Harmonic analysis and reduction of the scattered field from electrically large cloaked metallic cylinders

In this paper, an analysis of the spectral composition of the scattered field from coated metallic cylinders is performed, focusing particularly on the cloaking of electrically large structures. An expression of the scattering coefficients is derived, considering both a dielectric and a metasurface coating. Modeling the metasurface as a surface impedance boundary condition, the surface impedance, which annuls one harmonic of the scattered field, is formulated in a closed and compact form. Moreover, in the case of cylinders with radius comparable with the wavelength of interest, it is demonstrated that a reduction of the scattering is possible by using a homogeneous metasurface coating, which presents a positive surface reactance. In particular, a reduction of the scattering width of 4 dB is achieved for a cylinder radius of a = 0.917λ0

Myelin pathology: Involvement of molecular chaperones and the promise of chaperonotherapy

The process of axon myelination involves various proteins including molecular chaperones. Myelin alteration is a common feature in neurological diseases due to structural and functional abnormalities of one or more myelin proteins. Genetic proteinopathies may occur either in the presence of a normal chaperoning system, which is unable to assist the defective myelin protein in its folding and migration, or due to mutations in chaperone genes, leading to functional defects in assisting myelin maturation/migration. The latter are a subgroup of genetic chaperonopathies causing demyelination. In this brief review, we describe some paradigmatic examples pertaining to the chaperonins Hsp60 (HSPD1, or HSP60, or Cpn60) and CCT (chaperonin-containing TCP-1). Our aim is to make scientists and physicians aware of the possibility and advantages of classifying patients depending on the presence or absence of a chaperonopathy. In turn, this subclassification will allow the development of novel therapeutic strategies (chaperonotherapy) by using molecular chaperones as agents or targets for treatment

Testing silicone digit extensions as a way to suppress natural sensation to evaluate supplementary tactile feedback

Dexterous use of the hands depends critically on sensory feedback, so it is generally agreed that functional supplementary feedback would greatly improve the use of hand prostheses. Much research still focuses on improving non-invasive feedback that could potentially become available to all prosthesis users. However, few studies on supplementary tactile feedback for hand prostheses demonstrated a functional benefit. We suggest that confounding factors impede accurate assessment of feedback, e.g., testing non-amputee participants that inevitably focus intently on learning EMG control, the EMG’s susceptibility to noise and delays, and the limited dexterity of hand prostheses. In an attempt to assess the effect of feedback free from these constraints, we used silicone digit extensions to suppress natural tactile feedback from the fingertips and thus used the tactile feedback-deprived human hand as an approximation of an ideal feed-forward tool. Our non-amputee participants wore the extensions and performed a simple pick-and-lift task with known weight, followed by a more difficult pick-and-lift task with changing weight. They then repeated these tasks with one of three kinds of audio feedback. The tests were repeated over three days. We also conducted a similar experiment on a person with severe sensory neuropathy to test the feedback without the extensions. Furthermore, we used a questionnaire based on the NASA Task Load Index to gauge the subjective experience. Unexpectedly, we did not find any meaningful differences between the feedback groups, neither in the objective nor the subjective measurements. It is possible that the digit extensions did not fully suppress sensation, but since the participant with impaired sensation also did not improve with the supplementary feedback, we conclude that the feedback failed to provide relevant grasping information in our experiments. The study highlights the complex interaction between task, feedback variable, feedback delivery, and control, which seemingly rendered even rich, high-bandwidth acoustic feedback redundant, despite substantial sensory impairment

Testing silicone digit extensions as a way to suppress natural sensation to evaluate supplementary tactile feedback

