"Design of a Suspension Lever Mechanism in Biomedical Robotic System"

The article discusses the design of a suspended lever mechanism with elastic elements, which is used as a safety device in a robotic system for the rehabilitation of the lower limbs. The article analyzes the existing mechanical structures of devices for rehabilitation, identifies the problems of operation, design, and safety systems and suggests a new design of the device. The process of reverse development of a lever mechanism scheme to ensure safety during rehabilitation of the lower limbs is presented. The design of the lever mechanism consists of movable levers connected by elastic elements. The device allows you to dampen the force during active rehabilitation. The power calculation of the lever mechanism in the rehabilitation system was carried out. The article addresses the issues present in the current mechanical designs with a brief discussion on the system architecture.

Water entry and fall of hydrophobic and superhydrophobic Teflon spheres

Hydrophobic and superhydrophobic solid Teflon spheres have been observed while settling in water under the action of gravity, starting from different initial conditions, and have been followed until the steady-state is reached. The superhydrophobic sphere features a nano/microtextured surface and advancing and receding water contact angles equal to, respectively, [Formula: see text] and [Formula: see text]. When impacting water from air, both spheres can entrap a conspicuous amount of air deriving from the sealing of a macro-sized air cavity formed upon impact (air cavity trapping) and standing at the rear part of the settling sphere. It is shown that this air amount, like a spindle, reduces the force coefficient exerted on the sphere, basically acting on the pressure drag. However, the air cavity trapping occurs above a critical impact velocity which for the superhydrophobic spheres is significantly lower than that pertaining to the hydrophobic one; thus a certain range of impact velocities exists at which the superhydrophobic sphere experiences a lower pressure drag and a higher mean velocity. As soon as the air cavity vanishes, the dynamics of the superhydrophobic sphere becomes indistinguishable from that of the hydrophobic one, in spite of the persistence of air within the surface micro-texture.

Alien Histocompatibility Determinants on the Cell Surface of Sarcomas Induced by Methylcholanthrene. II. in Vitro Serological Studies

In vitro serological studies were carried out in an attempt to identify the foreign histocompatibility antigens previously detected by transplantation methods on the cell surface of 2 methylcholanthrene-induced BALB/c fibrosarcomas (TZ15 and ST2). The reactivity of the anti-TZ15 and anti-ST2 syngeneic sera and of the C57BL/6J anti-TZ15 and anti-ST2 sera (the latters preabsorbed on normal BALB/c lymphoid cells) was evaluated on normal lymph node cells of C3Hf, C57BL/6J, DBA/2 and AKR strains by the complement-dependent cytotoxicity and on normal fibroblasts of C3Hf and C57BL/6J mice by the isotopic antiglobulin assay. The ability of in vitro-plated TZ15 and ST2 cells to bind BALB/c anti-C3Hf, anti-C57BL/6J, anti-AKR and anti-DBA/2 alloantisera was also examined by the antiglobulin assay. Contrary to the in vivo data, no cross-reactions were found between TZ15 and AKR normal cells, since both syngeneic and allogeneic anti-TZ15 sera were not cytotoxic to C3Hf, C57BL/6J or AKR lymphoid cells nor could BALB/c anti-C3Hf, anti-C57BL/6J or anti-AKR sera bind to TZ15 tumor cells in the antiglobulin assay. Both BALB/c anti-ST2 and C57BL/6J anti-ST2 sera were also ineffective in killing normal C3Hf, C57BL/6J, AKR and DBA/2 lymphoid cells in the complement–dependent cytotoxic assay, whereas a weak but significant binding of the syngeneic anti-ST2 serum to C57BL/6J but not to C3Hf fibroblasts was detected by the antiglobulin test. ST2 but not TZ15 cells were also able to significantly absorb the complement–dependent cytotoxic activity of a BALB/c anti-C57BL/6J but not of a BALB/c anti-C3Hf antiserum. In addition, BALB/c anti-C3Hf, anti-C57BL/6J and anti-AKR sera but not BALB/c anti-DBA/2 serum strongly bound to ST2 cells in the antiglobulin test; this binding activity was absorbed by C3Hf, C57BL/6J, AKR, and NIH but not BALB/c and DBA/2 lymphoid cells. Thus, among the cross-reactions observed in vivo between ST2 and normal cells of C3Hf, DBA/2 and C57BL/6J strains, only C57BL/6J normal antigens were detectable by serology. A new but still undefined system of alien normal antigens shared by C3Hf, AKR, C57BL/6J, NIH lymphoid and ST2 cells was revealed by the BALB/c alloantisera in the antiglobulin assay. The relationship of these findings with those previously obtained in the transplantation study with the same tumors is discussed.

Sentinel Lymph Node Detection by Lymphoscintigraphy in Malignant Melanoma

Aims and Background

Sentinel lymph node (SLN) detection is currently employed in patients with malignant melanoma (MM) to spare them unnecessary lymph node dissection.

Methods and Study Design

We investigated 241 patients (130 men and 111 women, median age, 50 years (range, 14-92)) with MM (192 before and 51 after surgical biopsy); two of them had more than one melanoma lesion. In each patient approx. 10 MBq of 99mTc Nanocoll in 0.1 mL (Nycomed Amersham Sorin; particle size range, 3-80 nm) was injected intradermally around the MM lesion or surgical scar. Dynamic acquisition was performed for 20 minutes (20 frames/min) and the study was concluded within four hours of injection. Using an external radioactive marker, the skin over the SLN was marked with China ink.

