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Synthetic jets are jets generated by the periodic oscillation of an actuator,such as a loudspeaker, a piezoelectric membrane or a piston inside a cavity provided with an orifice or a nozzle. The fluid dynamic characteristics of the impinging synthetic jet flow field and the related heat transfer performances are strongly influenced by the waveshape of the electric signal driving the actuator. Therefore, two different classes of waveshapes have been considered: those obtained by varying the suction duty cycle factor and those obtained as Fourier series at a specified fundamental frequency

The current work deals with the global dynamics of 2D stochastic tidal equations in a highly heterogeneous environment. With the help of the stochastic version of the sigma-convergence method in conjunction with the Prokhorov and Skorokhod compactness theorems, we prove that the dynamics at the macroscopic level is of the same type at the microscopic level, but this time with non oscillating parameters. We also prove a corrector-type result.

This work presents a comparison of the results from an experimental and numerical investigation of impinging swirling jets operating at Reynolds number and swirl number equal to 30’000 and 0.61, respectively. Measurements are carried out via InfraRed Thermography using a heated thin foil as heat flux sensor, varying the impingement distance from 1 to 10 nozzle diameters. Numerical simulations of the same configurations are performed with a commercial software (Ansys Fluent) to test the capability of different Reynolds-Averaged Navier-Stokes (RANS) equations-based turbulence models in predicting the heat transfer rates from wall to the swirling impinging jets.

Synthetic jets are zero-net mass flux flows that have been recently used in a wide range of flow control applications, among which the control of bluff body wakes. An optimal control is based on an appropriate tuning of the involved parameters, which implies knowledge of the effects of such parameters on the flow field. The present work reports on an experimental investigation of the active open-loop control of a cylinder wake at Reynolds number equal to 4600 using a slot synthetic jet located at the rear stagnation point. Three values of f+ (0.49, 0.98 and 1.96) are considered and, for each of them, Cµ is varied among as many different values (5.4%, 10.8% and 21.6%) for a total of five investigated Reynolds numbers ratio R (1.0, 2.0, 4.0, 8.1 and 16.4). The flow field in the cylinder wake is found to be highly sensitive to the variations of f+ and Cµ. By increasing Cµ. and/or f+ the extent of the time-mean recirculation region is observed to decrease. Furthermore, the cylinder wake can exhibit a symmetric or an asymmetric behavior depending on the R. Indeed, at high Reynolds numbers ratio R, the cylinder wake shows a symmetric behavior because of a strong synthetic jet which stops the evolution of the shear layer instability leading to a synchronization of the vortex shedding with the synthetic jet Differently, at low R, the evolution of the cylinder wake shows the classic asymmetric behavior.

We consider an elliptic operator in a planar waveguide with a fast oscillating boundary where we impose Dirichlet, Neumann or Robin boundary conditions assuming that both the period and the amplitude of the oscillations are small. We describe the homogenized operator, establish the norm resolvent convergence of the perturbed resolvent to the homogenized one, and prove the estimates for the rate of convergence. It is shown that under the homogenization, the type of the boundary condition can change.

Steam assisted pyrolysis could represent a valuable technique of processing mixed herbaceous biomass wastes for both matter and combustion based energy recovery. The set-up of efficient and sustainable technologies exploiting steam pyrolysis to this aim requires both the definition of optimal operating conditions and the build up of a well-established corpus of knowledge on the effects of these conditions and of feedstock composition and preparation on final products and overall energetic balances. To this aim a multi-plate laboratory reactor has been realized and a systematic experimental work is currently carried out. Methodology of this approach is here briefly discussed in relation to the peculiar design of the test reactor that allows for realization of steam pyrolysis of biomasses quantities, under quasi-kinetic controlled conditions, enabling a thorough quantitative characterization of gaseous, liquid and solid products yields and characteristics otherwise impossible in standard thermogravimetric systems. One of the key points of the proposed methodology is the exploitation of a systematic exploration of pyrolysis process of elementary biomasses constituents. In the present paper thermal analysis of cellulose degradation, aimed at evaluate influence of pressure on cellulose degradation in terms of products yields and gas composition in the range 2-5bar, is reported and compared to TGA experiments in order to test the reactor performances in terms of thermal control.

