Temperature-Compensated Solution Concentration Measurements Using Photonic Crystal Fiber-Tip Sensors.

We demonstrate fiber optic sensors with temperature compensation for the accurate measurement of ethanol concentration in aqueous solutions. The device consists of two photonic crystal (PhC) fiber-tip sensors: one measures the ethanol concentration via refractive index (RI) changes and the other one is isolated from the liquid for the independent measurement of temperature. The probes utilize an optimized PhC design providing a Lorentzian-like, polarization-independent response, enabling a very low imprecision (pm-level) in the wavelength determination. By combining the information from the two probes, it is possible to compensate for the effect that the temperature has on the concentration measurement, obtaining more accurate estimations of the ethanol concentration in a broad range of temperatures. We demonstrate the simultaneous and single-point measurements of temperature and ethanol concentration in water, with sensitivities of 19 pm/°C and ∼53 pm/%, in the ranges of 25 °C to 55 °C and 0 to 50% (at 25 °C), respectively. Moreover, a maximum error of 1.1% in the concentration measurement, with a standard deviation of ≤0.8%, was obtained in the entire temperature range after compensating for the effect of temperature. A limit of detection as low as 0.08% was demonstrated for the concentration measurement in temperature-stable conditions.

Handheld NIR Spectral Sensor Module Based on a Fully-Integrated Detector Array.

For decades, near-infrared (NIR) spectroscopy has been a valuable tool for material analysis in a variety of applications, ranging from industrial process monitoring to quality assessment. Traditional spectrometers are typically bulky, fragile and expensive, which makes them unsuitable for portable and in-field use. Thus, there is a growing interest for miniaturized, robust and low-cost NIR sensors. In this study, we demonstrate a handheld NIR spectral sensor module, based on a fully-integrated multipixel detector array, sensitive in the 850-1700 nm wavelength range. Differently from a spectrometer, the spectral sensor measures a limited number of NIR spectral bands. The capabilities of the spectral sensor module were evaluated alongside a commercially available portable spectrometer for two application cases: to quantify the moisture content in rice grains and to classify plastic types. Both devices achieved the two sensing tasks with comparable performance. Moisture quantification was achieved with a root mean square error (RMSE) prediction of 1.4% and 1.1% by the spectral sensor and spectrometer, respectively. Classification of the plastic type was achieved with a prediction accuracy on unknown samples of 100% and 96.4% by the spectral sensor and spectrometer, respectively. The results from this study are promising and demonstrate the potential for the compact NIR modules to be used in a variety of NIR sensing applications.

Modeling a grating coupler-based interferometer for far-field-sensing of nanoscale displacements.

Sensing displacements at the nanoscale is the basis for many metrology applications, in particular atomic-force microscopy. Displacement sensing with nano-optomechanical structures provides interesting opportunities for integration, but it typically features a small dynamic range due to the near-field nature of the sensor-sample interaction. Here, a far-field sensing approach based on a grating coupler is considered and an analytical model used to tune its performance is introduced. The proposed model allows exploiting the full range of design parameters and thereby optimizing resolution and dynamic range. The compact size of the sensor and the possibility of integrating it with an on-chip laser and detector make it very promising for fully-integrated optical sensing systems.

Non-Lorentzian Local Density of States in Coupled Photonic Crystal Cavities Probed by Near- and Far-Field Emission.

Recent theories proposed a deep revision of the well-known expression for the Purcell factor, with counterintuitive effects, such as complex modal volumes and non-Lorentzian local density of states. We experimentally demonstrate these predictions in tailored coupled cavities on photonic crystal slabs with relatively low optical losses. Near-field hyperspectral imaging of quantum dot photoluminescence is proved to be a direct tool for measuring the line shape of the local density of states. The experimental results clearly evidence non-Lorentzian character, in perfect agreement with numerical and theoretical predictions. Spatial maps with deep subwavelength resolution of the real and imaginary parts of the complex mode volumes are presented. The generality of these results is confirmed by an additional set of far-field and time-resolved experiments in cavities with larger modal volume and higher quality factors.

Multimode photonic molecules for advanced force sensing.