Results

294 SLNs were scintigraphically identified: 117 in the inguinal region, 147 in the axillae, four in the submandibular region, three in the laterocervical region and 23 at other sites. In two patients no drainage was detected. In 43 patients more than one sentinel node was identified. In 13 patients with lesions located in the trunk the tracer drained towards multiple lymph node stations or unexpected lymph nodes (nine cases). Histology and immunohistochemistry diagnosed MM in 25 SLNs; 19 were positive for metastasis with hematoxylin-eosin staining, five with Hmb45 and one with CD68 immunostaining. All 25 detected lymphatic basins were excised. In nine of these basins there was metastatic involvement of at least one other lymph node besides the SLN. During follow-up, which ranged from six to 86 months, metastatic disease was found in only one patient with a histologically negative SLN six months after surgery.

Conclusions

This study confirms the utility of scintigraphic SLN detection in patients with MM. In most of the cases the procedure led the surgeon to evaluate the drainage area, which is unpredictable for lesions in the trunk and may be difficult to delineate using only patent blue dye. Furthermore, in approximately 10% of cases we observed dual drainage from individual lesions, mainly those located on the trunk. We will proceed to compare the results obtained during follow-up with those of an investigational group of patients with melanoma who were not subjected to lymphoscintigraphy for SLN detection in order to obtain well-founded information on the prognostic value of this technique.

Role of the Immune System in the Growth of an Isotransplanted Urethan-Induced Lymphosarcoma

Two groups of (SWR×C57BL)F1 mice were injected subcutaneously with two quantitatively different cell suspensions from a uretan-induced thymic lymphoma of the same hybrid combination. Each of these groups was divided before the neoplastic isograft into the following sub-groups: controls, cyclophosphamide injected, X-irradiated and BCG injected mice. Percentage of takes, tumor diameters and mortality provided the parameters for the evaluation of the tumor growth. With the higher inoculum of neoplastic cells (5×105) only cyclophosphamide was effective in enhancing the take percentage 10 days after the isograft. With the smaller inoculum (5 × 103) all treatments were effective on tumor growth although the inhibitory action of BCG was not as strong as the enhancing action of the immune depressive treatments. The results are interpreted as evidence of a specific antigenicity of urethan-induced lymphoma.

Immunogenic Neoplastic Clones Derived in Vitro from an Originally Non-immunogenic BALB/c Fibrosarcoma

A non-immunogenic fibrosarcoma (SDC2), obtained by spontaneous neoplastic transformation of BALB/c fibroblasts cultured within a diffusion chamber kept in the peritoneal cavity of (BALB/c × C3Hf)F1 mice, was maintained in tissue culture for 10 passages. Three different clones were then derived from the in vitro neoplastic population. Each of the clones, the original in vivo tumor, and its in vitro line taken at the 10th passage (before cloning) were tested for the presence of individual tumor-associated transplantation antigens (TATA) by in vivo growth and excision assay. Contrary to the original SDC2 neoplasm, its in vitro line and 2 out of 3 clones (CL1-SDC2 and CL3-SDC2) were immunogenic, whereas the other clone (CL6-SDC2) displayed no immunogenicity. In addition, CL1-SDC2 and CL3-SDC2 were able to induce a reciprocal cross-protection in in vivo transplantation tests, thus showing common TATA; no cross-reactions were found between these clones and 2 other chemically-induced immunogenic sarcomas. The results suggest an antigenic heterogeneity in the original population of the nonimmunogenic SDC2 sarcoma, with the presence of antigenic but sub-immunogenic neoplastic cells.

Increased Oncogenic Effect of a Low Dose of Methylcholanthrene in Immunodepressed Mice

Two different doses of MCA were used to elicit subcutaneous sarcomas in intact vs. immunodepressed adult (C57BL/6xBALB/c)F1 female mice. Immunodepression was achieved by adult thymectomy followed by a short treatment with antilymphocyte serum (4 i.p. injections of 0.25 ml at days −1, +1, +3, +5). The lower dose of MCA (30 μg) gave rise to sarcomas in 11 of 18 intact mice, and in 17 out of 17 immunodepressed animals. No such difference was found with 150 μg of the carcinogen which induced tumors in 16 of 17 immunodepressed mice and in 17 of 17 intact counterparts. These results clearly show the importance of the dosage of MCA in visualizing the funcion of immunologic surveillance in this system of chemical carcinogenesis.

Solid pancreatic pseudopapillary tumor managed laparoscopically: A case report and review of the literature

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Solid pancreatic pseudopapillary tumors are a rare neoplasms with not well known pathogenesis.

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Imaging is not able to provide a precise diagnostic orientation. The essential role is played by surgery and histological examination.

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Immunohistochemistry shows a possible correlation between the Beta-catenin mutations or alteration of the E-cadherin and tumor development.

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Laparoscopic technique has proven to be the gold standard for the countless advantages found compared to the open technique.

Background

Solid pancreatic pseudopapillary tumors are a rare neoplasms, about 1–3% of all pancreatic neoplasms. This cancer mainly affects women between the third and fourth decade of life.

They are not well known; the molecular origins represent a low degree of malignancy, in which the complete resection is curative. We report our experience with a case report of SPT in a young man.

Presentation of case

Thirty-six years old male patient with a mass about 10 cm in the pancreatic tail and splenic ilum. After following CT and MR, the patient was subjected to surgery. Histophatological result was solid tumor pseudopapillary of pancreas with no pathological lymph nodes.

Discussion and conclusion

Solid pseudopapillary neoplasm shows histological characteristic solid and pseudopapillary proliferation. Immunohistochemistry detects, among the causes of tumor development, a correlation between the Beta-catenin mutations, alteration of the E-cadherin. In the most cases, therapy is surgical treatment with laparoscopic.