Three tunnels for hydraulic purposes were excavated by tunnel-boring machines (TBM) in mostly hard metamorphic rocks in Northern Italy. A total of 14 km of tunnel was surveyed almost continually, yielding over 700 sets of data featuring rock mass characteristics and TBM performance. The empirical relations between rock mass rating and penetration rate clearly show that TBM performance reaches a maximum in the rock mass rating (RMR) range 40–70 while slower penetration is experienced in both too bad and too good rock masses. However, as different rocks gives different penetrations for the same RMR, the use of Bieniawski's classification for predictive purpose is only possible provided one uses a normalized RMR index with reference to the basic factors affecting TBM tunneling. Comparison of actual penetrations with those predicted by the Innaurato and Barton models shows poor agreement, thus highlighting the difficulties involved in TBM performance prediction.

The aims of this study were to evaluate the clinical usefulness of magnetic resonance myelography (MR-M), to suggest technical improvements and to evaluate the results obtained by comparing them with conventional MRI and conventional myelography. A series of 14 healthy volunteers and 43 patients with myelinic or radicular disease were studied by conventional MR and MR-M on an 0.5T unit using sequences pre-optimized for the acquisition of myelographic images. MR-M did not modify the diagnosis made by conventional MRI in cases of myelinic or radicular compression, but it did provide useful additional information in 38% of cases. It provided no additional information on compressive disease. Similar results in terms of quality of information were obtained from the correlation with conventional myelography. In our opinion, MR-M is useful only for cases of discal or spondylogenetic disease.

Steam assisted slow pyrolysis is studied for the processing of vegetal waste for both energy and matter recovery through the production of a vapor phase fuel, highly diluted in steam, and biochar. Arundo Donax leaves has been investigated as possible low cost feedstock given the low agronomic inputs needed to its growth and its high productivity also in marginal lands located in Mediterranean to sub- tropical environments.

Synthesis and characterization of a new gold-2-mercapto-1-methyl imidazole are reported. This new organic material shows an extraordinary fluorescence activity (superfluorescence) up to 220°C with an unusual quantum yield of 0.2. Both fluorescence andNMRspectroscopywere applied to understand the behavior of the gold-2-mercapto-1-methylimidazole complex. Results suggest that the superfluorescence activity can be attributed to the shrinking of the HOMO-LUMO band gap energy following complexation of the organic imidazole system with gold.

Natural convection heat transfer is of a great interest in a lot of industrial applications: nuclear technologies, electronic circuit board cooling and many other fields. Only few studies have been carried out to determine the effect of surface roughness or shape on natural convective laminar flow. In this paper the effect of periodic patterns of protrusions (ribs) on the freeconvection heat transfer in a vertical plate, with uniform heat flux rate boundary condition, is experimentally investigated. The convective fluid is air. Heat transfer measurements are performed by using the infrared thermography and the heated thin foil technique

Gold nanoparticles of regular shape have been obtained by thermal decomposition of AuSC12H25 molecules dissolved in different amorphous polymers. In particular, the formation of triangular nano‐platelets has been observed using poly(vinyl acetate) and poly(methyl methacrylate) as particle growth medium. Whereas, when polymers with less‐bonding side‐groups were used (e.g., poly(vinyl alcohol), polystyrene), the gold nanoparticles did not develop a regular shape during their growth.

Aim of our study is to present the findings of parietal cortex alterations in patients affected by movement disorders. We observed 4 patients with movement disorders (3 parkinsonian syndromes, I diffuse dystonia) and MR evidence of cortical alterations, without additional cerebral lesions. MR was performed with a 0.5T unit, SE T1-w, TSE T2-w, and Turbo Fluid Attenuated Inversion Recovery (T-FLAIR) sequences on axial and coronal planes, contiguous slices and 5 mm slice thickness. In the parkinsonian patients, parietal atrophy was observed in 2 cases and fronto-parietal atrophy in I case; in all cases T-FLAIR sequences showed bilateral parietal cortex signal alteration. The patient with diffuse dystonia presented severe bilateral parietal atrophy with bilateral fronto-parietal signal alteration. Our findings are strongly suggestive for cortico-basal degeneration. The evidence of signal alteration within the cortex suggests a primary pathogenetic involvement of cortico-basal pathways.

