Prominence of Terahertz Acoustic Surface Plasmon Excitation in Gas-Surface Interaction with Metals

The current understanding of the dynamics of gas-surface interactions is that all of the energy lost in the collision is transferred to vibrations of the target. Electronic excitations were shown to play a marginal role except for cases in which the impinging particles have energies of several electronvolts. Here we show that this picture does not hold for metal surfaces supporting acoustic surface plasmons. Such loss, dressed with a vibronic structure, is shown to make up a prominent energy transfer route down to the terahertz region for Ne atoms scattering off Cu(111) and is expected to dominate for most metals. This mechanism determines, e.g., the drag force acting on telecommunication satellites, which are typically gold-plated to reduce overheating by sunshine. The electronic excitations can be unambiguously discerned from the vibrational ones under mild hyperthermal impact conditions.

Velocity distributions in microskimmer supersonic expansion helium beams: High precision measurements and modeling

Supersonic molecular beams are used in many applications ranging from spectroscopy and matter wave optics to surface science. The experimental setup typically includes a conically shaped, collimating aperture, the skimmer. It has been reported that microskimmers with diameters below 10 μm produce beams with significantly broader velocity distributions (smaller speed ratios) than larger skimmers. Various explanations for this phenomenon have been proposed, but up till now, only a limited amount of data has been available. Here we present a systematic study of the velocity distribution in microskimmer supersonic expansion helium beams. We compare a 4 μm diameter skimmer with a 390 μm diameter skimmer for room temperature and cooled beams in the pressure range 11-181 bars. Our measurements show that for properly aligned skimmers, the only difference is that the most probable velocity for a given pressure and temperature is slightly lower for a microskimmed beam. We ascribed this to the comparatively narrow and long geometry of the microskimmers which can lead to local pressure variations along the skimmer channel. We compare our measurements to a model for the supersonic expansion and obtain good agreement between the experiments and simulations.

A modified time-of-flight method for precise determination of high speed ratios in molecular beams

Time-of-flight (TOF) is a standard experimental technique for determining, among others, the speed ratio S (velocity spread) of a molecular beam. The speed ratio is a measure for the monochromaticity of the beam and an accurate determination of S is crucial for various applications, for example, for characterising chromatic aberrations in focussing experiments related to helium microscopy or for precise measurements of surface phonons and surface structures in molecular beam scattering experiments. For both of these applications, it is desirable to have as high a speed ratio as possible. Molecular beam TOF measurements are typically performed by chopping the beam using a rotating chopper with one or more slit openings. The TOF spectra are evaluated using a standard deconvolution method. However, for higher speed ratios, this method is very sensitive to errors related to the determination of the slit width and the beam diameter. The exact sensitivity depends on the beam diameter, the number of slits, the chopper radius, and the chopper rotation frequency. We present a modified method suitable for the evaluation of TOF measurements of high speed ratio beams. The modified method is based on a systematic variation of the chopper convolution parameters so that a set of independent measurements that can be fitted with an appropriate function are obtained. We show that with this modified method, it is possible to reduce the error by typically one order of magnitude compared to the standard method.

A free jet (supersonic), molecular beam source with automatized, 50 nm precision nozzle-skimmer positioning

Low energy (thermal) free jet (supersonic) molecular beams are used in a range of applications from surface science and surface deposition to quantum coherence and gas kinetics experiments. A free jet molecular beam is created by a gas expansion from a high pressure reservoir through a small aperture (nozzle). The nozzle typically has a diameter of 2-20 μm. The central part of the beam is selected using a skimmer, typically up to 500 μm in diameter. Recent years have seen the introduction of highly spatially confined beam sources based on micrometer skimmers and micrometer or even sub-micrometer nozzles. Such sources have been applied, for example, in the investigation of superfluidity and in neutral helium microscopy. However, up till now no source design allowing the precise positioning of the micro-skimmer relative to the nozzle has been available. This is an important issue because the relative position of skimmer and nozzle can influence the beam properties considerably. Here we present the design and implementation of a new molecular beam source, which allows an automatized, 50 nm precision positioning of the skimmer relative to the nozzle. The source is liquid nitrogen cooled and the temperature can be controlled between 110 K and 350 K with a temperature fluctuation of less than ±0.1 K over several hours. Beam intensity measurements using a 5 μm nozzle and a skimmer 5 μm in diameter are presented for stagnation pressures po in the range 3-180 bars. A 2D beam profile scan, using a 9.5 μm skimmer and a 5 μm nozzle is presented as a further documentation of the versatility of the new design and as an illustration of the influence of the relative skimmer-nozzle position on the beam properties.

