Link Budget Analysis for Terahertz Fixed Wireless Links Schneider, Thomas; Wiatrek, A.; Preussler, S. ...
IEEE transactions on terahertz science and technology,
2012-March, 2012-03-00, Volume:
2, Issue:
2
Journal Article
Peer reviewed
Due to the broad bandwidths, terahertz (THz)-waves offer the possibility for wireless transmission of high data rates. Especially, broadband wireless access over short ranges and fixed wireless links ...based on THz-waves are very promising. They can be incorporated as a bridge for optical networks or an alternative for the connection of wireless stations in difficult environments, to transmit next generation HDTV signals or for the broadband connection of servers in a data center, for instance. The frequency range between 300 and 900 GHz is very promising for these applications since the possible bandwidth is very high and first electronic circuits will become available on the market soon. However, contrary to wireless links in the lower GHz-bands, the free-space path-loss is quite high and the attenuation due to molecules in the air or water droplets can significantly decrease the transmittable data rates in this frequency range. Here the basic properties of THz-waves will be investigated and the maximum achievable data rates for fixed wireless THz-links will be derived. In order to keep the considerations as general as possible, the derivations are based on simple assumptions and equations. Additionally, conclusions for the applicability of THz-waves for fixed wireless links with distances up to 1 km will be given and the special requirements for these systems will be discussed. As we will show, high data rates can only be transmitted via these links if transmitter and receiver antennas with very high gains are used. This requires an adaptive control of mechanical fluctuations.
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.
Australopithecine butchers Braun, David R.
Nature (London),
08/2010, Volume:
466, Issue:
7308
Journal Article
Peer reviewed
Open access
Other marks that represent pounding on the bone surfaces suggest that these hominins (members of the human lin eage) also took an interest in the nutrient-rich bone marrow. ... there has been no ...direct evidence that meat and marrow formed part of the diet of hominins at this early age.
The microstructure of a friction stir-welded Al–6.0Cu–0.75Mg–0.65Ag (wt.%) alloy in the peak-aged T6 temper was characterized by transmission electron microscopy. Strengthening precipitates found in ...the base alloys dissolved in the weld nugget, while those in the heat-affected zone coarsened considerably, causing softening inside the weld region. Precipitates of the Ω (Al2Cu) phase, being the main strengthening phase in base material, grew up to 200–300nm in the heat-affected zone, but their density decreased. They co-existed with Θ′ (Al2Cu), S′ (Al2CuMg), Θ (Al2Cu) and σ (Al5Cu6Mg2) phases. The density of the Θ′ and S′ phases as well as their sizes increased compared to the base material. The high-resolution observation allowed to compare the morphology of the Ω phase plates in the heat-affected zone and in the base material.
Patients' knowledge of anaesthetists' qualifications and roles remains inaccurate despite the efforts of professional bodies worldwide. However, patients have not been surveyed on this subject in ...Australia for more than 20 years. We therefore surveyed 200 patients attending the pre-admission clinic prior to elective non-cardiothoracic surgery in an Australian teaching hospital to determine current knowledge. Most (90.5%) patients stated that anaesthetists are medically qualified and 83.5% stated that they are medical specialists. Younger age, an English-speaking background and previous experience with surgery predicted knowledge of anaesthetists' qualifications. Most patients believed that anaesthetists work in the operating theatre and are continually present during surgery, but few recognised their leading role in the care of patients during surgery or their other roles outside the operating theatre. Increased efforts are required to inform patients about the roles of anaesthetists in their care.
Recent sequencing and assembly of the genome for the fungal pathogen Candida albicans used simple automated procedures for the identification of putative genes. We have reviewed the entire assembly, ...both by hand and with additional bioinformatic resources, to accurately map and describe 6,354 genes and to identify 246 genes whose original database entries contained sequencing errors (or possibly mutations) that affect their reading frame. Comparison with other fungal genomes permitted the identification of numerous fungus-specific genes that might be targeted for antifungal therapy. We also observed that, compared to other fungi, the protein-coding sequences in the C. albicans genome are especially rich in short sequence repeats. Finally, our improved annotation permitted a detailed analysis of several multigene families, and comparative genomic studies showed that C. albicans has a far greater catabolic range, encoding respiratory Complex 1, several novel oxidoreductases and ketone body degrading enzymes, malonyl-CoA and enoyl-CoA carriers, several novel amino acid degrading enzymes, a variety of secreted catabolic lipases and proteases, and numerous transporters to assimilate the resulting nutrients. The results of these efforts will ensure that the Candida research community has uniform and comprehensive genomic information for medical research as well as for future diagnostic and therapeutic applications.
REPLY TO SAHLE AND GOSSA Braun, David R.; Aldeias, Vera; Archer, Will ...
Proceedings of the National Academy of Sciences - PNAS,
10/2019, Volume:
116, Issue:
41
Journal Article
Peer reviewed
Open access
Sahle and Gossa (1) identify 2 components of our paper with which they disagree. Their concerns are based on misunderstandings of our paleomagnetic data and the published details of the Bokol Dora 1 ...(BD 1) artifact assemblage.