Aim of this study was to evaluate the sensitivity of MR dynamic Bolus Tracking technique versus CT-cysterno graphy in Normal Pressure Hydrocephalus (NPH). Seven patients (age 64–76 yrs), clinically suspected of NPH, were retrospectively evaluated. They had been submitted to CT-cysternography, MR dynamic Bolus Tracking technique in the acqueduct (cardiac-gated flow direction evaluation by means of 12–16 FFE T2*-w acquisitions per cardiac cycle, on sagittal plane along the acqueduct, with presaturation perpendicular to the acqueduct) and finally to surgical evaluation and subsequent ventriculo-peritoneal shunt. MR showed in all cases altered cerebrospinal fluid (CSF) dynamics: 5 patients showed CSF reflux in the third ventricle during all cardiac cycle, in 2 patients an increased ejection rate through the acqueduct and into the cisterna magna was found. CT-cysternography showed CSF dynamics alterations only in 4 cases. MR dynamic Bolus Tracking technique has proven to be more sensitive than CT-cysternography in the evaluation of NPH. Even though this study has to be considered preliminary, we believe that this simple and noninvasive technique should be recommended when NPH is suspected.

The common-reflection-surface (CRS) stack is a macro-model independent seismic reflection imaging method that has proved to accurately detect and characterise meaningful events in the pre-stack data. As any 3D data-driven method, it requires an azimuthal distribution of traces as uniform as possible, in order to properly infer necessary information from the data. Its application to 3D datasets with narrow-azimuth acquisitions requires some simplified assumptions of the underlying theory. We present an approximated formulation and a related processing method that still represents an improvement with respect to conventional techniques currently employed. The advantages of the method when performing stacking velocity analysis are demonstrated on a synthetic example

The role of magnetic resonance (MR) imaging in the evaluation of renal pathologies is becoming increasingly important. MR imaging is now con-sidered a modality complementary to computed tomography (CT) and ultrasound (US). Using up-to-date equipment, it is possible to obtain high-quality images of the kidneys and perirenal spaces; MR imaging provides information particularly useful for the staging of renal neoplasms. The use of fast imaging techniques may also provide information regarding renal function and allow for selective direct imaging of the upper urinary tract.

We compared GRE T1 3D FS sequence with other acquisition techniques available on medium field strength MR units (.5 T) in patellofemoral cartilage studies.The imaging protocol scheduled Spin Echo (SE), Inversion Recovery (STIR), Gradient Echo (GRE), Turbo Spin Echo (TSE), Turbo-Inversion Recovery (Turbo-STIR), Gradient Spin Echo (GRASE) and Echo Planar (EPI) sequences, in some cases combined with Fat Suppression (FS) or Magnetization Transfer Contrast (MTC) sequences when suitable. In vitro studies were carried out for signal-to-noise ratio (SNR) evaluation, and in vivo on 10 healthy volunteers for contrast-to-noise ratio (CNR) evaluation between cartilage, bone marrow and fluid. The exams were carried out on MR equipment operating at .5 T, with 15 mT/m power gradients.In both in vitro and in vivo studies, GRE T1 3D FS sequences yielded better results in SNR and CNR than other sequences. The GRE T1 3D FS technique combines the advantages of the increased resolution of 3D images with the increased dynamic range of fat suppressed images, for better CNR between cartilage, fluid and bone marrow.GRE T1 3D FS sequences are the MR acquisition technique of choice in the assessment of the hyaline cartilage of the knee, even at medium field strength.