Effect of drop volume and surface statistics on the superhydrophobicity of randomly rough substrates

In this paper, a simple theoretical approach is developed with the aim of evaluating shape, interfacial pressure, apparent contact angle and contact area of liquid drops gently deposed on randomly rough surfaces. This method can be useful to characterize the superhydrophobic properties of rough substrates, and to investigate the contact behavior of impacting drops. We assume that (i) the size of the apparent liquid-solid contact area is much larger than the micromorphology of the substrate, and (ii) a composite interface is always formed at the microscale. Results show apparent contact angle and liquid-solid area fraction are slightly influenced by the drop volume only at relatively high values of the root mean square roughness h _rms, whereas the effect of volume is practically negligible at small h _rms. The main statistical quantity affecting the superhydrophobic properties is found to be the Wenzel roughness parameter r _W, which depends on the average slope of the surface heights. Moreover, transition from the Cassie-Baxter state to the Wenzel one is observed when r _W reduces below a certain critical value, and theoretical predictions are found to be in good agreement with experimental data. Finally, the present method can be conveniently exploited to evaluate the occurrence of pinning phenomena in the case of impacting drops, as the Wenzel critical pressure for liquid penetration gives an estimation of the maximum impact pressure tolerated by the surface without pinning occurring.

An optimum design procedure for both serial and parallel manipulators

Serial and parallel manipulators can be used in different manipulative tasks when their peculiarities in kinematic and dynamic behaviours are properly considered from the design stage. The basic performance in workspace, mobility constraints, and stiffness makes them alternative solutions and not competitive manipulator chains. Thus, it is convenient to deduce a common design procedure that considers common design criteria, but specific numerical evaluations. In this paper, a multi-objective optimization problem has been proposed to formulate a unique design procedure that takes into account the contradicting design optimality criteria in terms of suitable general algorithms for workspace volumes, Jacobian matrices, and compliant displacements. Numerical examples are reported to show not just the feasibility but also the numerical efficiency of the proposed formulations.

Fluid contact angle on solid surfaces: Role of multiscale surface roughness

We present a simple analytical model and an exact numerical study which explain the role of roughness on different length scales for the fluid contact angle on rough solid surfaces. We show that there is no simple relation between the distribution of surface slopes and the fluid contact angle. In particular, surfaces with the same distribution of slopes may exhibit very different contact angles depending on the range of length-scales over which the surfaces have roughness.

Statistical theory of wetting of liquid drops on superhydrophobic randomly rough surfaces

It is well known that hydrophobic surfaces may become superhydrophobic when their surface is properly roughened. However, the role of roughness is not yet very clear, notwithstanding several theoretical and experimental investigations. In the present paper, we propose a relatively simple theory aiming at calculating the apparent contact angle (ACA) and the contact area occurring in the case of drops gently deposited on two-dimensional randomly rough surfaces. Our theory applies both to isotropic and anisotropic rough surfaces, although in the latter case the predicted ACA has to be interpreted as the average contact angle at the triple line. We assume large separation of scales, i.e., that the spectral content of the surface lies in a range of wavelengths much smaller than the size of the apparent liquid-solid contact area. Results show that anisotropy negligibly affects the ACA, and a very reasonable agreement is obtained between theoretical ACA values and experimental data.

Experimental tests on operation performance of a LARM leg mechanism with 3-DOF parallel architecture

Abstract. In this paper, a prototype of a LARM leg mechanism is proposed by using a tripod manipulator and its operation performance is investigated through lab experimental tests. In particular, an experimental layout is presented for investigating operational performance. A prescribed motion with an isosceles trapezoid trajectory is used for characterizing the system behavior. Experiment results are analyzed for the purpose of operation evaluation and architecture design characterization of the tripod manipulator and its proposed prototype.

An effective medium approach to predict the apparent contact angle of drops on super-hydrophobic randomly rough surfaces

The apparent contact angle of large 2D drops with randomly rough self-affine profiles is numerically investigated. The numerical approach is based upon the assumption of large separation of length scales, i.e. it is assumed that the roughness length scales are much smaller than the drop size, thus making it possible to treat the problem through a mean-field like approach relying on the large-separation of scales. The apparent contact angle at equilibrium is calculated in all wetting regimes from full wetting (Wenzel state) to partial wetting (Cassie state). It was found that for very large values of the roughness Wenzel parameter (r(W) > -1/ cos θ(Y), where θ(Y) is the Young's contact angle), the interface approaches the perfect non-wetting condition and the apparent contact angle is almost equal to 180°. The results are compared with the case of roughness on one single scale (sinusoidal surface) and it is found that, given the same value of the Wenzel roughness parameter rW, the apparent contact angle is much larger for the case of a randomly rough surface, proving that the multi-scale character of randomly rough surfaces is a key factor to enhance superhydrophobicity. Moreover, it is shown that for millimetre-sized drops, the actual drop pressure at static equilibrium weakly affects the wetting regime, which instead seems to be dominated by the roughness parameter. For this reason a methodology to estimate the apparent contact angle is proposed, which relies only upon the micro-scale properties of the rough surface.

The sliding contact of a rigid wavy surface with a viscoelastic half-space

In this paper, the contact of a rigid sinusoid sliding on a viscoelastic half-space is studied. The solution of the problem is obtained by following the path drawn by Hunter for cylindrical contacts. Results show that depending on the remote applied load, a transition from full contact conditions to partial contact may occur depending on the sliding velocity. This effect, which is not observed in smooth single asperity contacts, is related to the viscoelastic stiffening of the material and to the periodicity of the contacts. Frictional properties as well as contact area, displacement and pressure distributions are discussed in detail.

