when this matching can not be realized at a high level, by using an optimizing growth process (e.g., buffer layer BL-assisted heteroepitaxy) In this work, we discuss these problems within the framework of a theoretical approach [I] based on the elasticity theory.

Group III-nitride is one of the best candidate for UV lasers-diodes, LEDs and UV sensors. Gallium nitride-based opto-electronic devices may possess high emission efficiency because of its electronic properties. In order to obtain high quality GaN crystalline films, the problem of finding an optimized substrate material must be solved. In this paper, we investigate one useful task of using Si as substrate with SiC buffer layer grown by carbonization of the Si surface and germanium (Ge) incorporation. The optimization of the GaN/SiC/Si structure is achieved by using an approach based upon the elasticity theory of strained interfaces. This approach provides a strain-dynamics relationship implying buffer layer composition-dependent parameters. By optimizing this composition, we can provide a theoretical basis for further investigations on the GaN/SiC/Si system based on the buffer layer technique.

In this work, we apply a theoretical method based on the elasticity theory to the optimization of heterointerfaces. The essential idea of the theory is based on the relationship between strain gradient and dynamics as shown by elasticity theory equations which enable to identify the S factor - S=f(c(ij))/rho, where f(c(ij)) are the effective elastic constants and rho the density - as an important parameter of the theory. This theory is then applied to several heterosystems.

In this work, we propose a strategy for the optimization of the SiC/Si structure as a subsequent substrate to grow aluminium nitride (AlN) layers on Si. Several routes are investigated within the framework of a theoretical approach which we recently developed and which has proved itself to be very useful in many aspects of the physics of heteroepitaxy. In this paper, we investigate one useful task of using Si as substrate with SiC buffer layer which may be grown by carbonization (C) of the Si surface. Germanium (Ge) incorporation is also modelled. The AlN/SiC/Si structure is theoretically optimized by determining the composition out of C and Ge of the buffer layer.

In this work, we present a methodology which enables to optimize the composition x of (AIN)(x)(SiC)(1-x) buried layers implanted in 6H-SiC host material. Our approach is based on the elasticity theory of strained interfaces which successfully predicts the formation of stable phases induced by epitaxial strains as well as their composition. In the investigated system, the two parent materials of the (AIN)(x)(SiC)(1-x) solid solution are AIN and SiC. The used elastic properties of these two host materials take account of the specific implantation method as a perturbative method inducing local modifications into the SiC matrix. The optimization procedure involves fitting of two parameters associated with the (AIN)(x)(SiC)(1-x)/6H-SiC interface structure, namely (i) the elastic-constant, density-related parameter S and (ii) the geometric parameter n(S). When these parameters fulfill continuity and inter-phase pseudomorphism conditions, respectively, an optimal composition is determined, in agreement with experimental results. (C) 2001 Elsevier Science B.V All rights reserved.

We present a methodology based on the elasticity theory of strained interfaces to optimize semiconductor heterointerfaces. For GaN heteroepitaxy, an alternative to sapphire substrate can be provided by SiC, which offers a better lattice matching and closer thermal expansion properties. The choice of AlN as an optimizing buffer layer material is interesting because AlN and SiC have similar physical properties. We have recently shown that the evaluation of host materials for heteroepitaxy must be based not only on geometric parameters of the host materials, but also on such parameters involving dynamics and interface strain features as identified from the equations of the elasticity theory which correlates lattice dynamics and strain gradients via the effective elastic constants and atomic density parameters (S factor) of the host materials. We demonstrate that, when AlN is used as a buffer layer, the heteroepitaxy of GaN can be optimized. These theoretical results show that the SiC-substrate alternative with the use of AlN, is a valuable approach for optimizing GaN heteroepitaxy.

In this paper, we discuss the validity of the S-correlated theory of misfit-induced interface superstructures (MIIS) and nucleation centers for misfit dislocation network (NCMDN) by comparing its results with (i) those obtained by a fully self-consistent numerical approach and (ii) available experimental results. Two main properties play an important role in the theory. The first one is the strain related S factor, which is the ratio of a linear function of the elastic constants over the material atomic density: this factor can be identified from the standard equations of the elasticity theory which, in our approach. represents the basic background. This implies a realistic lattice dynamic's model which enables to interpret the velocity of longitudinal, transverse and shear vibrational waves in solids. The second property, ns, is a geometrical parameter related to the extension of MIIS and to the lattice spacing of misfit dislocation network (MDN). We then apply this theory to several hetero-systems and we demonstrate that it can be used to optimize heterointerfaces between host materials characterized by large lattice mismatch.

In this article, we present the basic formalism of the S-correlated theory of misfit induced interface superstructures (MIIS) and nucleation centers for misfit dislocation network (NCMDN). Two main properties play an important role in the theory. The first one is the S factor, which is the ratio of effective elastic constants over the material atomic density: this factor can be identified from the standard equations of the elasticity theory which, in our approach, represents the basic background. This implies a realistic lattice dynamics model which enables to interpret the velocity of longitudinal, transverse and shear vibrational waves in solids. The second property, n(S) is a geometric parameter related to the extension of MIIS and to the lattice spacing of misfit dislocation network (MDN). We then apply this theory to several heterosystems and we demonstrate that it can be used to optimize heterointerfaces between host materials characterized by large lattice mismatch. (C) 2000 Elsevier Science B.V. All rights reserved.

Modem growth techniques are currently carried out to elaborate the cubic phase of BN films. However, c-BN growth optimization is still a question under debate. Up to now a variety of substrates has been tested and an optimized choice still remain to be found. In this work, we discuss the existing data on c-BN content in BN films in function of substrate hardness and film/substrate lattice parameter mismatch and we identify, within the framework of the elasticity theory, an elastic constant-related material feature which enlightens substrate effects in c-BN growth processes.