The conventional Spin-Echo sequences have been the most used acquisition techniques on Magnetic Resonance Imaging (MRI) of the brain, since the beginning of 1990s. Recently, however, technological developments proposed such new fast acquisition techniques, with a dramatic reduction in acquisition time as Gradient Echo, Turbo Spin Echo, Gradient Spin Echo ed Echo Planar sequences. We investigated the comparative adequacy of the new fast sequences, in brain MR studies versus conventional sequences, on medium field strength MR equipment (.5 T). On in vitro exams S/N ratio was evaluated and on in vivo study C/N ratio between white substance grey substance and fluid were evaluated, in 15 healthy volunteers. All the exams were carried out on Philips NT5 Gyroscan MR unit operating at .5 T, with 15 mT/m power gradients. Both conventional and fast sequences Spin-Echo (SE), Inversion Recovery (IR), Gradient-Echo (GE), Turbo Spin-Echo (TSE), Gradient Spin-Echo (GRASE) and Echo Planar (EPI), all optimized to obtain T1, T2 and T1-IR weighted images, were performed. The sequences were evaluated separately comparing different acquisition techniques relative to the same type of contrast (T1, T2, and T1-IR). The results indicate the superiority of the fast acquisition techniques, both in terms of quality and acquisition times, except for T1-weighted images, where the conventional Spin-Echo sequences confirmed to be superior. In conclusion, the present study suggests that fast acquisition techniques can improve the conventional protocol of sequences, in the anatomical representation of the normal brain even with medium field strength equipment only on T2 and T1-IR weighted images. On T1-weighted imaging conventional SE acquisition technique is still the best choice. The time saving obtained with fast sequences can therefore be used for an overall improvement in the quality of images, and to apply accessory acquisition plans on routine exams.

The anencephaly is a congenital malformation, characterized by the absence of the cerebral structures and of the skull. In this study we have considered 5 cases of anencephaly, occurred in the decade 1985-1994. All the pregnant women have been interviewed and underwent ultrasonographic evaluation. Four out of 5 pregnant women have voluntarily interrupted pregnancy. In only 1 case, having achieved woman the 40th week of pregnancy, the delivery has been spontaneous: the fetus has died after few hours. The results of this study suggest that, being the anencephaly the most commonly indications for the abortion, would be important to help the women bearers of anencephalic fetuses to consent taking the organs, using them for transplantations on children that necessitate them.

In the last decade, magnetic resonance imaging (MRI) has played the main role in the study of diseases affect­ing the central nervous system (CNS). The main limita­tions of the first commercial units were predominantly represented by long acquisition times and low spatial resolution. The dramatic technological developments of the 1990’s have made it possible to overcome these lim­itations by selectively enhancing each parameter influ­encing the magnetic resonance (MR) signal, and have paved the way to functional studies with medium field units.

A clinical case of cervical carcinoma Stage Ib is described. We treated a 48-year old woman with grade 2 carcinoma, using cisplatin at a dose of 40 mg/mq on the 1st and 4th days, bleomycin at a dose of 15 mg/mq on the 1st and 8th days, and anti-emetic for two cycles. On the basis of the low ratio T4/T8 we also administered along with chemotherapy, alpha natural interferon at a dose of 3,000,000 i.u. three times a week for four weeks. At the end of the chemotherapeutic treatment the lesion was reduced in size and the biopsy was pathognomically of a microinvasive cancer. In spite of the encouraging biopsy results, the patient was submitted to a simple hysterectomy, with random lymphoadenectomy. Today, two years after her treatment, the patient is free of disease. At present there is discussion as to the efficacy of neoadjuvant chemotherapy in the first stages of the neoplasia in relation to conventional treatment, which reserves chemotherapy to stages IV and IVb and to relapses, in the light of both the lesion and the disposability of the patient to treatment and successive follow-up.

The aims of the present study are to obtain detailed surface flow visualization and convective heat transfer measurements nearby a 180deg sharp turn in a square channel, and to prove that the use of infrared thermography may be appropriate to experimentally study this type of problems. Surface flow visualization and heat transfer measurements are performed by means of the heated-thin-foil technique and results are presented in terms of temperature maps and Nusselt number Nu distributions. Nu is computed by means of the local bulk temperature. The Reynolds number, based on average inlet velocity and hydraulic diameter of the channel, is varied between 1.6x104 and 5.5x104.

