Fluorescent labelled thiourea-bridged glycodendrons

GlcNAc-coated glycodendrimers, which are polyvalent glycomimetics, display strong in vitro affinity for the rat natural killer cell protein-1A (NKR-P1A), a C-type lectin-like receptor of natural killer (NK) cells in rats, humans and some strains of mice. Administration of these compounds in vivo results in a substantial increase in the antitumour activity with involvement of the natural cell immunity. To clarify the in vitro and in vivo fate of these molecules, we synthesized labelled glycodendron analogues of the previously studied glycodendrimers. Labelling with fluorescent tags enabled the localization of the glycodendrons in white blood cells, tumours and other tissues by using different imaging techniques such as fluorescence and confocal microscopy. These studies are useful for probing the mechanism of action and fate of artificial ligands and the cell receptors involved.     

An asymptotic-numerical method to compute bifurcating branches

In this paper a new method to compute the bifurcating branches for an elastic structure is presented. The method is based on the asymptotic-numerical method (ANM), that is a perturbation technique to solve problems in non-linear mechanics. Herein, we present a computing strategy to find the bifurcation points and the post-buckling branches in the framework of the ANM. Some examples are also given, which prove the effectiveness of the proposed method. A discussion of the results and of the open problems ends the paper. © 1998 John Wiley & Sons, Ltd.     

Kynurenine/Tryptophan Ratio as a Potential Blood-Based Biomarker in Non-Small Cell Lung Cancer

The enzyme indoleamine 2,3-dioxygenase 1 (IDO1) degrade tryptophan (Trp) into kynurenine (Kyn) at the initial step of an enzymatic pathway affecting T cell proliferation. IDO1 is highly expressed in various cancer types and associated with poor prognosis. Nevertheless, the serum Kyn/Trp concentration ratio has been suggested as a marker of cancer-associated immune suppression. We measured Kyn and Trp in blood samples of a wide cohort of non-small-cell lung cancer (NSCLC) patients, before they underwent surgery, and analyzed possible correlations of the Kyn/Trp ratio with either IDO1 expression or clinical–pathological parameters. Low Kyn/Trp significantly correlated with low IDO1 expression and never-smoker patients; while high Kyn/Trp was significantly associated with older (≥68 years) patients, advanced tumor stage, and squamous cell carcinoma (Sqcc), rather than the adenocarcinoma (Adc) histotype. Moreover, high Kyn/Trp was associated, among the Adc group, with higher tumor stages (II and III), and, among the Sqcc group, with a high density of tumor-infiltrating lymphocytes. A trend correlating the high Kyn/Trp ratio with the probability of recurrences from NSCLC was also found. In conclusion, high serum Kyn/Trp ratio, associated with clinical and histopathological parameters, may serve as a serum biomarker to optimize risk stratification and therapy of NSCLC patients.     

A Bayesian hierarchical model for maximizing the vascular adhesion of nanoparticles

The complex vascular dynamics and wall deposition of systemically injected nanoparticles is regulated by their geometrical properties (size, shape) and biophysical parameters (ligand–receptor bond type and surface density, local shear rates). Although sophisticated computational models have been developed to capture the vascular behavior of nanoparticles, it is increasingly recognized that purely deterministic approaches, where the governing parameters are known a priori and conclusively describe behaviors based on physical characteristics, may be too restrictive to accurately reflect natural processes. Here, a novel computational framework is proposed by coupling the physics dictating the vascular adhesion of nanoparticles with a stochastic model. In particular, two governing parameters (i.e. the ligand–receptor bond length and the ligand surface density on the nanoparticle) are treated as two stochastic quantities, whose values are not fixed a priori but would rather range in defined intervals with a certain probability. This approach is used to predict the deposition of spherical nanoparticles with different radii, ranging from 750 to 6,000 nm, in a parallel plate flow chamber under different flow conditions, with a shear rate ranging from 50 to 90  $\text {s}^{-1}$ . It is demonstrated that the resulting stochastic model can predict the experimental data more accurately than the original deterministic model. This approach allows one to increase the predictive power of mathematical models of any natural process by accounting for the experimental and intrinsic biological uncertainties.     

