Calibration of thermocouple-based scanning thermal microscope in active mode (2ω method)

We present a procedure dedicated to the calibration of a scanning thermal microscopy probe operated in an active mode and a modulated regime especially for the measurement of solid material thermal conductivities. The probe used is a microthermocouple wire mounted on a quartz tuning fork. Measurements on reference samples are performed successively in vacuum and ambient air conditions revealing a clear difference in the dependence of the thermal interaction between the probe and the sample on the sample properties. Analytical modeling based on the resolution of the heat equation in the wire probe and a description of the thermal interaction using a network of thermal conductances are used to fit experimental data and analyze this difference. We have experimentally verified that the effective thermal contact radius of the probe tip depends on the sample thermal conductivity in ambient conditions, whereas it remains constant in vacuum. We have defined the measurement range of the technique based on the decrease in the probe sensitivity at high thermal conductivities. Considering the experimental noise of our electrical device, it is shown that the maximum measurable value of thermal conductivity is near 23 W m^-1 K^-1 in vacuum and 37 W m^-1 K^-1 in ambient air conditions. Moreover, the lowest uncertainties are obtained for thermal conductivities below 5 W m^-1 K^-1 typically.

Quantitative thermal microscopy using thermoelectric probe in passive mode

A scanning thermal microscope working in passive mode using a micronic thermocouple probe is presented as a quantitative technique. We show that actual surface temperature distributions of microsystems are measurable under conditions for which most of usual techniques cannot operate. The quantitative aspect relies on the necessity of an appropriate calibration procedure which takes into account of the probe-to-sample thermal interaction prior to any measurement. Besides this consideration that should be treated for any thermal contact probing system, the main advantages of our thermal microscope deal with the temperature available range, the insensitivity to the surface optical parameters, the possibility to image DC, and AC temperature components up to 1 kHz typically and a resolution limit related to near-field behavior.

Near-infrared thermography using a charge-coupled device camera: application to microsystems

Using near-infrared thermography microscopy and a low-cost charge-coupled device (CCD) camera, we have designed a system which is able to deliver quantitative submicronic thermal images. Using a theoretical model based on Planck's law and CCD sensor properties allowed us to determine a minimal theoretical detection temperature and an optimal temperature sensitivity of our system. In order to validate this method, we show a good relationship between a theoretical study and a thermal measurement of a microsample.

Characterization and fabrication of fully metal-coated scanning near-field optical microscopy SiO2 tips

The fabrication of silicon cantilever-based scanning near-field optical microscope probes with fully aluminium-coated quartz tips was optimized to increase production yield. Different cantilever designs for dynamic- and contact-mode force feedback were implemented. Light transmission through the tips was investigated experimentally in terms of the metal coating and the tip cone-angle. We found that transmittance varies with the skin depth of the metal coating and is inverse to the cone angle, meaning that slender tips showed higher transmission. Near-field optical images of individual fluorescing molecules showed a resolution < 100 nm. Scanning electron microscopy images of tips before and after scanning near-field optical microscope imaging, and transmission electron microscopy analysis of tips before and after illumination, together with measurements performed with a miniaturized thermocouple showed no evidence of mechanical defect or orifice formation by thermal effects.

Thermal behaviour modelling of tapered optical fibres for scanning near-field microscopy

A simple model allowing the calculation of the thermal field inside a metal-coated fibre tip is presented. The approach has been based on previous temperature measurements which operated in steady state and periodic rate. The modelhas been inspired from the general theory of heat transfer inside fins, after having divided the taper into a set of layers. The advantage of the method is the possibility to consider any taper shapes. Moreover, any kind of coating thickness and external heat transfer distributions can be considered. As a mean of comparison with some previous works, results obtained for simple configurations are presented. Then, a study of the main governing parameters provides the basic thermal behaviour analysis of optical tips and a comparison with experience is given in order to confirm the validity of our approach.