All phases of HPV infection are under the control of the immunitary system which is probably inhibited by the virus itself. We studied 65 patients (range 22-55 year). They presented an HPV vulvovaginal infection not healed after common therapy. The aim of our study was to verify the changes occurring in the immune system during HPV vulvo-vaginal infection. Using the immunohistochemical method we evaluated the number of T4,T8 and NK lymphocytes inside the lesion. Moreover we measured the immunitary cells of the hematic compartment. Inside the lesion we noted a reduction of the immune system in 69.23% of cases, while in the hematic compartment it was reduced only in 6.15% of cases. These data strongly suggested that the evaluation of the immunitary state, before starting therapy, is important in deciding when it would be useful to associate immunostimulating substances at the common treatment of vulvo-vaginal infection.

Until few years ago, MR assessment of pancreatic carcinoma was thought to be feasible only with high-strength equipment, but today also low- and midfield units allow pancreatic lesion detection, thanks to parameter optimization. The authors retrospectively analyzed the MR findings of 57 patients examined with a midfield MR unit; all the patients had clinically suspected pancreatic carcinoma, which was confirmed in 54 cases. The lesions were more easily detected using T1-weighted sequences, thanks to their high intrinsic contrast, while T2-weighted sequences often confirmed the glandular changes already depicted by T1-weighted sequences. MRI correctly depicted vascular and lymph node involvement and detected liver metastases with no i.v. contrast agent injection. The only limitations of this technique are the unfeasibility of MR exams of diagnostic value in uncooperative patients (5% of cases) and the very similar MR features of parenchymal scars, due to previous acute pancreatitis, to those of pancreatic carcinoma. In conclusion, CT remains the gold standard in the study of pancreatic cancers, but midfield strength MRI, if correctly performed, can be proposed as a complementary tool to CT, especially in questionable cases and in the patients with known reactions to iodinated contrast agents.

Cervical intraepithelial lesions associated with genital human papilloma virus (HPV) infection occur with increased frequency and severity among women with immunodeficiency. In this study, we considered 24 HIV-seropositive and 12 HIV-seronegative women. Each woman was interviewed and underwent a cytologic and colposcopic evaluation. Then colposcopic and cytologic findings were correlated with histologic and differences between HIV-seropositives and seronegatives were analyzed. Ten (41%) of 24 HIV-seropositive and one (9%) of 12 HIV-seronegative women had human papilloma virus infection. Among seropositives, eight (34%) had cervical intraepithelial (CIN): of those eight, 5 had CIN I, 2 CIN II and 1 CIN III. There (24%) of the 12 HIV-seronegative had CIN: two had CIN I and one CIN II. Six of the HIV-seropositive women were found to have multicentric disease (two or more sites). The objective of this study is to determine the relationship between human immunodeficiency virus (HIV) and human papilloma virus infection, sexual habits, reproducive history, and risk of cervical intraepithelial neoplasia (CIN). The results of this study suggest that cervical intraepithelial neoplasia is a common finding in HIV-infected women. Papanicolaou tests should be effective for detecting cervical disease in this population.

Vaginal melanoma in pregnancy is a rare but extremely malignant tumour for which the prognosis is worsened by the fact that pregnancy increases the secretion of Melanocyte-Stimulating Hormone (MSH). The clinical case is described of a malignant vaginal melanoma in a 27 year-old woman in her 38th week of gestation, who was referred for slight vaginal bleeding. Clinical examination revealed a 3 cm pedunculate tumour on the anterior wall of the vagina. Vaginal cytology suggested a melanoma and instrumental examination failed to reveal any lymph node involvement. The vaginal tumour was removed during a caesarean section and subsequent histological examination identified it as a Breslow Stage II malignant melanoma. A 24-month follow-up showed the patient to have been completely cured.