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The Daniel K. Inouye Solar Telescope (DKIST) Visible Spectro-Polarimeter (ViSP) is a traditional slit-scanning spectrograph with the ability to observe solar regions up to a $120\times 78~\mbox{arcsec}^{2}$ 120 × 78 arcsec 2 area. The design implements dual-beam polarimetry, a polychromatic polarization modulator, a high-dispersion echelle grating, and three spectral channels that can be automatically positioned. A defining feature of the instrument is its capability to tune anywhere within the 380 – 900 nm range of the solar spectrum, allowing for a virtually infinite number of combinations of three wavelengths to be observed simultaneously. This enables the ViSP user to pursue well-established spectro-polarimetric studies of the magnetic structure and plasma dynamics of the solar atmosphere, as well as completely novel investigations of the solar spectrum. Within the suite of first-generation instruments at the DKIST, ViSP is the only wavelength-versatile spectro-polarimeter available to the scientific community. It was specifically designed as a discovery instrument to explore new spectroscopic and polarimetric diagnostics and test improved models of polarized line formation through high spatial-, spectral-, and temporal-resolution observations of the Sun’s polarized spectrum. In this instrument article, we describe the science requirements and design drivers of ViSP and present preliminary science data collected during the commissioning of the instrument.

We present the Tenerife Inversion Code (TIC), which has been developed to infer the magnetic and plasma properties of the solar chromosphere and transition region via full-Stokes inversion of polarized spectral lines. The code is based on the HanleRT forward engine, which takes into account many of the physical mechanisms that are critical for a proper modeling of the Stokes profiles of spectral lines originating in the tenuous and highly dynamic plasmas of the chromosphere and transition region: quantum level population imbalance and interference (atomic polarization), frequency coherence effects in polarized resonance scattering (partial frequency redistribution), and the impact of arbitrary magnetic fields on the atomic polarization and the radiation field. We present first results of atmospheric and magnetic inversions, and discuss future developments for the project., Comment: 17pages, 7 figures. Accepted for publication in The Astrophysical Journal

We report on the fabrication and electrical characterization of Schottky diodes on epitaxial relaxed germanium for THz detection, which implement both a sub-micron junction area and the air-bridge technology. The small footprint necessary for low capacitances and T-shaped contacts are obtained by using a triple layer of electronic resists with different sensitivity. The cross-sectional analyses revealed a clearly suspended air-bridge and the T-shape of the metal contact with footprint width below 400 nm. The electrical characterization at room temperature shows well defined Schottky diode behavior with ideality factor between 1 and 2 and low series resistance suitable for THz detection.

In this paper we present design, fabrication and characterization of Schottky terahertz diodes. The diode is based on a Ti/n-GaAs junction with very low junction capacitance. T-gate technology, based on trilayer of electronic resists and electron-beam lithography, and air-bridge technique have been used to obtain Schottky diodes with cutoff frequency in the THz range. The device fabrication process is fully planar and suitable for integration in monolithic arrays for active spectroscopic imaging.

The paper deals with the problem of early detecting cracks in composite materials for avionic applications. In particular, the authors present a THz imaging system that exploits compressive sampling (CS) to detect submillimeter cracks with a reduced measurement burden. Traditional methods for THz imaging usually involve raster scan of the issue of interest by means of highly collimated radiations and the corresponding image is achieved by measuring the received THz power in different positions (pixels) of the desired image. As it can be expected, the higher the required resolution, the longer the measurement time. On the contrary, two different approaches for THz imaging (namely, continuous wave and time domain spectroscopy) combined with a proper CS solution are used to assure as good results as those granted by traditional raster scan; a proper set of masks (each of which characterized by a specific random pattern) are defined to the purpose. A number of tests conducted on simulated data highlighted the promising performance of the proposed method thus suggesting its implementation in an actual measurement setup.

We investigate new classes of artificial materials exhibiting unconventional properties in order to build novel devices operating in the Terahertz regime. The design, fabrication and electromagnetic characterization of tunable metamaterials with unit cells based on Split Ring Resonators are presented. By incorporation of a nematic liquid crystal in the structure, we observe a frequency shift in the resonant response over 10% in bandwidth and more than 10 dB change in the signal absorption. We discuss how such a hybrid structure can be exploited for the development of a THz spatial light modulator.

Prevalence, awareness, treatment and control of hypertension were assessed in 1032 (90%) of 1147 elderly (or = 65 years) inhabitants of three Italian villages. Blood pressure (BP) was measured at home on two separate occasions following a standardised protocol. Persons taking antihypertensive drugs or with BP valuesor = 140/90 mm Hg were considered as affected by hypertension. Prevalence of hypertension was 64.8%, with higher rates in women than men, and in those aged 75-84 than in those aged 65-74. Diabetes, strokes and hypercholesterolaemia were more frequent in hypertensive than normotensive people, whereas cardiac diseases, overweight and smoking did not differ significantly between hypertensive and normotensive people. Of the 669 hypertensive patients, 439 (65.6%) were aware of their hypertension, 398 (59.5%) were being treated, and 70 (10.5%) had their hypertension controlled. Of the 230 unaware patients, 201 (87.4%) had had their BP measured in the previous year. Of these, 174 (86.6%) had stage 1 hypertension, while 27 had stage 2 hypertension with SBP values170 mm Hg. Overall, the patients with stage 1 hypertension accounted for 68.3% of the untreated and 50.5% of the treated patients. The use of a single drug was more frequent in patients with controlled (97.1%) or stage 1 (97.0%) than with stages 2-3 (18.9%) hypertension. The drugs prescribed most were angiotensin-converting enzyme (ACE) inhibitors (45%), followed by diuretics (43%). As our findings suggest that BP values can be effectively reduced by treating or increasing drug treatment in stage 1 hypertensive patients, data on safety and effectiveness of this policy are urgently needed. Journal of Human Hypertension (2000) 14, 825-830