The growth of tomato (Lycopersicon esculentum Mill.) hypocotyls in the light and in darkness differentially involves auxin

Light and auxin antagonistically regulate hypocotyl elongation. We have investigated the physiological interactions of light and auxin in the control of tomato (Lycopersicon esculentum Mill.) hypocotyl elongation by studying the auxin-insensitive mutant diageotropica (dgt). The length of the hypocotyls of the dgt mutant is significantly reduced when compared to the wild type line Ailsa Craig (AC) in the dark and under red light, but not under the other light conditions tested, indicating that auxin sensitivity is involved in the elongation of hypocotyls only in these conditions. Similarly, the auxin transport inhibitor naphthylphthalamic [correction of naphtylphtalamic] acid (NPA) differentially affects elongation of dark- or light-grown hypocotyls of the MoneyMaker (MM) tomato wild type. Using different photomorphogenic mutants, we demonstrate that at least phytochrome A, phytochrome B1 and, to a much lesser extent [correction of extend], cryptochrome 1, are necessary for a switch from an auxin transport-dependent elongation of hypocotyls in the dark to an auxin transport-independent elongation in the light. Interestingly, the dgt mutant and NPA-treated seedlings exhibit a looped phenotype only under red light, indicating that the negative gravitropism of hypocotyls also differentially involves auxin in the various light conditions.

The human copper-zinc superoxide dismutase gene (SOD1) proximal promoter is regulated by Sp1, Egr-1, and WT1 via non-canonical binding sites

Human copper-zinc superoxide dismutase (Cu,Zn-SOD) participates in the control of reactive oxygen intermediate intracellular concentration. In this study, we show that phorbol 12-myristate 13-acetate (PMA) increases Cu,Zn-SOD mRNA expression within 30 min. The sequence between nucleotides -71 and -29 is essential for both basal and PMA-induced gene expression. This region includes an Sp1-binding site that is also recognized by a possible Sp1-like protein and by Egr-1 in a PMA-inducible manner. Egr-1 and two splicing variants of the Egr-related protein WT1 were able to transactivate the SOD1 promoter in co-transfection experiments. Sp1 and the possible Sp1-like proteins bind to two overlapping, but distinct sequences. However, Egr-1 and Sp1 seem to interact with two sites that are either identical or very close to each other. None of these sites fit the consensus sequences previously reported for these proteins. Analysis of various mutants of the SOD1 proximal promoter revealed that the region that binds Sp1 and Egr-1 is required for both basal and Egr-1-driven expression. Interplay between different members of the Sp1 family, Egr-1, and different splicing variants of WT1 in the SOD1 proximal promoter may provide clues about the physiological function of Cu,Zn-SOD.

[The muscular pump of the calf. Video-phlebography and simultaneous EMG]

Gastrocnemical insufficiency is a common syndrome (in modern society mainly affecting young females who have been taking the pill for several years). Often it is the starting point for superficial varicosis. The clinical diagnosis is easy, provided the doctor is informed of its symptoms. Phlebography or Duplex scan are compulsory, deciding surgical treatment. Varicose muscular veins have two different causes: avalvulation at the popliteal vein or compression by the Post. Tib. nerve. Persistent pain, deterioration of the superficial network or neuromyositis are the main reasons for deciding upon surgical treatment. The results are gratifying and lasting.

[Treatment of intractable venous ulcer]

Before describing the various treatments of these ulcers, the author discusses their etiological process. He emphasizes that superficial venous insufficiency is the result of a deep venous insufficiency which alters and deteriorate the cellular metabolism. In fact, the chronic hypertension is transmitted to the capillary network, often with irreversible consequences. The author analyzes the healing process: inflammatory phase followed after 2 weeks by the appearance of fibroblasts, wound contraction and epithelialization. The third phase, so-called stabilization phase, lasts between 6 and 12 months. The treatment varies according to the etiology. It is mostly a matter of experience in order to avoid allergenic treatments.

[My viewpoint on Psathakis' surgery]

There may be various reasons for a poor functioning of the deep veins valves: one of them is thrombosis. Hypertension progresses then in the superficial vein system and is expressed by trophic disorders: dermatosclerosis and ulcer formation. An original surgical treatment was advocated by Dr. N. Psathakis. This treatment resulted in numerous critics, especially coming from those who never tried it. This method was considered as a non-scientific because the clinical and phlebographic result was not confirmed by non invasive methods. The great advantage of this method is that it is simple, atraumatic and does not alter the normal anatomy. It consists in placing a silicone strip between the femoral vein and the superficial femoral artery. The strip is secured to the biceps muscle and the medial rectus muscle. In the absence of another simple and causal treatment, we have tried this method in approximately 200 patients. We will present our personal clinical results as well as our surgical experience.

