Coupled waveguide model for computing phase and transmission through nanopillar-based metasurfaces.

Dielectric metasurfaces are important in modern photonics due to their unique beam shaping capabilities. However, the standard tools for the computation of the phase and transmission through a nanopillar-based metasurface are either simple, approximating the properties of the surface by that of a single cylinder, or use full 3D numerical simulations. Here we introduce a new analytical model for computing metasurface properties which explicitly takes into account the effect of the lattice geometry. As an example we investigate silicon nanopillar-based metasurfaces, examining how the transmission properties depend on the presence of different modes in the unit cell of the metasurface array. We find that the new model outperforms the isolated cylinder model in predicting the phase, and gives excellent agreement with full numerical simulations when the fill fraction is moderate. Our model offers a waveguide perspective for comprehending metasurface properties, linking it to fiber optics and serving as a practical tool for future metasurface design.

Orders of magnitude loss reduction in photonic bandgap fibers by engineering the core surround.

We demonstrate how to reduce the loss in photonic bandgap fibers by orders of magnitude by varying the radius of the corner strands in the core surround. As a fundamental working principle we find that changing the corner strand radius can lead to backscattering of light into the fiber core. Selecting an optimal corner strand radius can thus reduce the loss of the fundamental core mode in a specific wavelength range by almost two orders of magnitude when compared to an unmodified cladding structure. Using the optimal corner radius for each transmission window, we observe the low-loss behavior for the first and second bandgaps, with the losses in the second bandgap being even lower than that of the first one. Our approach of reducing the confinement loss is conceptually applicable to all kinds of photonic bandgap fibers including hollow core and all-glass fibers as well as on-chip light cages. Therefore, our concept paves the way to low-loss light guidance in such systems with substantially reduced fabrication complexity.

Evolving concepts in ventral hernia repair and physical therapy: prehabilitation, rehabilitation, and analogies to tendon reconstruction.

PURPOSE: The abdominal wall and musculoskeletal tendons share many anatomic, physiologic, and functional characteristics. This review aims to highlight these similar characteristics and to present a rationale why the treatment principles of successful musculoskeletal tendon reconstruction, including principles of surgical technique and physical therapy, can be used in the treatment of complex abdominal wall reconstruction or ventral hernia repair. METHODS: The MEDLINE/PubMed database was used to identify published literature relevant to the purpose of this review. CONCLUSIONS: There are several anatomical and functional similarities between the linea alba and musculoskeletal tendons. Because of this reason, many of the surgical principles for musculoskeletal tendon repair and ventral hernia repair overlap. Distribution of tension is the main driving principle for both procedures. Suture material and configuration are chosen to maximize tension distribution among the tissue edges, as seen in the standard of care multistrand repairs for musculoskeletal tendons, as well as in the small bites for laparotomy technique described in the STITCH trial. Physical therapy is also one of the mainstays of tendon repair, but surprisingly, is not routine in ventral hernia repair. The evidence surrounding physical therapy prehabilitation and rehabilitation protocols in other disciplines is significant. This review challenges the fact that these protocols are not routinely implemented for ventral hernia repair, and presents the rationale and feasibility for the routine practice of physical therapy in ventral hernia repair.

Analytic Mode Normalization for the Kerr Nonlinearity Parameter: Prediction of Nonlinear Gain for Leaky Modes.

Based on the resonant-state expansion with analytic mode normalization, we derive a general master equation for the nonlinear pulse propagation in waveguide geometries that is valid for bound and leaky modes. In the single-mode approximation, this equation transforms into the well-known nonlinear Schrödinger equation with a closed expression for the Kerr nonlinearity parameter. The expression for the Kerr nonlinearity parameter can be calculated on the minimal spatial domain that spans only across the regions of spatial inhomogeneities. It agrees with previous vectorial formulations for bound modes, while for leaky modes the Kerr nonlinearity parameter turns out to be a complex number with the imaginary part providing either nonlinear loss or even gain for the overall attenuating pulses. This nonlinear gain results in more intense pulse compression and stronger spectral broadening, which is demonstrated here on the example of liquid-filled capillary-type fibers.

Analytical mode normalization and resonant state expansion for bound and leaky modes in optical fibers - an efficient tool to model transverse disorder.

