5-year efficacy of all surface laser ablation with cross-linking (ASLA-XTRA) for the treatment of myopia.

The purpose of our study is to examine the long (5-year) efficacy of the all surface laser ablation (ASLA) combined with accelerated cross-linking (CXL) for the treatment of myopia without the use of mitomycin-C (MMC). This retrospective study consisted of 202 eyes of 118 myopic (SD: 2.41, range: - 1.50 to - 12.75 D) patients (44 males, 74 females). Mean age was 28.50 years (SD: 6.45, range: 18 to 51 years) that underwent ASLA with accelerated CXL for the treatment of their myopia. The patients underwent routine postoperative assessment on the 1st, 3rd, 7th day and in the 1st, 3rd, 6th and 12th month, 30th month (±6 months), 4th and 5th year. The mean spherical equivalent (SEq) refractive error changed from - 6.41 ± 2.41 D preoperatively to - 0.02 ± 0.53 D at 5 years postoperatively. The haze score was 0.18, 0.25 and 0.28 at 1, 3 and 6 months postoperatively. At 12 months after the treatment, no eyes had significant corneal haze and in all the following postoperative time intervals the haze traces were gone. ASLA combined with accelerated CXL (ASLA-XTRA) appears to be safe, efficacious and offering very good refractive results. The potential additional benefits of this modality are the stabilizing effect of the refraction and its sterilization effect on the treated cornea without the potential side effects of MMC

Outdoor and indoor path loss modeling at the sub-THz band

In this letter, we present new measurement results to model large-scale path loss at the sub-THz (141-145 GHz) band, for both indoor and outdoor scenarios. Extensive measurement campaigns have been carried out, taking into account both line-of-sight (LoS) and non line-of-sight (NLoS) propagation. For all considered propagation scenarios, existing omni-directional and directional path loss model have been developed, based on the so-called close-in (CI) free-space reference distance model. Moreover, path loss modeling is applied for the 2nd and 3rd strongest multipath components (MPCs). Thus, path loss exponent and large-scale shadow fading estimates are provided. Moreover, power angular spread analysis is depicted, using power angular information up to the 3rd strongest MP

The development of an image processing algorithm for the precise monitoring of a laser-polymer interaction via third harmonic generation microscopy measurements

Insight into the processes taking place upon ultraviolet (UV) laser ablation of polymers is of high importance. In this study, a new algorithm for the precise analysis of third harmonic generation (THG) images from irradiated polymers has been developed. In particular, high accuracy qualitative and quantitative morphological information concerning the induced swelling following UV laser irradiation has been obtained by employing the proposed algorithm. Furthermore, compensation for the curvature of the field, correction of the apparent depth distortion and delineation capability of the total swelling area at a high resolution has been achieved. The above advantages allow a precise and comprehensive monitoring (via the detection of THG signals) of the dynamics during the interaction of laser radiation with polymeric materials to an extent that is not possible with other standard techniques such as profilometry or electron microscopy

VLSI design and implementation of reconfigurable cryptographic systems for symmetric encryption

In this paper a reconfigurable cryptographic system is proposed. The proposed architecture is based on RC5 [1] algorithm standard but it can operate with any cipher. The relationship between the number of block bits, the number of cryptographic rounds (system security), the covered system area resources, and the system's throughput is examined. The proposed cryptographic system is reconfigurable for the number of block bits and the number of cryptographic rounds. These parameters control the system security and the system's throughput. The reconfigurability allows to system adopt temporary parameters in order to be suitable for cryptographic transactions. Finally a parametric VLSI design methodology is proposed for constructing cryptographic systems for symmetric encryption

Nonlinear imaging microscopy for assessing structural and photochemical modifications upon laser removal of dammar varnish on photosensitive substrates