Hyperthermal molecular beam deposition of highly ordered organic thin films

We use a seeded supersonic molecular beam to control the kinetic energy of pentacene (C22H14) during deposition and growth on Ag(111). Highly ordered thin films are grown at low substrate temperatures (approximately 200 K) at kinetic energies of a few electron volts, as shown by low energy He diffraction and x-ray reflectivity spectra. In contrast, deposition of thermal molecules yields only amorphous films. Growth at room or higher temperature substrates yields films of poorer quality irrespective of the depositing beam energy. We find that after the first wetting layer is completed, a new ordered phase is formed, whose in-plane lattice spacings match one of the bulk crystal planes. The high quality of the films can be interpreted as the result of local annealing induced by the impact of the impinging high-energy molecules.

Dynamics of tearing modes during strong electron cyclotron heating on the FTU tokamak

The localized electron cyclotron resonance heating power that can suppress sawteeth reconnection often drives m = 2 tearing modes in a tokamak operating at constant current. The dynamics of mode onset and coupled mode evolution is described in detail and compared with a nonlinear theoretical model that identifies the effects of mode coupling, finite inertia of the rotating islands, and wall braking.

Estroprogestin vs. gonadotrophin agonists plus estroprogestin in the treatment of endometriosis-related pelvic pain: a randomized trial. Gruppo Italiano per lo Studio dell'Endometriosi

OBJECTIVE

This is a randomized clinical trial comparing estroprogestin (E/P) pill given for 12 months vs. gonadotrophin releasing hormone agonist (GNRHa) given for 4 months followed by E/P pill treatment for 8 months in the relief of endometriosis-related pelvic pain.

METHODS

Eligible for the study were women with laparoscopically confirmed endometriosis and pelvic pain lasting 3-12 months after diagnosis. Eligible women were randomly assigned to treatment with E/P pill (gestroden 0.75 mg and ethynlestradiol 0.03 mg) for 12 months (47 patients) vs. tryptorelin 3.75 mg slow release every 28 days for 4 months followed by E/P pill for 8 months (55 patients).

RESULTS

At baseline, dysmenorrhea was reported in 46 women allocated to E/P pill only (97.9%), and in all the 55 women allocated to GNRHa+E/P pill. The corresponding value at the 12 months follow-up visit was 14 subjects (35.9%) and 16 subjects (34.8%). The baseline median values of the multidimensional and analog scale were for dysmenorrhea 4 and 6 in the EP only and 3 and 6 in the GNRHa+E/P group. The corresponding value at the 12 months follow-up visit were 2 and 6 and 0 and 5. Non-menstrual pain was reported, respectively, at baseline and 12 month visit by 46 (97.9%) and 15 (38.5%) subjects in the E/P pill group and 49 (89.1%) and 17 (37.0%) of the GNRHa+E/P pill one. The baseline median values of the multidimensional and analog scale were for non-menstrual pain 3 and 5 in the E/P only and 2 and 6 in the GNRHa+E/P group. The corresponding values at the 12 month follow-up visit were 0 and 4 and 0 and 4. These differences between the two groups were not statistically significant.

CONCLUSIONS

1 year after randomization, the two treatment schedules show similar relief of pelvic pain in women with endometriosis.

Testosterone maintenance therapy. Effects on vulvar lichen sclerosus treated with clobetasol propionate

OBJECTIVE

To evaluate the possible effects of topical testosterone as maintenance therapy after clobetasol propionate treatment.

STUDY DESIGN

Thirty-two patients with biopsy-proven vulvar lichen sclerosus (LS), after 24 weeks of treatment with 0.05% clobetasol propionate cream, were randomly distributed into two groups of 16 each and treated for a further length of time (24 weeks) with testosterone 2% ointment or a cream-based preparation (placebo). The patients were examined before and after treatment for symptoms, gross aspects and histologic features.