We adapt the resonant state expansion to optical fibers such as capillary and photonic crystal fibers. As a key requirement of the resonant state expansion and any related perturbative approach, we derive the correct analytical normalization for all modes of these fiber structures, including leaky modes that radiate energy perpendicular to the direction of propagation and have fields that grow with distance from the fiber core. Based on the normalized fiber modes, an eigenvalue equation is derived that allows for calculating the influence of small and large perturbations such as structural disorder on the guiding properties. This is demonstrated for two test systems: a capillary fiber and a photonic crystal fiber.

Impact of sustained virologic response on risk of type 2 diabetes among hepatitis C patients in the United States.

Data regarding the impact of hepatitis C (HCV) therapy on incidence of type 2 diabetes mellitus are limited. We used the data from the longitudinal Chronic Hepatitis Cohort Study-drawn from four large US health systems-to investigate how response to HCV treatment impacts the risk of subsequent diabetes. Among HCV patients without a history of type 2 diabetes mellitus or hepatitis B, we investigated the incidence of type 2 diabetes from 12 weeks post-HCV treatment through December 2015. Cox proportional hazards models were used to test the effect of treatment status (sustained virologic response [SVR] or treatment failure) and baseline risk factors on the development of diabetes, considering any possible risk factor-by-SVR interactions, and death as a competing risk. Among 5127 patients with an average follow-up of 3.7 years, diabetes incidence was significantly lower among patients who achieved SVR (231/3748; 6.2%) than among patients with treatment failure (299/1379; 21.7%; adjusted hazard ratio [aHR] = 0.79; 95% CI: 0.65-0.96). Risk of diabetes was higher among African American and Asian American patients than White patients (aHR = 1.82 and 1.75, respectively; P < .05), and among Hispanic patients than non-Hispanics (aHR = 1.86). Patients with BMI ≥ 30 and 25-30 (demonstrated higher risk of diabetes aHR = 3.62 and 1.72, respectively; P < .05) than those with BMI < 25; patients with cirrhosis at baseline had higher risk than those without cirrhosis (aHR = 1.47). Among a large US cohort of patients treated for HCV, patients who achieved SVR demonstrated a substantially lower risk for the development of type 2 diabetes mellitus than patients with treatment failure.

FLAIRfusion Processing with Contrast Inversion : Improving Detection and Reading Time of New Cerebral MS Lesions.

PURPOSE: To evaluate the performance of an innovative image processing approach for detection of T2-weighted hyperintense multiple sclerosis (MS) lesions. METHODS: In this study 20 consecutive patients with inflammatory demyelinating lesions were retrospectively evaluated of whom 10 patients featured progressive disease and 10 a stable lesion load. 3 mm transversal FLAIRfusion imaging was processed and archived. Image processing was performed through landmark-based 3D co-registration of the previous and current isotropic FLAIR examination followed by inversion of image contrast. Thereby, the hyperintense signals of the unchanged MS plaques extinguish each other, while newly developed lesions appear bright on FLAIRfusion. Diagnostic performance was evaluated by 4 experienced readers. Consensus reading supplied the reference standard. Sensitivity, specificity, NPV (negative predictive value), PPV (positive predictive value), interreader agreement and reading time were the outcome measures analyzed. RESULTS: Combined sensitivity was 100% at a specificity of 88.2%, with PPV ranging from 83.3% to 90.1% and NPV at 100%. Reading time was nearly 5­fold faster than conventional side by side comparison (35.6 s vs. 163.7 s, p < 0.001). Cohen's kappa was excellent (>0.75; p < 0.001) and Cronbach's alpha was 0.994. CONCLUSION: FLAIRfusion provides reliable detection of newly developed MS lesions along with strong interreader agreement across all levels of expertise in 35 s of reading time.

[Cavernous sinus thrombosis as a rare cause of exophthalmos in childhood : A case report]. / Sinus-cavernosus-Thrombose als seltene Ursache eines Exophthalmus im Kindesalter : Ein Fallbericht.

Complications of acute bacterial sinusitis mostly occur in children and adolescents. In particular, intracranial spread of the infection can lead to severe even fatal courses of the disease. This article is a case report about a 13-year-old boy suffering from left-sided headache, meningismus and exophthalmos as presenting symptoms. Cranial magnetic resonance imaging (MRI) showed merely right-sided sphenoid sinusitis; however, the diffusion-weighted MRI sequence indicated a left-sided cavernous sinus thrombosis, which could be confirmed by computed tomography (CT) angiography. Cerebrospinal fluid diagnostics showed significant leukocytosis confirming secondary meningitis. Finally, exophthalmos was explained by parainfectious cavernous sinus thrombosis and periorbital edema. This case report highlights the importance of extended and specific diagnostic imaging in cases of clinically suspected complications in children and adolescents with sinusitis and the diagnostic significance of diffusion-weighted MRI.