Rough viscoelastic sliding contact: theory and experiments

In this paper, we show how the numerical theory introduced by the authors [Carbone and Putignano, J. Mech. Phys. Solids 61, 1822 (2013)] can be effectively employed to study the contact between viscoelastic rough solids. The huge numerical complexity is successfully faced up by employing the adaptive nonuniform mesh developed by the authors in Putignano et al. [J. Mech. Phys. Solids 60, 973 (2012)]. Results mark the importance of accounting for viscoelastic effects to correctly simulate the sliding rough contact. In detail, attention is, first, paid to evaluate the viscoelastic dissipation, i.e., the viscoelastic friction. Fixed the sliding speed and the normal load, friction is completely determined. Furthermore, since the methodology employed in the work allows to study contact between real materials, a comparison between experimental outcomes and numerical prediction in terms of viscoelastic friction is shown. The good agreement seems to validate-at least partially-the presented methodology. Finally, it is shown that viscoelasticity entails not only the dissipative effects previously outlined, but is also strictly related to the anisotropy of the contact solution. Indeed, a marked anisotropy is present in the contact region, which results stretched in the direction perpendicular to the sliding speed. In the paper, the anisotropy of the deformed surface and of the contact area is investigated and quantified.

Time-dependent relaxation of strained silicon-on-insulator lines using a partially coherent x-ray nanobeam

We report on the quantitative determination of the strain map in a strained silicon-on-insulator line with a 200×70 nm2 cross section. In order to study a single line as a function of time, we used an x-ray nanobeam with relaxed coherence properties as a compromise between beam size, coherence, and intensity. We demonstrate how it is possible to refine the line deformation map at the nanoscale, and follow its evolution as the line relaxes under the influence of the x-ray nanobeam. We find that the strained line flattens itself under irradiation but maintains the same linear strain (ε(zz) unchanged).

Thermal Ablation of Extended Liver Cancers: Assessment of Two New Bipolar Needle Electrodes

In the United States, approximately 155,000 new cases of cancer of the liver and bile duct occur annually. Surgical resection of these tumors is considered the only treatment modality with a curative effect, but only 10% to 15% of patients with liver tumors are considered candidates for surgical resection. For this reason, several alternative treatment modalities have been developed. Radiofrequency energy has been the focus of increasing research and practice over the past few years. Recently, needle electrodes that encompass larger tissue volumes and radiofrequency generators that provide the increased power levels needed to heat these larger tissue volumes have become available. For this pilot study, we were interested in the evaluation of the capacity of larger sized needle electrodes to induce a predictable zone of tissue necrosis within diseased human liver. Furthermore, we wanted to prove safety and effectiveness of radiofrequency ablation in large sized liver tumors. In summary, the use of a bipolar 6 or 8 array electrode and power up to 180–220 watts energy was shown to produce controlled coagulation necrosis of targeted liver parenchyma and tumor with no observed complications.

Association of obstructive sleep apnoea with the presence and severity of non-alcoholic fatty liver disease. A systematic review and meta-analysis

Obstructive sleep apnoea syndrome (OSAS) and non-alcoholic fatty liver disease (NAFLD) are common in clinical practice. NAFLD encompasses simple steatosis and non-alcoholic steatohepatitis (NASH): both confer an increased risk of cardiovascular disease and diabetes; NASH increases also liver-related risk. Growing experimental evidence connects chronic intermittent hypoxia of OSAS to NAFLD. We reviewed English and non-English articles and international meeting abstracts through December 2012. Observational studies were included if they assessed OSAS by polysomnography and NAFLD by histological, radiological or biochemical criteria. Two reviewers evaluated retrieved articles by appropriate quality scores. Main outcomes were pooled using random- or fixed-effects models. The effect of age, sex and body mass index (BMI) on effect estimates was assessed by meta-regression. Eighteen cross-sectional studies (2,183 participants) were included. Pooled odds ratios (ORs) of OSAS for the presence of NAFLD, as defined by histology, radiology, and AST or ALT elevation, were 2.01(95% CI: 1.36-2.97), 2.99(1.79-4.99), 2.36(1.46-3.82) and 2.60(1.88-3.61), respectively. Pooled ORs of OSAS for NASH, fibrosis-any stage, or advanced fibrosis in biopsy-proven NAFLD patients were 2.37(1.59-3.51), 2.16(1.45-3.20) and 2.30(1.21-4.38). The magnitude and direction of effects were unaffected by age, sex and BMI. In conclusion, OSAS is associated with an increased risk of NAFLD, NASH and fibrosis. OSAS patients should be screened for the presence and severity of NAFLD.

Role of statistical properties of randomly rough surfaces in controlling superhydrophobicity

We investigate the effect of statistical properties of the surface roughness on its superhydrophobicity. In particular, we focus on the liquid-solid interfacial structure and its dependence on the coupled effect of surface statistical properties and drop pressure. We find that, for self-affine fractal surfaces with Hurst exponent H > 0.5, the transition to the Wenzel state first involves the short wavelengths of the roughness and, then, gradually moves to larger and larger scales. However, as the drop pressure is increased, at a certain point of the loading history, an abrupt transition to the Wenzel state occurs. This sudden transition identifies the critical drop pressure p(W), which destabilizes the composite interface. We find that p(W) can be strongly enhanced by increasing the mean square slope of the surface, or equivalently the Wenzel roughness parameter r(W). Our investigation shows that, even in the case of randomly rough surface, r(W) is still the most crucial parameter in determining the superhydrophobicity of the surface. An analytical approach is, then, proposed to show that, for any given value of Young's contact angle θ(Y), a threshold value (r(W))(th) = 1/(-cos θ(Y)) exists, above which the composite interface is strongly stabilized and the surface presents robust superhydrophobic properties. Interestingly, this threshold value is identical to the one that would be obtained in pure Wenzel regime to guarantee perfect superhydrophobicity.