The nonlinear optical microscopy (NLM) modalities of Multi-Photon Excited Fluorescence (MPEF) and Third Harmonic Generation (THG) have been combined in this work to characterize as a function of depth with micrometric resolution the type and extent of morphological and photochemical modifications that take place upon ultraviolet (UV) pulsed laser removal of a dammar varnish layer applied on a photosensitive substrate. The latter consists on a layer of the synthetic polymer polymethyl methacrylate doped with a photosensitizer, the aromatic compound 1,4-di[2-(5-phenyloxazolyl)] benzene, that strongly fluoresces upon UV light illumination. A number of laser conditions for partial or total elimination of the varnish coating were explored, namely different wavelengths (266, 248 and 213 nm) and pulse durations, in the nanosecond, picosecond and femtosecond ranges. Changes in the MPEF signals upon laser ablation of the outermost varnish layer successfully signpost photochemical modifications of the varnish or of the photosensitive under-layer, and their dependence with the laser ablation parameters, i.e., wavelength and pulse duration. In turn, THG signals mark the presence of layer boundaries and the reduction by laser ablation of the thickness of the varnish coating. The obtained MPEF and THG data are complemented by morphological observation by optical microscopy and measurements of laser induced fluorescence and micro-Raman spectra of the samples before and after laser ablation at the selected laser irradiation conditions. The results acquired through these nondestructive NLM imaging techniques serve to understand the phenomena that are induced upon laser ablation and to determine the best operating conditions that ensure controlled removal of the varnish with minimal morphological and chemical modifications to the under-layers. This research is of direct application to the UV pulsed laser cleaning of paintings and demonstrates the potential of NLM as a novel assessment tool for non-destructive, on line monitoring of the laser cleaning process.Peer reviewe

VLSI design and implementation of reconfigurable cryptographic systems for symmetric encryption

In this paper a reconfigurable cryptographic system is proposed. The proposed architecture is based on RC5 [1] algorithm standard but it can operate with any cipher. The relationship between the number of block bits, the number of cryptographic rounds (system security), the covered system area resources, and the system's throughput is examined. The proposed cryptographic system is reconfigurable for the number of block bits and the number of cryptographic rounds. These parameters control the system security and the system's throughput. The reconfigurability allows to system adopt temporary parameters in order to be suitable for cryptographic transactions. Finally a parametric VLSI design methodology is proposed for constructing cryptographic systems for symmetric encryption

Throughput optimization of the cipher message authentication code

A new algorithm for producing message authenticating code (MAC) was recently proposed by NIST. The MAC protects both a message's integrity - by ensuring that a different MAC will be produced if the message has changed - as well as its authenticity - because only someone who knows the secret key could be able to generate a valid MAC. The proposed process incorporates a FIPS approved anti secure block cipher algorithm which was standardized by NIST in May, 2005. The first implementation of the CMAC is presented in this paper. Throughput has been the main design target. The proposed implementation goes one step further introducing an optimized ciphering core to achieve competitive throughput for CMAC, compared to alternative MACs. © 2007 IEEE

Measurement and analysis of UWB radio channel for indoor localization in a hospital environment

This paper focuses on accurate localization of patients in a hospital environment. To reduce power consumption and increase privacy, the localization of patients is only activated in case of an emergency. To evaluate the performance of 'single-shot' localization, ultra-wideband (UWB) radio channel measurements are performed in a modern hospital between a 'mobile agent' and 9 'anchors'. The anchors are placed at existing infrastructure, to allow for easy future integration. The agent is moved over a distance of 40 m at 460 points and spans several furnished rooms and a corridor. The channel is measured from 5 to 10 GHz with a link-budget of 120dB. Using post-processing, the impact of system parameters, like bandwidth and link-budget reduction, on the localization accuracy is evaluated. Our results show that a model based on the logistic distribution yields a higher accuracy, as it more resilient against outliers. The 'single-shot' localization has a mean error of 8.7 cm for a link budget of 110 dB, a bandwidth of 500 MHz, and a carrier frequency of 8.0 GHz. Results show that increasing the bandwidth does not improve the mean localization accuracy. However, reducing the link budget results in a considerably larger mean error

CIPHER BLOCK BASED AUTHENTICATION MODULE: A HARDWARE DESIGN PERSPECTIVE

Message Authentication Codes (MACs) are widely used in order to authenticate data packets, which are transmitted thought networks. Typically MACs are implemented using modules like hash functions and in conjunction with encryption algorithms (like Block Ciphers), which are used to encrypt the transmitted data. However NIST in May 2005 issued a standard, addressing certain applications and their needs, defining a way to implement MACs through FIPS-approved and secure block cipher algorithms. In this paper the best performing implementation of the CMAC standard is presented, in terms of throughput, along with an efficient AES design and implementation