Stereotactic radiosurgery planning of vestibular schwannomas: Is MRI at 3 Tesla geometrically accurate?

PURPOSE: MRI is a mandatory requirement to accurately plan Stereotactic Radiosurgery (SRS) for Vestibular Schwannomas. However, MRI may be distorted due not only to inhomogeneity of the static magnetic field and gradients but also due to susceptibility-induced effects, which are more prominent at higher magnetic fields. We assess geometrical distortions around air spaces and consider MRI protocol requirements for SRS planning at 3 T. METHODS: Hardware-related distortion and the effect of incorrect shimming were investigated with structured test objects. The magnetic field was mapped over the head on five volunteers to assess susceptibility-related distortion in the naso-oro-pharyngeal cavities (NOPC) and around the internal ear canal (IAC). RESULTS: Hardware-related geometric displacements were found to be less than 0.45 mm within the head volume, after distortion correction. Shimming errors can lead to displacements of up to 4 mm, but errors of this magnitude are unlikely to arise in practice. Susceptibility-related field inhomogeneity was under 3.4 ppm, 2.8 ppm, and 2.7 ppm for the head, NOPC region and IAC region, respectively. For the SRS planning protocol (890 Hz/pixel, approximately 1 mm3 isotropic), susceptibility-related displacements were less than 0.5 mm (head), and 0.4 mm (IAC and NOPC). Large displacements are possible in MRI examinations undertaken with lower receiver bandwidth values, commonly used in clinical MRI. Higher receiver bandwidth makes the protocol less vulnerable to sub-optimal shimming. The shimming volume and the CT-MR co-registration must be considered jointly. CONCLUSION: Geometric displacements can be kept under 1 mm in the vicinity of air spaces within the head at 3 T with appropriate setting of the receiver bandwidth, correct shimming and employing distortion correction.

Distribution of disease phase, treatment prescription and severe liver disease among 1598 patients with chronic hepatitis B in the Chronic Hepatitis Cohort Study, 2006-2013.

BACKGROUND: Limited information exists regarding the distribution of disease phases, treatment prescription and severe liver disease among patients with chronic hepatitis B (CHB) in US general healthcare settings. AIM: To determine the distribution of disease phases, treatment prescription and severe liver disease among patients with CHB in general US healthcare settings. METHODS: We analysed demographic and clinical data collected during 2006-2013 from patients with confirmed CHB in the Chronic Hepatitis Cohort Study, an observational cohort study involving patients from healthcare organisations in Michigan, Pennsylvania, Oregon and Hawaii. CHB phases were classified according to American Association for the Study of Liver Disease guidelines. RESULTS: Of 1598 CHB patients with ≥12 months of follow-up (median 6.3 years), 457 (29%) were immune active during follow-up [11% hepatitis B e antigen (HBeAg)-positive, 16% HBeAg-negative, and 2% HBeAg status unknown], 10 (0.6%) were immune tolerant, 112 (7%) were inactive through the duration of follow-up and 886 (55%) were phase indeterminate. Patients with cirrhosis were identified within each group (among 21% of immune active, 3% of inactive and 9% of indeterminate phase patients) except among those with immune-tolerant CHB. Prescription of treatment was 59% among immune active patients and 84% among patients with cirrhosis and hepatitis B virus (HBV) DNA >2000 IU/mL. CONCLUSIONS: Approximately, one-third of the cohort had active disease during follow-up; 60% of eligible patients were prescribed treatment. Our findings underscore the importance of ascertainment of fibrosis status in addition to regular assessment of ALT and HBV DNA levels.

Modern Breeding and Biotechnological Approaches to Enhance Carotenoid Accumulation in Seeds.