Analysis and design of a modular underactuated mechanism for robotic fingers

This paper presents an analysis of the design problems and requirements for underactuated mechanisms for robotic fingers. The case of performing a grasping task is considered and a solution is proposed that consists of a series of linked underactuated mechanisms. Optimality criteria are analysed with the aim of formulating a general design algorithm based on a suitable optimization problem. An example of a four-phalanx modular finger is used to highlight the practical feasibility of the proposed modular design concepts and procedures.

Microstructured superhydrorepellent surfaces: effect of drop pressure on fakir-state stability and apparent contact angles

In this paper we present a generalized Cassie-Baxter equation to take into account the effect of drop pressure on the apparent contact angle θ(app). Also we determine the limiting pressure p(W) which causes the impalement transition to the Wenzel state and the pull-off pressure p(out) at which the drop detaches from the substrate. The calculations have been carried out for axial-symmetric pillars of three different shapes: conical, hemispherical-topped and flat-topped cylindrical pillars. Calculations show that, assuming the same pillar spacing, conical pillars may be more inclined to undergo an impalement transition to the Wenzel state, but, on the other hand, they are characterized by a vanishing pull-off pressure which causes the drop not to adhere to the substrate and therefore to detach very easily. We infer that this property should strongly reduce the contact angle hysteresis as experimentally observed in Martines et al (2005 Nano Lett. 5 2097-103). It is possible to combine large resistance to impalement transition (i.e. large value of p(W)) and small (or even vanishing) detaching pressure p(out) by employing cylindrical pillars with conical tips. We also show that, depending on the particular pillar geometry, the effect of drop pressure on the apparent contact angle θ(app) may be more or less significant. In particular we show that in the case of conical pillars increasing the drop pressure causes a significant decrease of θ(app) in agreement with some experimental investigations (Lafuma and Quéré 2003 Nat. Mater. 2 457), whereas θ(app) slightly increases for hemispherical or flat-topped cylindrical pillars.

Workspace Analysis and Design Improvement of a Carotid Flow Measurement System

Heart and cerebrovascular diseases such as arteriosclerosis and myocardial ischemia dysfunction are currently among the main causes of death in developed countries. Recently, wave intensity (WI), which is an index used to obtain the force of cardiac contraction, has been investigated as a method for early-stage diagnosis of the above-mentioned diseases. Nevertheless, experimental tests have proven that the manual measurements of WI by means of commercial ultrasonic diagnostic systems require too much time and can be affected by the operator's skills. For this purpose, the introduction of robotic-assisted technology has advantages in terms of repetitiveness and accuracy of the measurement procedure. Therefore, at Waseda University, the development of a carotid blood flow measurement system has been proposed to support doctors while using ultrasound diagnostic equipment to measure the WI. This robotic system is composed of a serial robot with a wrist having a six-degree-of-freedom (6-DOF) parallel mechanism. The main focus is to obtain a suitable workspace performance of the 6-DOF parallel mechanism wrist. In this paper, a workspace analysis is carried out on a wrist prototype built for the Waseda-Tokyo Women's Medical Aloka Blood Flow Measurement System No.1 Refined (WTA-1R). Then, mechanical design enhancements are proposed and validated to provide a suitable workspace performance both as reachable workspace and dexterity, and a refined prototype WTA-1RII has been built.

Three-dimensional x-ray Fourier transform holography: the Bragg case

A novel approach to determine the structure of nanoscale crystals in three dimensions is proposed by the use of coherent x-ray Fourier transform holography in Bragg geometry. The full internal description is directly obtained by a single Fourier transform of the 3D intensity hologram. Together with the morphology, Bragg geometry gives access to the 3D displacement field within the crystal. This result opens great possibilities for the investigation of strain fields inside nanocrystals in a simple way.

Experimental and Numerical Characterization of CaPaMan 2bis Operation

In this paper, the operation performance of CaPaMan 2bis (Cassino Parallel Manipulator 2 bis) was investigated through lab experimental tests and computer simulations. Milli‐CaTraSys (Milli‐Cassino Tracking System) was implemented to determine displacements and orientation variations of CaPaMan 2bis end‐effector during experimental tests. A 3D (three dimension) virtual model was built in ADAMS environment to simulate the operation behavior for different prescribed motions. Several prescribed motions have been simulated and tested under different conditions in order to characterize the system behavior. In particular, the kinematic characteristics were obtained from both, experimental tests and numerical simulations. Finally, experiment results and simulation computations were compared for purpose of performance evaluation and design characterization of the parallel manipulator structure and its prototype.

Liquid crystal director dynamics imaged using two-photon fluorescence microscopy with remote focusing

We introduce a novel imaging technique adopting remote focusing for resolving the axial dynamics in the director field for liquid crystals. The high axial time resolution of our approach is demonstrated by imaging directly the evolution of the director field for an initially splayed nematic layer subject to a sudden voltage pulse. Images of the switching dynamics are presented, revealing transient state director configurations and changes in topology of the liquid crystal layer.