RESULTS

With clobetasol propionate all patients had a marked improvement (P < .001) in both clinical and histologic parameters. After clobetasol propionate therapy, the 16 testosterone-treated patients had significant worsening of their symptoms (P < .05%) and no evident changes in gross aspects (P = NS). The placebo-treated group had good symptomatic control of their disease, with no significant changes in symptoms or gross aspects (P = NS).

CONCLUSION

After the good results obtained with clobetasol propionate, treatment with testosterone appeared to have a negative effect, while a regularly provided emollient cream was useful in symptom control.

Vulvar lichen sclerosus. Immunohistologic evaluation before and after therapy

In 20 women with vulvar lichen sclerosus (LS) we analyzed the immunohistologic features of the dermal lymphoid infiltrate and the number of epidermal CD1a+ cells (Langerhans cells). Activated (HLA-Dr+) T cells, associated with CD1a+ accessory cells, were found in the dermis in all cases. The number of CD1a+ epidermal cells was increased, and the cells expressed strong HLA-DR+ staining. These findings suggest activation of the skin immune system in vulvar LS lesions. Conventional 2% testosterone therapy failed to modify the immunohistologic features. Clobetasol, 0.05%, application seemed more effective in down-regulating the skin's immune system activation profile.

[Nosocomial infections caused by methicillin-resistant Staphylococcus aureus in a pediatric intensive care unit]

We performed an epidemiological investigation owing to the appearance between February and March 1988, of subsequent MRSA infections in our ICU; we also started a checking scheme. At the same time we performed a retrospective-perspective study of 701 patients (310 newborns 391 not newborns) admitted into ICU from 1-1-1987 to 30-6-1988. This study allowed us to settle the presence of MRSA in ICU and the manner in which they become infected. From our study the 4.9% of our patients contracted hospital infections and the 34.2% of these were MRSA infections. The 39.7% of our colonized patients were MRSA. It is really significant the frequency of MRSA colonization (p less than 0.0005) among newborn patients compared with other age patients; in the meantime there is not statistical significance in the frequency of MRSA hospital infections among the two groups. The results of our study show that infections were probably transmitted by the hands of the members of staff and that the reservoir of MRSA are tracheostomized hosts or long term ventilated patients.

Immunohistochemical evidence of skin immune system involvement in vulvar lichen sclerosus et atrophicus

Biopsies taken from vulvar lesions in 12 women affected by vulvar lichen sclerosus et atrophicus (LSA) have been processed for immunohistological study. Activated (HLA-Dr+) T cells, associated with CD1a+ accessory cells, were found in the dermis in all cases, with architectural patterns varying in relation to the histological phase (early, well developed, old) of the lesion. Interestingly, the number of epidermal CD1a+ Langerhans cells (LCs) was increased in all cases, without any correlation with the amount of the dermal infiltrate and with the histological phase of the lesions. In fact, also in old lesions the number of epidermal CD1a+ LCs was increased, and the sparse dermal lymphoid cells showed a persistent HLA-Dr antigen expression. These data, indicating the persistent activation of epidermal antigen-presenting cells and lymphoid cells in all the evolutive phases of vulvar LSA, suggest a possible involvement of the skin immune system in the pathogenesis of LSA.

[The relationship between ligation of the ductus arteriosus and intracranial hemorrhage in preterm infants]

Surgical closure of patent ductus arteriosus (PDA) and perioperative time have been proposed as conditions of increased risk of peri-intraventricular hemorrhage (PVH-IVH) in preterm infants. We examined by pre- and postoperative ultrasound (US) scan 15 low birth-weight neonates who underwent PDA ligation within the first two weeks of life. They were assessed with regard to clinical state, perioperative management and development of PVH-IVH. Fourteen did not show onset or extension of intracranial hemorrhage in the immediate postoperative period. One patient developed a wide III grade IVH in the 24 perioperative hours. His conditions were particularly severe, suggesting that many factors such as acidosis, hypoxia, hypercapnia and hypotension might have combined to lead to hemorrhage. We conclude that PDA ligation is not likely to increase the risk of PVH-IVH per se.

