We demonstrate an optical machine learning method in the terahertz domain, which allows the recognition of objects within a single measurement. As many materials are transparent in the terahertz ...spectral region, objects hidden within such materials can be identified. In contrast to typical object recognition methods, our method only requires a single pixel detector instead of a focal plane array. The core of the calculation is performed by a quantum cascade laser generated terahertz beam, which is spatially modulated at a near-infrared encoded silicon wafer. We show that this method is robust against displacements of the objects and noise. Additionally, the method is flexible and, due to the optically performed recognition task, inherently fast.
Background. In subjects with end-stage renal disease, a high body mass index (BMI) is inversely related to overall mortality, which has been coined reverse epidemiology phenomenon. This study sought ...to investigate this paradox as well as a possible risk modification by proteinuria on the relationship of BMI with earlier stages of chronic kidney disease (CKD) concerning cardiovascular mortality. Methods. We used the Vienna Health Screening Initiative, a longitudinal cohort study from 1990 to 2006, including 49 398 volunteers (49.9% women, age 20–89 years): n = 2487 showed mild CKD (proteinuria and GFR >60 ml/min/1.73 m2) and n = 392 showed moderate CKD (GFR = 30–59 ml/min/1.73 m2). The follow-up period was 5.5 ± 4.2 years; n = 148 cardiovascular deaths occurred. Exposure variables were BMI, glomerular filtration rate (GFR) and proteinuria. Cox regression models on cardiovascular mortality with adjustment for age, sex, log(cholesterol/HDL), uric acid, smoking, glucose, diabetes, mean blood pressure, hypertension and antihypertensive drug use were fitted. Results. The risk factor paradox is shown in moderate CKD (GFR = 45 ml/min/1.73 m2): hazard ratios (HR) of BMI contrasts decreased consistantly from 1.28 (95% CI 0.33–5.82) at BMI 20 kg/m2 versus 25 kg/m2 to 0.76 (95% CI 0.38–1.50) at BMI 30 kg/m2 versus 25 kg/m2 and to 0.58 (95% CI 0.13–2.64) at BMI 35 kg/m2 versus 25 kg/m2, thus showing an inverse relationship compared to mild CKD/healthy participants. Examining proteinuria as an effect modifier in this context showed that in moderate CKD (contrast: proteinuria versus no proteinuria) HR decreased more profoundly from 9.43 (95% CI 2.66–27.40) at BMI 25 kg/m2 to 3.74 (95% CI 0.93–15.70) at BMI 30 kg/m2 and to 1.95 (95% CI 0.37–22.30) at BMI 35 kg/m2, and conversely in non-proteinuric subjects, hazards for cardiovascular mortality increased in underweight as well as in overweight/obese subjects in a U-shaped manner. Conclusions. Our results suggest that obese subjects with proteinuric CKD may not be counselled for weight reduction since a higher BMI was associated with a remarkably reduced risk of death.
The proton transfer reaction HOCO
+
+CO → HCO
+
/HOC
+
has been studied using crossed-beam velocity map imaging. Angular and energy differential cross sections were obtained for collision energies ...from 0.3 to 2.3 eV. Scattering in forward direction together with a prominent scattering angle-dependent internal excitation is found at all collision energies. The exothermic HCO
+
product appears to be very dominant even at energies above the energy threshold for the formation of metastable HOC
+
ion. To determine the HOC
+
contribution for different angular ranges, a model has been developed. We obtain an upper limit for the HOC
+
product isomer fraction of <2%. In theoretical calculations, we find the CO
2
-catalysed isomerisation channel to be energetically accessible. However, it may not have a strong impact on the isomer ratio. Chemical dynamics simulations are needed to shed more light on this question.
•Determination of the effective refractive index for metasurfaces.•Frequency prediction for accessible higher order modes.•Frequency control due to the modification of the dielectric ...environment.•Linewidth is stable against modifications of the dielectric environment.•Independent control of frequency position and linewidth.
We present an experimental time-domain-spectroscopy study of the plasmonic resonance behavior of metamaterial surfaces in the terahertz regime. We determine the effective refractive index of the dielectric environment and its influence on meta-atoms built of connected dipoles. Our findings show that an analytical calculation of their resonance frequencies including higher order modes is possible and yield a method of frequency response prediction for complex meta-atom geometries. By modifying the dielectric environment, we introduce a way to control independently frequency and linewidth of the localized plasmons. Unlike the resonance frequency, which is strongly affected by a modification, the losses are robust against changes of the surrounding media. It is shown that the interaction channel between the single elements is dominantly mediated by the substrate. Our experimental findings can therefore contribute to the future conception of actively controllable complex photonic device structures.