Hearing loss due to partly impulsive industrial noise exposure at levels between 87 and 90 dB(A)

A cross-sectional epidemiological survey was carried out in a car-body workshop involving 234 workers divided into three groups according to age and noise exposure duration. Their hearing levels, determined by using a standardized audiometric testing procedure, were compared to those of a reference population not exposed to noise, to those of a population exposed to quasisteady noises at 95 dB(A), and also to ISO 1999-1987. Results reveal significant hearing loss after 9 years of exposure, greater than that from quasisteady noise exposure with the same equivalent continuous A-weighted sound-pressure level.

[Physiopathology of leg pain]

The real definition of pain, the mechanism of its genesis and the relation with its nociception are now very developed, even to the point of being extremely finely nuanced. The author explains the structure and physiopathology of the nociceptive system, the nociceptors, the role of the neurons in the posterior horn and the spinothalamic duct, and the function of the cerebral cortex. After analysing the international definition of the pain symptom, the author underlines the significance of the subjective component, suffering. There follows an analysis of the specific characteristics of superficial and deep pain (somatic and visceral), of psychical and central pain. The discriminative, affective, emotive, motor vegetative sensorial components and the psychomotor are explained. Finally the mechanism of the genesis of leg pain is examined, with emphasis on the important difference between nociceptive, neurological and projected pain.

[Venous pain]

Venous pain is exceptionally little known and is described only vaguely and imprecisely. It can be elaborated as follows: venous pain is a chronic, heteroclitic and composite pain. All venous pain is, by definition, individual and open to considerable subjectivity. Venous deficiency ends up by altering the functioning of other organs which depend on it for their metabolism. The pain which arises will, because of this, be a composite pain. The two principal types of venous deficiency are described, as well as the extremely important role played by the sense receptors which as far as possible equilibrate the circulation as it becomes more and more deficient and inefficient. The nociceptors are not apparent until late on, when the danger of destruction or tissular damage is imminent or has already begun. The author explains in detail, and in three developed stages, the progress of the degradation of the return circulation, the causes, the symptoms, and why pain appears to replace chronic discomfort.

[The problem of the perforating veins]

Any obstacle slowing down or blocking the venous return, causes hypertension, then dilatation which destroys the valves of the perforating or muscular veins. The superficial veins become flooded. A symptomatic treatment with sclerosis or stripping is not sufficient. The valve is of crucial importance and varices represent a symptom indicating a snag in the venous return. The phlebologist's role is to look for and identify the snag as well as finding a treatment.

[Aneurysm of the popliteal vein]

The authors present a saccular aneurysm of the popliteal vein. The clinical findings, the diagnosis and the operative treatment are described. The authors suggest a possible etiology for the genesis of the aneurysm. Literature is reviewed.

[Surgical anatomy of the popliteal fossa]

This communication provides accurate details of the surface anatomy of the popliteal space (french and latin nomenclature). The author describes the muscular reference points, and the relationships between arteries, veins and the internal and external popliteal sciatic nerve. This region has a variety of pathologies: dilatation of the venae comites, of the sapheno-popliteal junction, doubling of the femoral and femoro-popliteal, with aneurysmal dilatation; abnormal veins (popliteal space vein), aneurysm of the popliteal vein; multiple compression due to arterial and nerve structures.

[Importance of the external saphenous vein in pathology]

Incompetence of the internal saphenous crook is not unconditionally the cause of varices. Most frequently the dilatations begin in the calf and climb progressively towards the thigh thereby dilatating the internal saphenous vein. This is explained by the quite unique nature of the anatomy of the popliteal fossa and its relationship with its vascular and nervous content. The sciatic popliteal nerve, the external and paired saphenous veins often present structural and anatomical variations. The deep range of these veins is often badly understood and explains the lack of success after stripping, staged resection or surgical sclerosis.