Dexterous use of the hands depends critically on sensory feedback, so it is generally agreed that functional supplementary feedback would greatly improve the use of hand prostheses. Much research still focuses on improving non-invasive feedback that could potentially become available to all prosthesis users. However, few studies on supplementary tactile feedback for hand prostheses demonstrated a functional benefit. We suggest that confounding factors impede accurate assessment of feedback, e.g., testing non-amputee participants that inevitably focus intently on learning EMG control, the EMG's susceptibility to noise and delays, and the limited dexterity of hand prostheses. In an attempt to assess the effect of feedback free from these constraints, we used silicone digit extensions to suppress natural tactile feedback from the fingertips and thus used the tactile feedback-deprived human hand as an approximation of an ideal feed-forward tool. Our non-amputee participants wore the extensions and performed a simple pick-and-lift task with known weight, followed by a more difficult pick-and-lift task with changing weight. They then repeated these tasks with one of three kinds of audio feedback. The tests were repeated over three days. We also conducted a similar experiment on a person with severe sensory neuropathy to test the feedback without the extensions. Furthermore, we used a questionnaire based on the NASA Task Load Index to gauge the subjective experience. Unexpectedly, we did not find any meaningful differences between the feedback groups, neither in the objective nor the subjective measurements. It is possible that the digit extensions did not fully suppress sensation, but since the participant with impaired sensation also did not improve with the supplementary feedback, we conclude that the feedback failed to provide relevant grasping information in our experiments. The study highlights the complex interaction between task, feedback variable, feedback delivery, and control, which seemingly rendered even rich, high-bandwidth acoustic feedback redundant, despite substantial sensory impairment

5-(carbamoylmethylene)-oxazolidin-2-ones as a promising class of heterocycles inducing apoptosis triggered by increased ROS levels and mitochondrial dysfunction in breast and cervical cancer

Oxazolidinones are antibiotics that inhibit protein synthesis by binding the 50S ribosomal subunit. Recently, numerous worldwide researches focused on their properties and possible involvement in cancer therapy have been conducted. Here, we evaluated in vitro the antiproliferative activity of some 5-(carbamoylmethylene)-oxazolidin-2-ones on MCF-7 and HeLa cells. The tested compounds displayed a wide range of cytotoxicity on these cancer cell lines, measured by MTT assay, exhibiting no cytotoxicity on non-tumorigenic MCF-10A cells. Among the nine tested derivatives, four displayed a good anticancer potential. Remarkably, OI compound showed IC50 values of 17.66 and 31.10 µM for MCF-7 and HeLa cancer cells, respectively. Furthermore, we assessed OI effect on the cell cycle by FACS analysis, highlighting a G1 phase arrest after 72 h, supported by a low expression level of Cyclin D1 protein. Moreover, mitochondrial membrane potential was reduced after OI treatment driven by high levels of ROS. These findings demonstrate that OI treatment can inhibit MCF-7 and HeLa cell proliferation and induce apoptosis by caspase-9 activation and cytochrome c release in the cytosol. Hence, 5-(carbamoylmethylene)-oxazolidin-2-ones have a promising anticancer activity, in particular, OI derivative could represent a good candidate for in vivo further studies and potential clinical use

Robot-aided assessment of wrist proprioception

Introduction: Impaired proprioception severely affects the control of gross and fine motor function. However, clinical assessment of proprioceptive deficits and its impact on motor function has been difficult to elucidate. Recent advances in haptic robotic interfaces designed for sensorimotor rehabilitation enabled the use of such devices for the assessment of proprioceptive function. Purpose: This study evaluated the feasibility of a wrist robot system to determine proprioceptive discrimination thresholds for two different DoFs of the wrist. Specifically, we sought to accomplish three aims: first, to establish data validity; second, to show that the system is sensitive to detect small differences in acuity; third, to establish test–retest reliability over repeated testing. Methodology: Eleven healthy adult subjects experienced two passive wrist movements and had to verbally indicate which movement had the larger amplitude. Based on a subject’s response data, a psychometric function was fitted and the wrist acuity threshold was established at the 75% correct response level. A subset of five subjects repeated the experimentation three times (T1, T2, and T3) to determine the test–retest reliability. Results: Mean threshold for wrist flexion was 2.15° ± 0.43° and 1.52° ± 0.36° for abduction. Encoder resolutions were 0.0075° (flexion–extension) and 0.0032° (abduction–adduction). Motor resolutions were 0.2°(flexion–extension) and 0.3° (abduction–adduction). Reliability coefficients were rT2-T1 = 0.986 and rT3-T2 = 0.971. Conclusion: We currently lack established norm data on the proprioceptive acuity of the wrist to establish direct validity. However, the magnitude of our reported thresholds is physiological, plausible, and well in line with available threshold data obtained at the elbow joint. Moreover, system has high resolution and is sensitive enough to detect small differences in acuity. Finally, the system produces reliable data over repeated testing