[Role of Mycoplasma hominis in acute infections of the female genital system]

A study was carried out on the role of mycoplasma hominis in obstetric and gynecological infections, and the paper reports a case report of acute pelvoperitonitis in a woman fitted with an IUD. The important role of early preoperative diagnosis in underlined and the current criteria for correct antibiotic therapy are discussed.

[The use of automatic injectors in hysterosalpingography]

The paper describes 168 cases of HSP in which a low-pressure automatic injector, as is normally used in angiography, was used to inject the contrast medium and controlled from the booth of a remote-control X-ray device. Having analysed the clinical indications for this X-ray method, the paper stresses the advantages for the patient, in the form of a lower dose of irradiation and a shorter duration of the test in comparison to traditional methods of manual injection of the contrast medium, and for the operator who is completely protected from irradiation.

[Surgical stress and anesthetic protection]

Surgical pain triggers a series of neuro-endocrine change in the patient's organism both during the operation and at the post-operative stage, exposing the patient to a parapathological and quite afinalistic situation. It is the task of anaesthesia to prevent these adaptation reactions setting in or at least to attenuate them. Various anaesthesiological techniques are compared and results are examined with a view to establishing what technique is capable of procuring most anaesthesiological "protection".

A case of acid lipase deficiency: Wolman's disease

We report a case of Wolman disease, an unusual autosomal recessive disease characterized by storage of lipid in histiocytes. Storage of cholesteryl esters and triglycerides is caused by lysosomal acid lipase deficiency. This enzyme hydrolyses the cholesteryl esters of LDL thus allowing their peripherical metabolism. Onset of the disease occurs after the first month of life with hepatosplenomegaly, diarrhea, vomiting, abdominal distension, failure to thrive. Diagnosis, suspected because of calcifications of the adrenals was achieved by demonstration of lysosomal acid lipase deficiency in lymphocytes and cultured skin fibroblasts. Carriers of the disease can be identified by enzyme assays in lymphocytes and fibroblasts and prenatal diagnosis can be accomplished by lysosomal acid lipase assays in cultured amniotic fluid cells and chorionic villi.

Two mutations of dihydropteridine reductase deficiency

Two patients with dihydropteridine reductase (DHPR) deficiency, in one case due to the absence of any enzyme protein (DHPR- cross reactive material (CRM)-) and in the other case due to the production of a mutant type devoid of catalytic activity (DHPR- CRM+) were examined. This latter form of malignant phenylketonuria, whose relative frequency seems to be higher in the Italian population, possibly has a worse prognosis. The earlier onset and the greater severity of clinical symptoms are associated with a more pronounced hydroxylation defect, as shown by higher degree of neonatal hyperphenylalaninaemia, unresponsiveness to an oral tetrahydrobiopterin load, lower concentrations of neurotransmitter metabolites, and reduced tyrosine production after an oral phenylalanine load.

[Trial of indirect screening of tetrahydrobiopterin deficiency]

The possibility of an early diagnosis of tetrahydrobiopterin deficiency among hyperphenylalaninemic infants, when specific screening tests cannot be performed, was evaluated. Three tetrahydrobiopterin deficient patients, two with dihydropteridine reductase deficiency and one with dihydrobiopterin synthetase deficiency were examined together with their parents and compared with twelve phenylketonuric patients, their parents and sixteen normal subjects. The parameters considered in the hyperphenylalaninemic patients (degree of neonatal hyperphenylalaninemia, phenylalanine lowering speed in response to a restricted diet, dietary tolerance to phenylalanine, oral phenylalanine load) were found to be insufficiently or lately indicative. By contrast, heterozygosity tests (molar ratio (Phe)2/Tyr and sigma discriminant function) performed on the parents allowed a suspicion of tetrahydrobiopterin deficiency, the definite diagnosis being of course based upon specific investigations.

Tetrahydrobiopterin non-responsiveness in dihydropteridine reductase deficiency is associated with the presence of mutant protein

Correlation of the response to a load of tetrahydrobiopterin (BH4) in dihydropterin reductase (DHPR) deficient patients to the type of mutation in these patients has led to the conclusion that 4 patients without mutant DHPR molecules in their cells respond to the BH4 load, whereas 3 patients with mutant DHPR in their cells do not respond. Intravenous injection of BH4 in 1 of the cases not responding to BH4 again showed no response.