The theory of formation of hydrogen lines in the presence of stationary electric and magnetic fields is applied to the calculation of the emerging Stokes profiles from a slab of hydrogen plasma, for different optical thicknesses of the slab. The calculations are performed assuming different analytical dependences of the source function on the optical depth. Typical results for hydrogen lines of interest in solar plasmas investigation are then shown.

We have fabricated AlGaAs/InGaAs/AlGaAs heterostructure field effect transistors (HFET) with integrated on-chip antennas and we have measured their optical responsivity when mounted in a in-house developed quasi-optical package with a silicon substrate lens.

We present the realization of high electron mobility transistors on GaN-heterostructures usable for mixing and rectification in the THz range. Device fabrication is fully compatible with industrial processes employed for millimetre wave integrated circuits. On-chip, integrated, polarization-sensitive, planar antennas were designed to allow selective coupling of THz radiation to the three terminals of field effect transistors in order to explore different mixing schemes for frequencies well above the cutoff frequency for amplification. The polarization dependence of the spectral response in the 0.18-0.40 THz range clearly demonstrated the possible use as integrated heterodyne mixers.

The main properties of the first- and second-order moments of polarized hydro-gen lines, forming in the presence of stationary electric and magnetic fields, are reviewed. The analytical results presented here apply directly to the case of optically-thin emission lines in the LTE regime. Some applications of such results to electric- and magnetic-field diagnostics in (solar) plasmas are then briefly considered.

Cases are described with Leber's optic atrophy and neurological symptoms and/or MRI lesions suggestive of multiple sclerosis. We describe a case of a young woman with Devic's neuromyelitis optica and 3460 homoplasmic mitochondrial DNA mutation.

Rectification at room temperature by asymmetric double-grating-gate GaAs-based field effect transistors has been observed up to 3.89 THz at zero drain bias, and attributed to the peculiar unequal spacing among the two gratings.

We demonstrate a rectification mechanism based on quantum tunneling through the narrow Schottky barrier of a sub-micrometric Au/Ti/n-GaAs junction, which is capable of efficient power detection of free-space terahertz radiation beams even without an applied dc bias. Three-dimensional shaping of the junction geometry provides an enhanced zero-bias tunneling probability due to increased electric fields at the junction, resulting in cutoff frequencies up to 0.55 THz, responsivity up to 200 V/W, and noise equivalent power better than 10^-9 W/sqrt(Hz) without applied dc bias.

We fabricated GaAs air-bridge Schottky diodes and pseudomorphic InGaAs/AlGaAs heterostructure field-effect transistors with similar on-chip lithographic antennas. Detectors were packaged with a silicon lens and their rectified signal when exposed to 450-700 GHz radiation was compared. © 2011 IEEE.

The beam of planar THz Schottky detectors is strongly concentrated in the dielectric half-space. With the goal of illuminating arrays from the free-space side, we started to investigate substrate removal from both GaAs and Ge-on-Si diode wafers. © 2011 IEEE.

Imaging sensors employing sub-millimeter waves and terahertz radiation (frequencies from 100 to 3000 GHz) are needed for security applications requiring stand-off, non-destructive sensing, due to its much larger penetration depth into dielectric materials. © 2011 Springer Science+Business Media B.V.

Foreseen operation at sub-THz frequencies of Schottky contacts for diodes and transistor gates on GaAs based heterostructures requires area reduction down to 0.1×1 microns, and wet chemical processes. We report on the compatibility of Trilayer Electron-beam Lithography with such wet processes. © 2010 IEEE.

Objective: Insulin resistance (IR) increases during puberty in normal children. IR is the first adverse metabolic event of obesity, and the marker of the metabolic syndrome. We aimed to study the effect of puberty on IR in obese and normal-weight children. Design: Cross-sectional evaluation of fasting glucose, insulin concentrations, and homeostasis model assessment of IR (HOMA-IR) in obese and control children throughout puberty. Patients and methods: We recruited 424 obese children (207 pre-pubertal and 217 pubertal divided in Tanner stages 2–3, 4, and 5) and estimated IR using the HOMA-IR index. Data were compared to those obtained in 123 healthy normal-weight children (40 pre-pubertal and 83 pubertal divided in Tanner stages 2–3, 4, and 5). Results: In the obese children mean HOMA-IR increased progressively across Tanner stages, and was significantly higher in all groups (pre-pubertal and Tanner stages 2–3, 4, and 5) of obese than in control children. HOMA-IR was significantly correlated with BMI. Conclusions: HOMA-IR in obese children increases at puberty more than in normal-weight children and does not return to pre-pubertal values at the end of puberty.