CFD-based scale-up of hydrodynamics and mixing in bubble columns

Unsteady and three-dimensional Eulerian–Eulerian CFD simulations of bubble column reactors under operating conditions of industrial interest are discussed in this work. The flow pattern in this equipment depends strongly on the interactions between the gas and liquid phases, mainly via the drag force. In this work, a correlation for the drag force coefficient is tested and improved to consider the so-called swarm effect that modifies the drag force at high gas volume fractions. The improved swarm factor proposed in this work is the adjustment of the swarm factor proposed by Simonnet et al. (2008). This new swarm factor is suitable for very high gas volume fractions without generating stability problems, which were encountered with the original formulation. It delivers an accurate prediction of gas volume fraction and liquid velocity in a wide range of tested operating conditions. Results are validated by comparison with experimental data on bubble column reactors at different scales and for several operating conditions. Hydrodynamics is well predicted for every operating condition at different scales. Several turbulence models are tested. Finally, the contribution of Bubble Induced Turbulence (BIT), as proposed by Alméras et al. (2015), on mixing is evaluated via an analysis of the mixing time

Ideal Magnetic Dipole: Scattering and Mantle Cloaking Effects

Artificial magnetic response is one of the recent research topics that is receiving significant attention. Nevertheless, because of the difficulties in exciting not only the magnetic moment but also multipoles of different order, and the presence of losses, the efficiency of its generation is strongly compromised. On the other hand, the presence of a cloaking phenomena can be described in terms of anapole mode, which consists in the compensation of the scattering due to the moment of the electric dipole with the toroidal one. Because of this effect, the remaining part of the field will exhibit a strong(er) magnetic dipole moment response. In the present study, the response of a cloaking device based on a real-life geometry is therefore analysed with particular focus the anapole mode excitation and ideal magnetic dipole behaviour

Hsp60 expression, new locations, functions, and perspectives for cancer diagnosis and therapy

Hsp60 in eukaryotes is considered typically a mitochondrial chaperone (also called Cpn60) but in the last few years it has become clear that it also occurs in the cytosol, the cell surface, the extracellular space, and in the peripheral blood. Studies with prokaryotic models have shown that Hsp60 plays a role in assisting nascent polypeptides to reach a native conformation, and that it interacts with Hsp10 (which also resides in the mitochondria and is also named Cpn10). In addition to its role in polypeptide folding in association with Hsp10, other functions and interacting molecules have been identified for Hsp60 in the last several years. Some of these newly identified functions are associated with carcinogenesis, specifically with tumor cell survival and proliferation. Thus, assessing the levels of Hsp60 in tumor cells and in sera of cancer patients is becoming an attractive area of investigation aiming at the development of means for practical applications in clinical oncology. Since Hsp60 participates in extracellular molecular interactions and cell signalling and also in key intracellular pathways of some types of tumor cells, the idea of using Hsp60 in anti-cancer therapy (chaperonotherapy) is being investigated. The Hsp could be used either as an anticancer agent alone or in combination with tumor antigens, or as target for anti-chaperone compounds. In this article, a brief review is presented of representative research efforts aimed at assessing Hsp60 in a variety of tumors with the purpose of illustrating possible implications and applications for making early and differential diagnoses, assessing prognosis, monitoring response to treatment, and for developing novel anti-cancer strategies