We propose a force sensor, with optical detection, based on a reconfigurable multi-cavity photonic molecule distributed over two parallel photonic crystal membranes. The system spectral behaviour is described with an analytical model based on coupled mode theory and validated by finite difference time domain simulations. The deformation of the upper photonic crystal membrane, due to a localized vertical force, is monitored by the relative spectral positions of the photonic molecule resonances. The proposed system can act both as force sensor, with pico-newton sensitivity, able to identify the position where the force is applied, and as torque sensor able to measure the torsion of the membrane along two perpendicular directions.

Nano-opto-electro-mechanical switch based on a four-waveguide directional coupler.

Optical switches connect optical circuits, and route optical signals in networks. Nano-electromechanical systems can in principle enable compact and power-effective switches that can be integrated in photonic circuits. We proposed an optical switch based on four coupled waveguides arranged in three-dimensional configuration. The switching operation is controlled by a cantilever displacement of only 55 nm. Simulations show that our proposed device requires a low switching voltage down to 3V and can operate at frequencies in the MHz range. Our results also pave the way towards novel optical components that electromechanically manipulate light in both the horizontal and the vertical direction in photonic circuits.

Coherent Atom-Phonon Interaction through Mode Field Coupling in Hybrid Optomechanical Systems.

We propose a novel type of optomechanical coupling which enables a tripartite interaction between a quantum emitter, an optical mode, and a macroscopic mechanical oscillator. The interaction uses a mechanism we term mode field coupling: a mechanical displacement modifies the spatial distribution of the optical mode field, which, in turn, modulates the emitter-photon coupling rate. In properly designed multimode optomechanical systems, we can achieve situations in which mode field coupling is the only possible interaction pathway for the system. This enables, for example, swapping of a single excitation between emitter and phonon, creation of nonclassical states of motion, and mechanical ground-state cooling in the bad-cavity regime. Importantly, the emitter-phonon coupling rate can be enhanced through an optical drive field, allowing active control of the emitter-phonon coupling for realistic experimental parameters.

Photon-counting and analog operation of a 24-pixel photon number resolving detector based on superconducting nanowires.

We investigate the transition from the photon-counting to the linear operation mode in a large-dynamic range photon-number-resolving-detector (PNRD). A 24-pixel photon-number-resolving-detector, based on superconducting nanowires in a series configuration, has been fabricated and characterized. The voltage pulses, generated by the pixels, are summed up into a single readout pulse whose height is proportional to the detected photon number. The device can resolve up to twenty-five distinct output levels corresponding to the detection of n = 0-24 photons. Due to its large dynamic range, high sensitivity, high speed and wide wavelength range, this device has potential for linear detection in the few tens of photons range. We show its application in the detection of analog optical signals at frequencies up to few hundred MHz and investigate the limits related to the finite number of pixels and to the pixel's dead time.

Engineering of light confinement in strongly scattering disordered media.

Disordered photonic materials can diffuse and localize light through random multiple scattering, offering opportunities to study mesoscopic phenomena, control light-matter interactions, and provide new strategies for photonic applications. Light transport in such media is governed by photonic modes characterized by resonances with finite spectral width and spatial extent. Considerable steps have been made recently towards control over the transport using wavefront shaping techniques. The selective engineering of individual modes, however, has been addressed only theoretically. Here, we experimentally demonstrate the possibility to engineer the confinement and the mutual interaction of modes in a two-dimensional disordered photonic structure. The strong light confinement is achieved at the fabrication stage by an optimization of the structure, and an accurate and local tuning of the mode resonance frequencies is achieved via post-fabrication processes. To show the versatility of our technique, we selectively control the detuning between overlapping localized modes and observe both frequency crossing and anti-crossing behaviours, thereby paving the way for the creation of open transmission channels in strongly scattering media.

Superconducting series nanowire detector counting up to twelve photons.

We demonstrate a superconducting photon-number-resolving detector capable of resolving up to twelve photons at telecommunication wavelengths. It is based on a series array of twelve superconducting NbN nanowire elements, each connected in parallel with an integrated resistor. The photon-induced voltage signals from the twelve elements are summed up into a single readout pulse with a height proportional to the detected photon number. Thirteen distinct output levels corresponding to the detection of n = 0-12 photons are observed experimentally. A detailed analysis of the linearity and of the excess noise shows the potential of scaling to an even larger dynamic range.

Integrated autocorrelator based on superconducting nanowires.