Adhesive contact of rough surfaces: comparison between numerical calculations and analytical theories

The authors have employed a numerical procedure to analyse the adhesive contact between a soft elastic layer and a rough rigid substrate. The solution to the problem, which belongs to the class of the free boundary problems, is obtained by calculating Green's function which links the pressure distribution to the normal displacements at the interface. The problem is then formulated in the form of a Fredholm integral equation of the first kind with a logarithmic kernel. The boundaries of the contact area are calculated by requiring the energy of the system to be stationary. This methodology has been employed to study the adhesive contact between an elastic semi-infinite solid and a randomly rough rigid profile with a self-affine fractal geometry. We show that, even in the presence of adhesion, the true contact area still linearly depends on the applied load. The numerical results are then critically compared with the predictions of an extended version of Persson's contact mechanics theory, which is able to handle anisotropic surfaces, as 1D interfaces. It is shown that, for any given load, Persson's theory underestimates the contact area by about 50% in comparison with our numerical calculations. We find that this discrepancy is larger than for 2D rough surfaces in the case of adhesionless contact. We argue that this increased difference might be explained, at least partially, by considering that Persson's theory is a mean-field theory in spirit, so it should work better for 2D rough surfaces rather than for 1D rough surfaces. We also observe that the predicted value of separation is in agreement with our numerical results as well as the exponents of the power spectral density of the contact pressure distribution and of the elastic displacement of the solid. Therefore, we conclude that Persson's theory captures almost exactly the main qualitative behaviour of the rough contact phenomena.

The neural cell adhesion molecule (NCAM) present in the cerebrospinal fluid of multiple sclerosis patients is unsialylated

The neural cell adhesion molecule (NCAM) is a glycoprotein localised in the plasma membrane of neural and glial cells, which plays a role in myelination and remyelination. It increases in the cerebrospinal fluid (CSF) of acute multiple sclerosis (MS) patients treated with corticosteroids who are improving after an attack, but it has not been shown if it appears in its sialylated (PSA) or unsialylated form. We studied the NCAM and the PSA-NCAM in serum and CSF samples of 16 acute and non-acute MS patients and in the sera of 10 non-neurological controls. The NCAM and the PSA-NCAM were dosed by two different ELISA previously set-up. The NCAM in the serum and in the CSF of the control group presented mean levels similar to those shown in previous papers: 1620 +/- 216 and 970 +/- 210 ng/ml. In the MS patient group the means were 1700 +/- 546 in the sera and 926 +/- 285 in the CSFs. All the sera were PSA-NCAM-positive: the mean PSA-NCAM concentration in the control group was 3150 +/- 950 ng/ml, while in the MS patient group it was 3570 +/- 905 ng/ml. The correlation between serum levels of NCAM and PSA-NCAM was highly significant (p < 0.001). Student's "t" test did not show any significant difference between serum levels of the two groups, both for the NCAM and for the PSA-NCAM. CSF samples did not show any positive results for the PSA-NCAM, in either controls or in MS patients. These results demonstrate that the high levels of NCAM we previously found in the CSF of improving MS patients treated with steroids did not contain a quota of PSA-NCAM, but only the unsialylated soluble form of the molecule.

Contact mechanics and rubber friction for randomly rough surfaces with anisotropic statistical properties

In this paper we extend the theory of contact mechanics and rubber friction developed by one of us (B.N.J. Persson, J. Chem. Phys. 115, 3840 (2001)) to the case of surfaces with anisotropic surface roughness. As an application we calculate the viscoelastic contribution to the rubber friction. We show that the friction coefficient may depend significantly on the sliding direction, while the area of contact depends weakly on the sliding direction. We have carried out experiments for rubber blocks sliding on unidirectionally polished steel surfaces. The experimental data are in a good qualitative agreement with the theory.

Quality in emergency departments: a study on 3,285,440 admissions

INTRODUCTION

A multi-centre study has been conducted, during 2005, by means of a questionnaire posted on the Italian Society of Emergency Medicine (SIMEU) web page. Our intention was to carry out an organisational and functional analysis of Italian Emergency Departments (ED) in order to pick out some macro-indicators of the activities performed. Participation was good, in that 69 ED (3,285,440 admissions to emergency services) responded to the questionnaire.

METHODS

The study was based on 18 questions: 3 regarding the personnel of the ED, 2 regarding organisational and functional aspects, 5 on the activity of the ED, 7 on triage and 1 on the assessment of the quality perceived by the users of the ED.

RESULTS AND CONCLUSION

The replies revealed that 91.30% of the ED were equipped with data-processing software, which, in 96.83% of cases, tracked the entire itinerary of the patient. About 48,000 patients/year used the ED: 76.72% were discharged and 18.31% were hospitalised. Observation Units were active in 81.16% of the ED examined. Triage programmes were in place in 92.75% of ED: in 75.81% of these, triage was performed throughout the entire itinerary of the patient; in 16.13% it was performed only symptom-based, and in 8.06% only on-call. Of the patients arriving at the ED, 24.19% were assigned a non-urgent triage code, 60.01% a urgent code, 14.30% a emergent code and 1.49% a life-threatening code. Waiting times were: 52.39 min for non-urgent patients, 40.26 min for urgent, 12.08 for emergent, and 1.19 for life-threatening patients.

Primary lumbar hernia repair: the open approach

BACKGROUND

Lumbar hernias arise through posterolateral abdominal wall defects, named inferior triangle (Petit) and superior triangle (Grynfelt). Most of the lumbar hernias are secondary to trauma or previous surgery, while primary lumbar hernias are rare. There are two possible surgical approaches: the anterior approach with lumbar incision and the laparoscopic (transabdominal or totally extraperitoneal) approach.