There is an increasing demand for carotenoids, which are fundamental components of the human diet, for example as precursors of vitamin A. Carotenoids are also potent antioxidants and their health benefits are becoming increasingly evident. Protective effects against prostate cancer and age-related macular degeneration have been proposed for lycopene and lutein/zeaxanthin, respectively. Additionally, ß-carotene, astaxanthin and canthaxanthin are high-value carotenoids used by the food industry as feed supplements and colorants. The production and consumption of these carotenoids from natural sources, especially from seeds, constitutes an important step towards fortifying the diet of malnourished people in developing nations. Therefore, attempts to metabolically manipulate ß-carotene production in plants have received global attention, especially after the generation of Golden Rice (Oryza sativa). The endosperms of Golden Rice seeds synthesize and accumulate large quantities of ß-carotene (provitamin A), yielding a characteristic yellow color in the polished grains. Classical breeding efforts have also focused in the development of cultivars with elevated seed carotenoid content, with maize and other cereals leading the way. In this communication we will summarize transgenic efforts and modern breeding strategies to fortify various crop seeds with nutraceutical carotenoids.

Higher all-cause hospitalization among patients with chronic hepatitis C: the Chronic Hepatitis Cohort Study (CHeCS), 2006-2013.

In the United States, hospitalization among patients with chronic hepatitis C virus (HCV) infection is high. The healthcare burden associated with hospitalization is not clearly known. We analysed data from the Chronic Hepatitis Cohort Study, an observational cohort of patients receiving care at four integrated healthcare systems, collected from 2006 to 2013 to determine all-cause hospitalization rates of patients with chronic HCV infection and the other health system patients. To compare the hospitalization rates, we selected two health system patients for each chronic HCV patient using their propensity score (PS). Propensity score matching was conducted by site, gender, race, age and household income to minimize differences attributable to these characteristics. We also compared primary reason for hospitalization between chronic HCV patients and the other health system patients. Overall, 10 131 patients with chronic HCV infection and 20 262 health system patients were selected from the 1 867 802 health system patients and were matched by PS. All-cause hospitalization rates were 27.4 (27.0-27.8) and 7.4 (7.2-7.5) per 100 persons-year (PY) for chronic HCV patients and for the other health system patients, respectively. Compared to health system patients, hospitalization rates were significantly higher by site, gender, age group, race and household income among chronic HCV patients (P < 0.001). Compared to health system patients, chronic HCV patients were more likely to be hospitalized from liver-related conditions (RR = 24.8, P < 0.001). Hence, patients with chronic HCV infection had approximately 3.7-fold higher all-cause hospitalization rate than other health system patients. These findings highlight the incremental costs and healthcare burden of patients with chronic HCV infection associated with hospitalization.

An ion trap built with photonic crystal fibre technology.

We demonstrate a surface-electrode ion trap fabricated using techniques transferred from the manufacture of photonic-crystal fibres. This provides a relatively straightforward route for realizing traps with an electrode structure on the 100 micron scale with high optical access. We demonstrate the basic functionality of the trap by cooling a single ion to the quantum ground state, allowing us to measure a heating rate from the ground state of 787 ± 24 quanta/s. Variation of the fabrication procedure used here may provide access to traps in this geometry with trap scales between 100 µm and 10 µm.

Reflectivity enhanced refractive index sensor based on a fiber-integrated Fabry-Perot microresonator.

We discuss a fiber-integrated refractive index sensor with strongly improved detection performance. The resonator has been implemented by means of focused-ion beam milling of a step index fiber and shows a sensitivity of about 1.15µm/RIU. Coating the resonator walls led to a strongly improved mirror reflectivity by a factor of about 26. Design rules for device optimization and a detailed mathematical analysis are discussed, revealing that the sensor operates as an optimized Fabry-Perot resonator. We also show that the performance of such kind of Fabry-Perot sensors is, in general, limited by the detection limit function - a quantity depending on the cavitiy's finesse and on the measurement capabilities used.

APRI and FIB-4 are good predictors of the stage of liver fibrosis in chronic hepatitis B: the Chronic Hepatitis Cohort Study (CHeCS).

We aim to determine the predictive ability of APRI, FIB-4 and AST/ALT ratio for staging of liver fibrosis and to differentiate significant fibrosis (F2-F4) from none to minimal fibrosis (F0-F1) in chronic hepatitis B (CHB). Liver biopsy results were mapped to an F0-4 equivalent fibrosis stage. Mean APRI and FIB-4 scores were significantly higher for each successive fibrosis level from F1 to F4 (P < 0.05). Based on optimized cut-offs, the AUROCs in distinguishing F2-F4 from F0 to F1 were 0.81 (0.76-0.87) for APRI, 0.81 (0.75-0.86) for FIB-4 and 0.56 (0.49-0.64) for AST/ALT ratio. APRI and FIB-4 distinguished F2-F4 from F0 to F1 with good sensitivity and specificity and can be useful for treatment decisions and monitoring progression of fibrosis.