We demonstrate an integrated autocorrelator based on two superconducting single-photon detectors patterned on top of a GaAs ridge waveguide. This device enables the on-chip measurement of the second-order intensity correlation function g(2)(τ). A polarization-independent device quantum efficiency in the 1% range is reported, with a timing jitter of 88 ps at 1300 nm. g(2)(τ) measurements of continuous-wave and pulsed laser excitations are demonstrated with no measurable crosstalk within our measurement accuracy.

Ultrasensitive N-photon interferometric autocorrelator.

We demonstrate a novel method to measure Nth-order (N=1,2,3,4) interferometric autocorrelation with high sensitivity and temporal resolution. It is based on the combination of linear absorption and nonlinear detection in a superconducting nanodetector, providing much higher efficiency than methods based on all-optical nonlinearities. Its temporal resolution is only limited by the quasiparticle energy relaxation time, which is directly measured to be in the 20 ps range for the NbN films used in this work. We present a general model of interferometric autocorrelation with these nonlinear detectors and discuss the comparison with other approaches and possible improvements.

CXCR4/YY1 inhibition impairs VEGF network and angiogenesis during malignancy.

Tumor growth requires neoangiogenesis. VEGF is the most potent proangiogenic factor. Dysregulation of hypoxia-inducible factor (HIF) or cytokine stimuli such as those involving the chemokine receptor 4/stromal-derived cell factor 1 (CXCR4/SDF-1) axis are the major cause of ectopic overexpression of VEGF in tumors. Although the CXCR4/SDF-1 pathway is well characterized, the transcription factors executing the effector function of this signaling are poorly understood. The multifunctional Yin Yang 1 (YY1) protein is highly expressed in different types of cancers and may regulate some cancer-related genes. The network involving CXCR4/YY1 and neoangiogenesis could play a major role in cancer progression. In this study we have shown that YY1 forms an active complex with HIF-1alpha at VEGF gene promoters and increases VEGF transcription and expression observed by RT-PCR, ELISA, and Western blot using two different antibodies against VEGFB. Long-term treatment with T22 peptide (a CXCR4/SDF-1 inhibitor) and YY1 silencing can reduce in vivo systemic neoangiogenesis (P < 0.01 and P < 0.05 vs. control, respectively) during metastasis. Moreover, using an in vitro angiogenesis assay, we observed that YY1 silencing led to a 60% reduction in branches (P < 0.01) and tube length (P < 0.02) and a 75% reduction in tube area (P < 0.001) compared with control cells. A similar reduction was observed using T22 peptide. We demonstrated that T22 peptide determines YY1 cytoplasmic accumulation by reducing its phosphorylation via down-regulation of AKT, identifying a crosstalk mechanism involving CXCR4/YY1. Thus, YY1 may represent a crucial molecular target for antiangiogenic therapy during cancer progression.

Proposal for a superconducting photon number resolving detector with large dynamic range.

We propose a novel photon number resolving detector structure with large dynamic range. It consists of the series connection of N superconducting nanowires, each connected in parallel to an integrated resistor. Photon absorption in a wire switches its current to the parallel resistor producing a voltage pulse and the sum of these voltages is measured at the output. The combination of this structure and a high input impedance preamplifier result in linear, high fidelity, and fast photon detection in the range from one to several tens of photons.

Widely tunable, efficient on-chip single photon sources at telecommunication wavelengths.

We demonstrate tunable on-chip single photon sources using the Stark tuning of single quantum dot (QD) excitonic transitions in short photonic crystal waveguides (PhC WGs). The emission of single QDs can be tuned in real-time by 9 nm with an applied bias voltage less than 2V. Due to a reshaped density of optical modes in the PhC WG, a large coupling efficiency ß ≥ 65%to the waveguide mode is maintained across a wavelength range of 5 nm. When the QD is resonant with the Fabry-Perot mode of the PhC WG, a strong enhancement of spontaneous emission is observed leading to a maximum coupling efficiency ß = 88%. These results represent an important step towards the scalable integration of single photon sources in quantum photonic integrated circuits.

Antibiotic prophylaxis in catheter-associated urinary infections.