A new perspective on GCRT J1745-3009 Spreeuw, H.; Scheers, B.; Braun, R. ...
Astronomy and astrophysics (Berlin),
08/2009, Volume:
502, Issue:
2
Journal Article
Peer reviewed
Open access
Context. Reports on a transient source about 1.25° south of the Galactic Centre motivated these follow-up observations with the WSRT and the reinvestigation of archival VLA data. The source ...GCRT J1745-3009 was detected during a 2002 Galactic Centre monitoring programme with the VLA at 92 cm by five powerful 10-min bursts with a 77-min recurrence while apparently lacking any interburst emission. Aims. The WSRT observations were performed and archival VLA data reduced to detect GCRT J1745-3009 again at different epochs and frequencies, to constrain its distance, and to determine its nature. We attempted to extract a more accurate lightcurve from the discovery dataset of GCRT J1745-3009 to rule out some of the models that have been suggested. We also investigated the transient behaviour of a nearby source. Methods. The WSRT data were taken in the “maxi-short” configuration, using 10 s integrations, on 2005 March 24 at 92 cm and on 2005 May 14/15 at 21 cm. Five of the six VLA observations we reduced are the oldest of this field in this band. Results. GCRT J1745-3009 was not redetected. With the WSRT we reached an rms sensitivity of 0.21 mJy ${\rm beam^{-1}}$ at 21 cm and 3.7 mJy ${\rm beam^{-1}}$ at 92 cm. Reanalysis of the discovery observation data resulted in a more accurate and more complete lightcurve. The five bursts appear to have the same shape: a steep rise, a more gradual brightening, and a steep decay. We found variations in burst duration of order ${\simeq}3\%$. We improved the accuracy of the recurrence period of the bursts by an order of magnitude: 77.012 ± 0.021 min. We found no evidence of aperiodicity. We derived a very steep spectral index: $\alpha=-6.5$ ± 3.4. We improved the $5\sigma$ upper limits for interburst emission and fractional circular polarisation to 31 mJy ${\rm beam^{-1}}$ and $8\%$, respectively. Any transient behaviour of a nearby source could not be established. Conclusions. Models that predict symmetric bursts can be ruled out, but rotating systems are favoured, because their periodicity is precise. Scattering constraints imply that GCRT J1745-3009 cannot be located far beyond the GC. If this source is an incoherent emitter and not moving at a relativistic velocity, it must be closer than 14 pc.
A computational model for semiconductor crystal growth on a partially masked substrate under simplified liquid phase electroepitaxy conditions is developed. The model assumes isothermal diffusional ...growth, which is enhanced by applied DC current through crystal-solution interface. A finite-difference, front-tracking method is used to numerically evolve the interface. Computed examples show strong influence of the electromigration on growth rates in vertical and lateral directions and the dependence of growth on electrical resistance of mask material, and on the wetting contact angle.
Fibroblast growth factor 21 (FGF21) ameliorates steatohepatitis but is increased in humans with fatty liver, potentially due to compensatory mechanisms and/or FGF21 resistance. Further, animal models ...suggest that GH increases serum FGF21. Tesamorelin, a growth hormone releasing hormone agonist, reduces liver fat in HIV-infected individuals. The objectives of this study were to investigate changes in FGF21 during tesamorelin treatment, to elucide the interplay between FGF21, GH augmentation, and liver fat reduction in humans.
50 HIV-infected men and women with increased abdominal adiposity participated in this randomized, placebo-controlled trial of tesamorelin, 2mg vs. identical placebo daily for six months. Fasting laboratory measures, liver fat by 1H-magnetic resonance spectroscopy, and visceral adipose tissue (VAT) by computed tomography were obtained. Euglycemic hyperinsulinemic clamp was performed in a randomly selected subset.
At baseline, serum log10 FGF21 was significantly associated with log10 liver fat (r=0.32, p=0.03). Log10 FGF21 tended to decrease in the tesamorelin group compared to placebo (p=0.06). Among the entire cohort, reductions in FGF21 were significantly associated with reductions in liver fat (ρ=0.41, p=0.01), log10 gamma glutamyl tran speptidase (GGT, r=0.40, p=0.009), and FIB4 index (r=0.37, p=0.02).
In HIV-infected individuals, FGF21 is significantly positively associated with liver fat. FGF21 decreases in association with reductions in liver fat, GGT, and FIB4, suggesting that FGF21 is upregulated in the context of steatosis and steatohepatitis and is reduced when these conditions improve. Moreover, these data suggest that tesamorelin improves liver fat via pathways other than increasing serum FGF21.
clinicaltrials.govNCT01263717.
•FGF21 is positively associated with liver fat content in HIV-infected individuals•Reductions in liver fat achieved with tesamorelin are significantly associated with reductions in FGF21, GGT, and FIB4.•These data suggest that FGF21 is upregulated with increased liver fat, and tesamorelin's effect is not mediated via FGF21.
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