Acute renal failure (ARF) as well as chronic kidney disease (CKD) are currently categorized according to serum creatinine concentrations. Serum creatinine, however, has shortcomings because of its ...low predictive values. The need for novel markers for the early diagnosis and prognosis of renal diseases is imminent, particularly for markers reflecting intrinsic organ injury in stages when glomerular filtration is not impaired. This review summarizes protein markers discussed in the context of ARF as well as CKD, and provides an overview on currently available discovery results following ‘omics’ techniques. The identified set of candidate marker proteins is discussed in their cellular and functional context. The systematic review of proteomics and genomics studies revealed 56 genes to be associated with acute or chronic kidney disease. Context analysis, i.e. correlation of biological processes and molecular functions of reported kidney markers, revealed that 15 genes on the candidate list were assigned to the most significant ontology groups: immunity and defence. Other significantly enriched groups were cell communication (14 genes), signal transduction (22 genes) and apoptosis (seven genes). Among 24 candidate protein markers, nine proteins were also identified by gene expression studies. Next generation candidate marker proteins with improved diagnostic and prognostic values for kidney diseases will be derived from whole genome scans and protemics approaches. Prospective validation still remains elusive for all proposed candidates.
Quantum cascade lasers (QCLs) have been realized in several different material systems. In the mid‐infrared, active regions are predominantly based on In0.53Ga0.47As and InAs as quantum well ...material. Market‐ready devices routinely provide continuous‐wave operation at room temperature. For their THz counterparts, the situation is less clear. The most common material system for THz QCLs is the inherently lattice‐matched combination of GaAs with Al0.15Ga0.85As barriers. Yet, these devices still only reach a maximum operating temperature of 200 K with a lack of progress within the past years. Based on the identification of key parameters, this work reviews material systems for quantum cascade lasers with an emphasis on material and growth‐related aspects and the goal to identify promising candidates for future device generations. Similar active regions realized in different material systems allow to estimate the gain per unit thickness, as well as total growth times and relative thickness errors.
This work evaluates different material systems for THz quantum cascade laser active regions. Different combinations of quantum well and barrier materials are discussed with respect to growth and design‐related issues including practical aspects like a thickness error estimation. Experimental data from established materials furthermore allow to gauge the suitability of novel candidate materials.
Patients with “hepatic” bone disease exhibit increased fracture incidence. The effects on bone material properties, their changes due to orthotopic liver transplantation (OLT), as well as ...zolendronate (ZOL) treatment have not yet been investigated. We studied bone mineralization density distribution (BMDD) in paired transiliacal biopsies (at and 6 months after OLT) from patients (control CON
n
= 18, treatment group ZOL
n
= 21, the latter treated with i.v. ZOL at doses of 4 mg/month) for how bone at the material level was affected by the “hepatic” disease in general, as well as by OLT and ZOL in particular. (1) BMDD parameters at baseline reflected disturbed bone matrix mineralization in “hepatic” bone disease combined with low turnover. Trabecular bone displayed a decrease in mean and most frequent calcium concentration (Ca
MEAN
−2.9% and Ca
PEAK
−2.8%, respectively; both
P
< 0.001), increased heterogeneity of mineralization (Ca
WIDTH
+12.2%,
P
= 0.01), and increased percentage of bone areas with low mineralization (Ca
LOW
+32.4%,
P
= 0.02) compared to normal; however, there were no differences compared to cortical bone. (2) Six months after OLT, ZOL-treated trabecular bone displayed reduced Ca
LOW
(−32.0%,
P
= 0.047), cortical bone increased Ca
MEAN
(+4.2%,
P
= 0.009), increased Ca
PEAK
(+3.3%,
P
= 0.040), and decreased Ca
LOW
(−55.7,
P
= 0.038) compared to CON and increased Ca
MEAN
compared to baseline (+1.9,
P
= 0.032) without any signs of hyper- or defective mineralization. These changes as consequence of the antiresorptive action of ZOL visible already after 6 months result in beneficial effects on bone matrix mineralization, likely contributing to the significant decrease in fracture incidence observed in these patients 2 years post transplantation.
We demonstrate a convenient and fast method to measure the spectrally resolved far-fields of multimode terahertz quantum cascade lasers by combining a microbolometer focal plane array with an FTIR ...spectrometer. Far-fields of fundamental TM0 and higher lateral order TM1 modes of multimode Fabry-Pérot type lasers have been distinguished, which very well fit to the results obtained by a 3D finite-element simulation. Furthermore, multimode random laser cavities have been investigated, analyzing the contribution of each single laser mode to the total far-field. The presented method is thus an important tool to gain in-depth knowledge of the emission properties of multimode laser cavities at terahertz frequencies, which become increasingly important for future sensing applications.
The article
Hearing preservation in children with electric-acoustic stimulation after cochlear implantation
—
Outcome after electrode insertion with minimal insertion trauma
, written by T. Rader, ...A. Bohnert, C. Matthias, D. Koutsimpelas, M‑A. Kainz, S. Strieth was originally published electronically
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