METHODS

We present a series of nine surgical procedures for primary lumbar hernia in 7 adult patients (2 affected by bilateral hernias). Seven were Grynfelt hernias, and two were Petit hernias. All surgical repairs were performed using synthetic mesh placed in the extraperitoneal space, below the muscular layers, using a tension-free technique.

RESULTS

There was no surgical complication, except for 1 case with a subcutaneous haematoma. The mean hospital stay was 2.3 days. All patients returned to normal daily activities within 15 days after surgery. After a median follow-up period of 25 months, there was no case of recurrence or postsurgical sequelae, such as pain or muscular weakness.

CONCLUSIONS

Primary lumbar hernias are rare congenital defects of the abdominal wall. Repair of these rare hernias can be successfully performed via the anterior approach with the use of synthetic mesh - this method of repair is easy, safe, and effective.

Workspace analysis and performance of a binary actuated parallel manipulator with flexural joints

In this paper the design of a miniaturized parallel architecture is investigated in terms of basic performances concerning mobility and workspace characteristics. The miniature requirements have been achieved with a milli-scaled parallel manipulator requiring flexural joints and binary actuation with shape memory alloy wires or small pneumatic pistons. The mechanical design is analysed by considering the mobility of the flexural joints in order to size them and model the kinematics of the joints. The reachability is analysed through a suitable formulation of the direct kinematics by also taking into account binary actuation. Workspace performance has been determined in terms of position and orientation capabilities.

Numerical and experimental analyses of radial cams with circular-arc profiles

Cam profiles with circular arcs can be useful for low-cost transmissions and for applications in micromachines. They are usually designed by means of graphical techniques. Recently, at Laboratory of Robotics and Mechatronics (LARM) in Cassino, a research line addressed the problems of modern design and characterization of cams with circular-arc profiles by looking at computer-oriented formulations and by investigating experimentally the operation characteristics. In this article, we have given an overview of the results achieved for radial cams and also attempted to extend to a general case that is useful for studying and validating any planar cam profile. The approach is algebraic, because it is based on the geometry of the mechanical design of circular-arc profiles. The experimental analysis has been conceived for a low-cost easy-operation performance of the circular-arc profiles, using a suitable test-bed that has been designed at LARM in Cassino. The results of the experimental tests are useful to validate both the numerical design procedure and the designed cam profiles. Examples are reported to illustrate the practical engineering feasibility of the proposed analysis procedures for radial cams with circular-arc profiles.

Hot cracks in rubber: origin of the giant toughness of rubberlike materials

We study crack propagation in rubberlike materials and show that the nonuniform temperature distribution which occurs in the vicinity of the crack tip has a profound influence on the crack propagation, and may strongly enhance the crack propagation energy G(v) for high crack velocities v. At very low crack-tip velocities, the heat produced at the crack tip can diffuse away, but already at moderate crack-tip velocities a very large temperature increase occurs close to the crack tip resulting in a "hot-crack" propagation regime. The transition between the low-speed regime and the hot-crack regime is very abrupt and may result in unstable crack motion, e.g., stick-slip motion or catastrophic failure.

Crack motion in viscoelastic solids: the role of the flash temperature

We present a simple theory of crack propagation in viscoelastic solids. We calculate the energy per unit area, G(v), to propagate a crack, as a function of the crack tip velocity v. Our study includes the non-uniform temperature distribution (flash temperature) in the vicinity of the crack tip, which has a profound influence on G(v). At very low crack tip velocities, the heat produced at the crack tip can diffuse away, resulting in very small temperature increase: in this "low-speed" regime the flash temperature effect is unimportant. However, because of the low heat conductivity of rubber-like materials, already at moderate crack tip velocities a very large temperature increase (of order of 1000 K) can occur close to the crack tip. We show that this will drastically affect the viscoelastic energy dissipation close to the crack tip, resulting in a "hot-crack" propagation regime. The transition between the low-speed regime and the hot-crack regime is very abrupt, which may result in unstable crack motion, e.g. stick-slip motion or catastrophic failure, as observed in some experiments. In addition, the high crack tip temperature may result in significant thermal decomposition within the heated region, resulting in a liquid-like region in the vicinity of the crack tip. This may explain the change in surface morphology (from rough to smooth surfaces) which is observed as the crack tip velocity is increased above the instability threshold.

Atomic force microscope study of presmectic modulation in the nematic and isotropic phases of the liquid crystal octylcyanobiphenyl using piezoresistive force detection

Using a temperature controlled atomic force microscope (AFM), we have studied surface induced pre-smectic order in the nematic and isotropic phases of 4-cyano- 4'-n -octylbiphenyl. A modified AFM head with piezoresitive cantilevers has been used to measure the structural force between a flat BK7 glass plate and a 10 microm glass sphere, both being treated to induce homeotropic alignment of the confined liquid crystal layer in between. We have observed surface-induced presmectic force not only in the isotropic, but also in the nematic phase. We have measured the temperature dependencies of the presmectic force, the smectic correlation length xi and the smectic order parameter psi at the surface. The correlation length xi(T) shows a power-law temperature dependence with a critical exponent of nu=0.67 +/- 0.03 and the bare correlation length of xi(0) = (0.39 +/- 0.08) nm, in good agreement with x-ray data. The smectic density at the surface is psi(2)(S) =0.4 in the nematic phase and decreases in the isotropic phase.