Midinfrared frequency combs from coherent supercontinuum in chalcogenide and optical parametric oscillation.

We observe the coherence of the supercontinuum generated in a nanospike chalcogenide-silica hybrid waveguide pumped at 2 µm. The supercontinuum is shown to be coherent with the pump by interfering it with a doubly resonant optical parametric oscillator (OPO) that is itself coherent with the shared pump laser. This enables coherent locking of the OPO to the optically referenced pump frequency comb, resulting in a composite frequency comb with wavelengths from 1 to 6 µm.

Using thermal boundary conditions to engineer the quantum state of a bulk magnet.

The degree of contact between a system and the external environment can alter dramatically its proclivity to quantum mechanical modes of relaxation. We show that controlling the thermal coupling of cubic-centimeter-sized crystals of the Ising magnet LiHo(x)Y(1-x)F4 to a heat bath can be used to tune the system between a glassy state dominated by thermal excitations over energy barriers and a state with the hallmarks of a quantum spin liquid. Application of a magnetic field transverse to the Ising axis introduces both random magnetic fields and quantum fluctuations, which can retard and speed the annealing process, respectively, thereby providing a mechanism for continuous tuning between the destination states. The nonlinear response of the system explicitly demonstrates quantum interference between internal and external relaxation pathways.

The validity of serum markers for fibrosis staging in chronic hepatitis B and C.

Assessment of liver fibrosis is critical for successful individualized disease management in persons with chronic hepatitis B (CHB) or chronic hepatitis C (CHC). We expanded and validated serum marker indices to provide accurate, reproducible and easily applied methods of fibrosis assessment. Liver biopsy results from over 284 CHB and 2304 CHC patients in the Chronic Hepatitis Cohort Study ('CHeCS') were mapped to a F0-F4 equivalent scale. APRI and FIB-4 scores within a 6-month window of biopsy were mapped to the same scale. A novel algorithm was applied to derive and validate optimal cut-offs for differentiating fibrosis levels. For the prediction of advanced fibrosis and cirrhosis, the FIB-4 score outperformed the other serum marker indices in the CHC cohort and was similar to APRI in the CHB cohort. The area under the receiver operating characteristic curves (AUROC) for FIB-4 in differentiating F3-F4 from F0-F2 was 0.86 (95% CI: 0.80-0.92) for CHB and 0.83 (95% CI: 0.81-0.85) for CHC. The suggested cut-offs based on FIB-4 model produced high positive predictive values [CHB: 90.0% for F0-F2, 100.0% for cirrhosis (F4); CHC: 89.7% for F0-F2; 82.9% for cirrhosis (F4)]. In this large observational cohort, FIB-4 predicted the upper and lower end of liver fibrosis stage (cirrhosis and F0-F2, respectively) with a high degree of accuracy in both CHB and CHC patients.

Taking a deep look: modern microscopy technologies to optimize the design and functionality of biocompatible scaffolds for tissue engineering in regenerative medicine.

This review focuses on modern nonlinear optical microscopy (NLOM) methods that are increasingly being used in the field of tissue engineering (TE) to image tissue non-invasively and without labelling in depths unreached by conventional microscopy techniques. With NLOM techniques, biomaterial matrices, cultured cells and their produced extracellular matrix may be visualized with high resolution. After introducing classical imaging methodologies such as µCT, MRI, optical coherence tomography, electron microscopy and conventional microscopy two-photon fluorescence (2-PF) and second harmonic generation (SHG) imaging are described in detail (principle, power, limitations) together with their most widely used TE applications. Besides our own cell encapsulation, cell printing and collagen scaffolding systems and their NLOM imaging the most current research articles will be reviewed. These cover imaging of autofluorescence and fluorescence-labelled tissue and biomaterial structures, SHG-based quantitative morphometry of collagen I and other proteins, imaging of vascularization and online monitoring techniques in TE. Finally, some insight is given into state-of-the-art three-photon-based imaging methods (e.g. coherent anti-Stokes Raman scattering, third harmonic generation). This review provides an overview of the powerful and constantly evolving field of multiphoton microscopy, which is a powerful and indispensable tool for the development of artificial tissues in regenerative medicine and which is likely to gain importance also as a means for general diagnostic medical imaging.