Noncoherent detection of coherent lightwave signals corrupted byphase noise

Waves are treated that modulate by either on-off keying (OOK) or binary frequency-shift keying (FSK) and are further impaired by additive Gaussian noise. Heterodyne detection of such a waveform produces an electronic bandpass signal, which, to ease demodulation in the presence of phase noise, is noncoherently demodulated to extract the baseband pulse stream. The treatment goes beyond previous bit error rate (BER) analyses of optical heterodyne receivers for OOK and FSK. First, there is full adherence to the standard (Brownian motion) model of phase noise. Also, the receiver structure is formulated in such a way that the probability density function of the receiver output samples can be accurately determined. This permits calculations of the additive noise and phase noise tolerable when achieving bit error rates as small as 10 ^-9. Finally, the study is comprehensive regarding the range of parameters explored. Filtering at an intermediate frequency (IF) alone, as well as IF filtering plus postdetection low-pass filtering, is considered. When the receiver parameters decision threshold (for OOK) and IF filter bandwidth are optimized, large amounts of phase noise can be accommodated with only minor increases in required signal-to-noise ratio. This is especially important when the bit rate is moderate compared to the laser linewidth     

Experimental spreading and despreading of the optical spectrum

An experimental realization of direct-sequence spreading and despreading of the optical spectrum using off-the-shelf electrooptic modulators is reported. This capability is required to implement a fiber-optic network originally devised by G. Foschini and G. Vannucci (1983). The network utilizes spread-spectrum techniques on the optical spectrum, together with coherent signal detection to accommodate a very large number of simultaneous users, for a total throughput measured in hundreds of Gb/s. The results obtained provide confidence that a network built around this idea would perform according to theoretical calculations. Coherent spectral spreading and despreading is thus established as a promising communication technique for fiber-optic systems     

Relationship between wear of friction materials and dissipated power density

Specific tribometric tests showed both the effect and relevance of the power dissipated by friction upon the transition from mild wear to severe wear for friction materials. The dissipated power density could be viewed as an important variable either to identify the critical wear characteristics of friction materials or to make comparisons among different types of friction materials. The scanning electron microscopy analysis showed some correspondence between the sliding surface morphology after the friction tests and the wear rate obtained. Moreover, the phenomena observed are related to known mechanochemical wear mechanisms.     

Combining frequency-division and code-division multiplexing in ahigh-capacity optical network

The combination of frequency division and code division multiplexing in a multiaccess network such that the beneficial aspects of each technique mitigate the shortcomings of the other is addressed. The feasibility and expected performance of the resulting hybrid network are examined. CDMA (code-division multiple access) is used to eliminate the need for laser frequency control, which is required for pure FDMA (frequency-division multiaccess) schemes. On the other hand, an FDMA-like mutual avoidance scheme exploits the limited tunability available to keep signals away from one another as much as possible, relieving the need for CDMA to protect against more than the occasional crossover of one interfering signal. This significantly limits the amount of spectral spreading required. The use of the hybrid network for high-bit-rate and low-bit-rate applications is discussed. The power budget for a local network utilizing a star coupler is outlined     

Evanescent-mode applicators (EMA) for superficial and subcutaneoushyperthermia

Evanescent-mode waveguide aperture applicators are proposed for hyperthermic treatments of superficial and subcutaneous tissues. They consist of air-filled waveguide segments that work below the cutoff frequency and therefore support only evanescent transverse modes. These are excited by radiators of suitable symmetry and configuration to produce modal heating fields of selected cross-sections. This field emerges from the waveguide active aperture and enters the tissue to be heated through an air gap. These devices work in a very large range of frequencies and are extremely simple to manufacture, even with a variety of cross-section sizes and shapes, because of their air-filled feature. This enables good heating field flexibility with improved penetration to be obtained. Their operation is safe and practical also on irregular and curved tissue surfaces     

27 MHz conformal capacitive ring (CR) applicators for uniformhyperthermic/diathermic treatment of body segments with axialfields

A family of 27 MHz heating devices has been developed and fundamental tests carried out. The devices consist in a pair of ring-like, flexible, capacitive electrodes, conformally wrapped round the tissue to be heated, for use in hyperthermia and rehabilitation treatment. These capacitive ring (CR) applicators produce an axial E-field which can uniformly heat the central portion of a 20 cm OD cylindrical phantom simulating fat and muscle tissues. This electrode-body configuration can be used to uniformly heat most human body segments with the highest symmetry congruence, the RF currents flowing parallel to the boundaries provided by the pseudo-axial symmetry of these segments. With respect to the rigid pads used in RF capacitive heating, the CR electrodes exhibit a larger working surface area. Moreover, they may be used with an interposed dielectric layer between the electrodes and the skin, to reduce edge effects. With respect to the axially symmetric radiators of higher frequency, they are applicable to larger cross-section body segments with increased penetration and without the need of an integral water bolus. The CR devices allow free access to most of the body surface for skin temperature measurement and conditioning, and for combined treatments. Moreover, the almost uniform heating pattern may represent a useful feature for standardizing treatment. The CR electrodes can easily be matched to the RF source even if they are low impedance devices, and they give rise to low-level stray fields, which can be taken care of by a local shield. These CR devices can be considered safe and practical and suitable for regional hyperthermic and rehabilitation treatment.