This study aimed to assess the usefulness of antibiotic prophylaxis with Levofloxacin (LVFX) in short and mediumterm catheterisations. This study was developed to evaluate and confirm the effectiveness and need for prophylaxis in preventing catheter-associated UTIs, using LVFX at a dose of 250 mg administered orally to patients who had been subjected to short and medium-term urinary bladder catheterisation following surgery (3-14 days). The study was designed as a phase III study with parallel groups, multicentre, randomised, controlled with a placebo in three groups. The study was double-blind in treatment groups A and B and single-blind in group C. The study involved the recruitment of 120 patients, 40 for each treatment group. We show two types of results, one based on primary effectiveness variables and the other on the secondary effectiveness variables. The group treated with LVFX displayed a greater tendency toward the negativisation of bacteriuria and pyuria tests than that recorded for the placebo group, and was essentially comparable to that recorded for the group of patients treated with Ciprofloxacin. We can thus affirm that LVFX may be useful for preventing short and medium-term CAUTIs.

Benign thyroid disease: treatment notes.

AIM: The treatment of benign thyroid disease is a topic widely debated, ranging from "Lobectomy" to "Total Thyroidectomy". This study aims to contribute to the thinking on treatment strategies for benign thyroid disease. MATERIALS OF STUDY: Thirty five patients underwent surgical treatment following the pre-surgical diagnosis of benign thyroid disease between 2003 and 2005 at the Complex Unit of General and Geriatric Surgery at the Second University of Naples (S.U.N.). In 26 cases total thyroidectomies were performed, in 3 subtotal thyroidectomies, in 6 simple lobectomies. DISCUSSION: Post-surgical course was optimal in the majority of cases. The large number of total thyroidectomies performed is consistent with the trend favoured by this type of strategy. When backed by FNA, non-radical surgery can be opted with greater confidence for single nodules and when surgical risks are high. The refinement of surgical techniques and directions for the identifying and preparing the recurrent nerve have enabled a radical approach in treating thyroid nodular disease. CONCLUSIONS: In our opinion, for a solitary nodule with residual diseased parenchyma we believe total thyroidectomy should be prescribed. If, however, the residual parenchyma is unharmed a lobectomy may be considered. In conclusion, we recommend the individual assessment of each pathology, though we favour total thyroidectomy.

Clinical considerations on the retroperitoneal liposarcomas.

AIM: It presents a clinical case of undifferentiated retroperitoneal liposarcoma with 5 years' recurrence from the first operation for the rarity of the occurrence, the problems related to surgery and complementary therapeutic approach. MATERIAL OF STUDY: Male patient aged 73 was operated for removal of retroperitoneal mass with involvement of the right kidney at the Second University of Naples in the 2003. In accordance with the interdisciplinary board, complementary therapy is not indicated and follow-up program. The successive controls were negative until at least 2007. Reoperation for recurrence in 2008 for the presence of massive bone formation occupying a large part in the right half of the abdomen at the sub-hepatic level. In both cases histological examination showed undifferentiated liposarcoma. DISCUSSION: It is of unknown etiology and only 25% occurs in well-differentiated cells are also more than 100 histological subtypes, 85% are malignant. The most affected is the male sex and from the beginning looks like malignancy. The trend of growth in general is slow, and in most cases tends to recur over time. The role of chemotherapy and radiation therapy is controversial. CONCLUSIONS: The peculiarity of our case is higher than the average survival despite advanced age and presence of recurrence. This confirms the importance of surgical treatment, thus offering the patient a chance of better long-term survival.

The surgical treatment of benign breast lesions in young adolescents.

AIM: There is much controversy surrounding the treatment of benign breast lesions in young adolescents: on one side the need for surgical treatment and on the other doubts in regard to operating on young patients with a benign disease. Another element sparking the debate is the correlation between the appearance of fibroadenomas and the presence of elevated prolactin levels in the blood. MATERIAL OF STUDY: 42 patients between the ages of 14 and 21 being treated at the General surgery and Geriatrics Unit of the Department of Gerontology, Geriatrics and Metabolic Diseases at the Second University of Naples between 2001 and 2004. In addition, blood prolactin levels were measured in 24 patients. RESULTS: Only 4.76% of the patients examined (2 cases) had a family history of breast tumours. Out of a total of 42 adolescent patients that were operated on, we detected fibroadenomas in 35 (83.34%), fibrocystic disease in 3 (7.14%), adenosis in 3 patients (7.14%) and a phylloid tumour in 1 (2.38%). Blood prolactin was measured in 24 patients and in 17 cases we detected increased plasmatic levels of this hormone; in addition, anamneses revealed that of these 17 patients, 9 were using oral contraceptives. DISCUSSION: The most common cause of palpable breast masses in adolescents under 21 years of age are fibroadenomas. The connection to hormonal, genetic and family factors is still unknown, both during the genesis of this pathology and as concerns an increased risk of possible malignant development. The correlation between fibroadenomas and elevated prolactin serum levels still remains controversial today. Various studies, measuring the blood concentration of prolactin in many patients have demonstrated that both elevated blood levels of this hormone and the use of oral contraceptives play a role in the development and growth of benign breast lesions. CONCLUSION: Fortunately, breast disease is rare in adolescents; these patients do not often develop nodules and where these do occur the vast majority of cases involve benign lesions. A thorough follow-up on patients with nodular breast lesions is thus useful. As concerns the connection between prolactin and fibroadenomas, we also reported interesting data; this represents 70.83% of our subjects. KEYWORDS: Blood prolactin levels, Fibroadenomas, Surgical treatment.