Hydrophobic properties of a wavy rough substrate

The wetting/non-wetting properties of a liquid drop in contact with a chemically hydrophobic rough surface (thermodynamic contact angle theta(e)>pi/2) are studied for the case of an extremely idealized rough profile: the liquid drop is considered to lie on a simple sinusoidal profile. Depending on surface geometry and pressure values, it is found that the Cassie and Wenzel states can coexist. But if the amplitude h of the substrate is sufficiently large the only possible stable state is the Cassie one, whereas if h is below a certain critical value hcr a transition to the Wenzel state occurs. Since in many potential applications of such super-hydrophobic surfaces, liquid drops often collide with the substrate (e.g. vehicle windscreens), in the paper the critical drop pressure pW is calculated at which the Cassie state is no longer stable and the liquid jumps into full contact with the substrate (Wenzel state). By analyzing the asymptotic behavior of the systems in the limiting case of a large substrate corrugation, a simple criterion is also proposed to calculate the minimum height asperity h necessary to prevent the Wenzel state from being formed, to preserve the super-hydrophobic properties of the substrate, and, hence, to design a robust super-hydrophobic surface.

Is it possible to reduce job burnout of the health care staff working with demented patients?

The Maslach burnout inventory (MBI) was administered to the health care staff of a nursing home before implementing a therapeutic program of occupational therapy and cognitive rehabilitation for demented patients and one year later, while the patients continued the rehabilitative and occupational therapy. All the indices of the MBI showed a significant improvement at the staff's evaluation, when was appraised 12 months after the beginning of the therapeutic program. These treatments seem to have positive effects on both the patients, improving their performances, and the nursing staff, as an aid to reduce the job burnout.

Dewetting at soft viscoelastic interfaces

The dewetting transition of thin liquid films (approximately 100 nm) at soft viscoelastic interfaces is analyzed theoretically. It is shown that viscoelastic losses in the soft material can drastically increase the time to complete the dewetting. Thus, the influence of the thinning of the liquid film, due to the hydrodynamic drainage caused by the external applied pressure, has to be considered too. The squeezing pressure coupled with the hydrodynamic drainage may slow down the dewetting to almost zero growth rate of the dry zone; in this case a trapped rim of fluid should be observed.

Acute respiratory failure in patients with severe community-acquired pneumonia. A prospective randomized evaluation of noninvasive ventilation

In uncontrolled studies, noninvasive positive pressure ventilation (NPPV) was found useful in avoiding endotracheal intubation in patients with acute respiratory failure (ARF) caused by severe community-acquired pneumonia (CAP). We conducted a prospective, randomized study comparing standard treatment plus NPPV delivered through a face mask to standard treatment alone in patients with severe CAP and ARF. Patients fitting the American Thoracic Society criteria for severe CAP were included in presence of ARF (refractory hypoxemia and/or hypercapnia with acidosis). Exclusion criteria were: severe hemodynamic instability, requirement for emergent cardiopulmonary resuscitation, home mechanical ventilation or oxygen long-term supplementation, concomitant severe disease with a low expectation of life, inability to expectorate or contraindications to the use of the mask. Fifty-six consecutive patients (28 in each arm) were enrolled, and the two groups were similar at study entry. The use of NPPV was well tolerated, safe, and associated with a significant reduction in respiratory rate, need for endotracheal intubation (21% versus 50%; p = 0.03), and duration of intensive care unit (ICU) stay (1.8 +/- 0.7 d versus 6 +/- 1.8 d; p = 0.04). The two groups had a similar intensity of nursing care workload, time interval from study entry to endotracheal intubation, duration of hospitalization, and hospital mortality. Among patients with chronic obstructive pulmonary disease (COPD), those randomized to NPPV had a lower intensity of nursing care workload (p = 0.04) and improved 2-mo survival (88.9% versus 37.5%; p = 0.05). We conclude that in selected patients with ARF caused by severe CAP, NPPV was associated with a significant reduction in the rate of endotracheal intubation and duration of ICU stay. A 2-mo survival advantage was seen in patients with COPD.

[Renal oncocytoma: its differential diagnosis and the indications for surgical treatment]

The authors report an uncommon renal oncocytoma rate stressing difficulties that modern diagnostic modalities meet in a correct preoperative differential diagnosis with nephrocarcinoma. Oncocytoma is a low multifocal involvement. Surgical treatment is the primary choice, nephrectomy about localized monofocal lesions in advisable, with short and long term positive outcomes. In ambilateral involvement case without malignancy evident signs (scarce likelihood to infiltrate nephritic capsule, without lymphoadenopathy) conservative operations with partial resections are suggested with a five years survival from 84 to 96%.

[A rare case of gastric bleeding due to left-sided portal hypertension]

The authors report an uncommon gastric bleeding rate due to splenic hilum compression by a pancreatic cyst. The syndrome to be brought back to some sectorial portal hypertension form (left-sided portal hypertension) is difficult to diagnose because of absence of esophageal varices and other portal hypertension signs in an unchanged liver functionality patient. To put a correct diagnosis about gastric bottom bleeding varices without hepatic origin, the authors recommend to use arteriography and CT. Surgical treatment is proved to be the election one because of useless attempt of bleeding control through hepatic artery endoscopic sclerosis or embolization.

Suicide in two patients with a diagnosis of probable Alzheimer disease

Two patients meeting the criteria for probable Alzheimer disease (AD) who were participating in a phase 3 clinical program with eptastigmine, a cholinesterase inhibitor, committed suicide. The first patient committed suicide by a self-inflicted gunshot wound to the head. The second patient committed suicide by jumping from a 19th story window. These two patients shared several clinical features with those found in the literature: being at the early stages of the disease, having a high level education, with preserved insight, having access to firearms, and being aware of not responding to pharmacological treatment.