We investigate the use of Terahertz Time Domain Spectroscopy as a tool for the measurement of the index dispersion of multi walled carbon nanotubes in polypropylene based composites. Samples containing 0.5% by volume concentration of not functionalized and functionalized carbon nanotubes are prepared by melt compounding technology. Results indicate that the THz response of the investigated nanocomposites is strongly dependent on the kind of nanotube functionalization, which in turn impacts on the level of dispersion inside the polymer matrix. We show that specific dielectric parameters such as the refractive index and the absorption coefficient measured by THz spectroscopy can be both correlated to the index of dispersion as estimated using a traditional and well established approach based on the analysis of optical microscopy images performed on purpose-prepared nanocomposite slices.

The unlimited availability of GH obtained by recombinant DNA technology has allowed optimization of treatment in GH-deficient (GHD) children. At the same time it has prompted a number of studies in conditions not characterized by GHD such as Turner syndrome, intrauterine growth retardation, chronic renal failure and other chromosomal and genetic abnormalities associated with short stature. Several controlled and uncontrolled studies have now reported the adult height of patients with short stature and normal GH secretion. Critical reviewing of the data shows that some short non-GHD children may benefit from a prolonged treatment with GH. However, further studies are needed in order to be able to identify the subjects for whom treatment is really beneficial.

Background and Purpose Stroke, disability, and dementia often coexist in elderly people. We assessed the prevalence and mutual association of these disorders in an elderly rural population. Methods We carried out a door-to-door survey on all subjects aged 65 years or over (n=1032) living in a rural community. To evaluate the associations between stroke and disability and between stroke and dementia, we compared stroke patients with all stroke-free subjects by means of two multiple logistic regression analyses. Subsequently, we performed a case-control analysis by comparing each stroke patient with two age- and sex-matched population control subjects. Results We identified 80 stroke patients. After the exclusion of five incident cases, the prevalence of stroke was 7.3% (95% confidence interval [CI], 5.7 to 8.9). Sixty-five percent of stroke survivors and 23% of stroke-free subjects were disabled (age- and sex-adjusted odds ratio [OR], 6.3; 95% CI, 3.7 to 10.9). Thirty percent of stroke survivors and 5.7% of stroke-free subjects were demented. The OR for dementia (stroke patients versus all stroke-free subjects) was 5.8 (95% CI, 3.1 to 10.8) and became 3.4 (95% CI, 1.5 to 8.0) in the case-control analysis. Conclusions In our population, the prevalence of stroke was higher than in previous studies. Stroke survivors were more disabled and more at risk for dementia than stroke-free subjects.

Puberty, either spontaneous, precocious or pharmacologically induced has profound effects on the physiology of the GH/IGF-I axis. Both spontaneous and stimulated GH secretion increase with puberty. The increase in spontaneous GH secretion is the result of increased GH pulse amplitude rather than frequency, and is probably an oestrogen-dependent effect. Parallel to the increase in GH secretion at puberty, circulating IGF-I and IGF binding protein-3 also increase. The pubertal increase in IGF-I correlates with stages of puberty as well as sex steroid levels. Circulating immunoreactive GHRH also increases with puberty, while circulating GH-binding protein levels are not affected by sexual maturation. Several data suggest an important role for the GH/IGF-I axis in the pubertal growth spurt. More recent data, however, have provided evidence of an important role for gonadal hormones in promoting adolescent growth independent of GH.

We studied terahertz current oscillations induced by a frequency-tunable radiation source in a AlGaAs/InGaAs/AlGaAs heterostructure field effect transistor channel. A planar antenna was integrated on-chip, and a substrate lens was used for broadband coupling of free-space radiation at 0.18-0.72 THz to the channel ends. Through spectral analysis of the detection signal, we identified two different mixing mechanisms: one related to channel current oscillations and the other to modulation of the gate-to-channel potential. Depending on gate bias and radiation frequency, the two mechanisms either compete or cooperate, leading to responsivity up to 300 V/W and noise equivalent power of 1 nW/Hz(0.5) (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4717464]

A computational method is presented for recovering 3-D shapes by exploiting multiple views of an object. The method provides a volumetric representation of the object starting from the occluding contours, i.e., the contours which separate the object image from the background. A detailed description of the geometrical transformations applied to build the volumetric representation of objects from multiple occluding contours of real images is reported. The only input parameters necessary are the orientation of the TV cameras used. The volumetric representation obtained is recognized by matching it with a library of models. Object recognition is performed in two steps. In the first step, some 3-D global structure parameters are used. If these are not sufficient to unambiguously recognize the object, in the second step the candidates chosen among the models are projected into the image planes of the TV cameras, and some 2-D features are used to perform the recognition, The models can be built either by means of a CAD technique or via the same method used to reconstruct the volumetric representation of the object.