NIM vs Neurosign in nerve sparing total thyroidectomy. Multicentric experience.

INTRODUCTION: Injury to cranial nerve represents 5% of negligence litigation against general surgeons and of all malpractice jury verdicts in endocrine surgery 60% accounts for recurrent nerve injuries and 15% for anoxic brain injuries from RLN injuries, unrecognized post-operatively. During Total Thyroidectomy is reported an incidence of failure to find the nerve in 5- 18% of cases and if we think that routine identification of the RLN during thyroid surgery has reduced the injury rate from 10% to less than 4% and that the incidence of nerve paralysis was 3 to 4 times greater in cases where the nerve was not exposed than in cases where was routinely exposed, then we understand the importance of a clear identification during every thyroid dissection MATERIALS AND METHODS: 880 Total Thyroidectomies during the last 4 years, since Jannuary 2007 until December 2010, (610 F, 270 M; mean age 44,5 years old, range 14-83). All patients were examined pre and postoperatively (1-6 months after) by direct laryngoscopy or laryngofibroscopy to check vocal cord mobility (medium follow up 25.5 months range 3-50 months). The Authors reviewed charts from two randomized groups, selected by a double blind, statistically designed study and again compared in a multivariate analysis (Stat 2004 ltd): 1) 480 total sutureless thyroidectomies, performed during the previous year with continuous intra-operative nerve monitoring using dedicated endotracheal tube with a last generation Nerve Integrity Monitor Pulse II (N.I.M. pulse II®) 2) 400 total sutureless thyroidectomies: performed with continuous intra-operative nerve monitoring using dedicated Laryngeal Electrode, a self-adhesive device designed to fit onto standard reinforced endotracheal tubes (Neurosign® 1040 - 4 Channel EMG) RESULTS: There were no statistically significative difference between the two groups for distribution of age, sex, epidemiological characteristics, type of pathology etc. The incidence of major complications in thyroid surgery in the first two groups (total Thyroidectomy performed by NIM and by Neurosign), as well as compared with the data of the literature are absolutely overimposable; only significative difference is a reduction of the costs in the second group (Neurosign). The 1st group (NIM) specificity is 90.2% (433/480). There were 6 cases of temporary RLN paralysis (temporary paralysis rate: 1.25 % of patients), 3 true positive and 3 false negative. Finally there were 3 cases of permanent RLN paralysis (0.75%), 2 truepositive and 1 false-negative developed after 10 days (demyelination by thermal injury). The 2nd group (Neurosign) specificity of 89 % (356/400). There were 6 cases of temporary RLN paralysis (rate: 1.5 %, p > 0.5), 2 true positive, 1 false positive and 4 false negative. Finally 2 cases of permanent RLN paralysis (0.5% p > 0.5), 2 true-positive. DISCUSSION AND CONCLUSION: Our data confirm a useful application of NIM and Neurosign in thyroid dissection nerve prevention. We don't believe that those procedures can be useful for learning thyroid gland surgery, because can't preserve from an accurate dissection and nerve identification technique, but can only support in nerve-at-risk thyroidectomy or during dissection can support expert surgeon's decision, having a clear pre-operative (post-anesthesiologist) and post-operative predictive value. Those procedures are anyway expensive and time consuming (25000-30000 € for the E.M.G. system and almost 200-250 € for each dedicated endotracheal tube in NIM group). So Neurosign group has over-imposable results in terms of complications specificity and accurancy (no statistically significative differences), but it's a much cheaper procedure!