Isospectrality of spherical MHD dynamo operators: pseudo-Hermiticity and a no-go theorem

The isospectrality problem is studied for the operator of the spherical hydromagnetic alpha^2-dynamo. It is shown that this operator is formally pseudo-Hermitian (J-symmetric) and lives in a Krein space. Based on the J-symmetry, an operator intertwining Ansatz with first-order differential intertwining operators is tested for its compatibility with the structure of the alpha^2-dynamo operator matrix. An intrinsic structural inconsistency is obtained in the set of associated matrix Riccati equations. This inconsistency is interpreted as a no-go theorem which forbids the construction of isospectral alpha^2-dynamo operator classes with the help of first-order differential intertwining operators.Comment: 13 pages, LaTeX2e, improved references, to appear in J. Math. Phy

Bacteriophage T₄ induced modification of valyl-tRNA synthetase in Escherichia coli. : an analysis of the kinetics and regulation

Digitized by Kansas Correctional Industrie

Effects of nocturnal air and rail traffic noise on sleep

Undisturbed and sufficiently long sleep is a prerequisite for a healthy life as well as for the prevention of fatigue-induced accidents. Especially the increasing air and freight rail traffic is more and more shifted to shoulder and night-time hours due to missing capacity and infrastructure during daytime. Thus, the sleep of residents near airports or railway tracks is increasingly affected by traffic noise. Only very few main airports, such as Frankfurt (Germany), implemented a night flight ban in order to countervail this trend. Since 1999 the Institute of Aerospace Medicine of the German Aerospace Center (DLR) has investigated these night time noise effects in several field studies in which the sound pressure levels L AS and L AF and sound files were continuously measured with class one sound level meters at the sleeper's ear. Sleep structure was recorded with polysomnography (simultaneous measurement of brain waves, eye movements, and muscle tone), the gold-standard to quantify sleep objectively. The results on sleep quality and additional awakening reactions due to traffic noise from former studies performed at Cologne/Bonn airport (high night time traffic) and a busy railway track in the Rhine valley (high night time freight traffic) are compared with the results of the recently completed NORAH (Noise-Related Annoyance, Cognition, and Health) study at Frankfurt airport. In the latter study data were collected both before as well as after the implementation of a ban of night flights between 11 p.m. and 5 a.m.. Sound exposure distributions, average sound levels and sound level rise time distributions at the sleepers' ear are presented for all three studies

A comparison of the effects of night time air traffic noise on sleep at Cologne/Bonn and Frankfurt Airport after the night flight ban

In the STRAIN study (2001/2002) the German Aerospace Center (DLR) measured the sleep of 64 residents (19-61 years) around Cologne/Bonn airport for 9 consecutive nights each with polysomnography. Cologne/Bonn airport has no night time restrictions for chapter 3 airplanes and is one of the busiest airports in Germany during the night. Frankfurt is the airport with the highest traffic volume in Germany. A night flight ban (11 p.m.-5 a.m.) was implemented in October 2011. Traffic density during shoulder hours is high. DLR examined 83 Frankfurt airport residents (18-77 years) with polysomnography as part of the NORAH study in 2012. In both studies sound pressure level (SPL) and noise events were recorded with microphones near the sleeper's ear. Participants filled out questionnaires each morning. The analysis shows that aircraft noise associated awakening probabilities were 3.8-7.5% higher for maximum indoor levels from 30-70 dB(A) at Cologne/Bonn Airport whereas night time aircraft noise annoyance was higher in Frankfurt. The results of both studies are compared, and limitations of the comparisons are discussed

Cross-country comparison of aircraft noise-induced sleep disturbance

To inform policy, exposure-response relationships for aircraft noise-induced sleep disturbance are needed. Due to different nighttime airport operational patterns it has been unknown whether results from individual studies can be applied to other airports. In addition, there may be inter-cultural differences that affect an individual's sensitivity to awakening. To examine whether there are crosscountry differences in aircraft noise-induced awakenings, results from 3 studies that obtained objective sleep and noise measurements were compared. Two of the studies were conducted in Germany and include the STRAIN study conducted near Cologne/Bonn airport (N=64) and data from three years of the NORAH study conducted near Frankfurt airport (year 1 N=49; year 2 N=83; year 3 N=187). The third study was conducted in the United States near Philadelphia International airport (N=37). Awakenings were identified based on ECG and actigraphy measurements using an automatic algorithm, enabling consistency in scoring across the three studies. Models relating awakenings to the indoor maximum noise level of single aircraft events were derived. Similarities and differences in the regressions of the 3 studies are discussed

Synthesis and Reactions of the Homoleptic Chromium(II) Bis-amide [Ph₂PN(ⁱPr)P(Ph)N(ⁱPr)−]₂Cr with Relevance to a Selective Catalytic Ethene Trimerization System to 1-Hexene

New organometallic compounds were obtained on the basis of the aminodiphosphinoamine ligand Ph₂PN­(ⁱPr)­P­(Ph)­N­(ⁱPr)-H (<b>1</b>), which is relevant for the selective ethene trimerization system consisting of ligand <b>1</b>, CrCl₃(THF)₃, and Et₃Al. This catalytic system produces 1-hexene in more than 90% yield and high purity. Here, we report a more efficient, high-yield synthesis of the recently published homoleptic magnesium complex [Ph₂PN­(ⁱPr)­P­(Ph)­N­(ⁱPr)−]₂Mg (<b>2</b>) by reaction of <i>n</i>-butylethylmagnesium and <b>1</b> in Et₂O. Compound <b>2</b> can be used as a reagent to transfer the amide moiety [Ph₂PN­(ⁱPr)­P­(Ph)­N­(ⁱPr)−] effectively to a chromium or aluminum center. <i>In situ</i> synthesis of the magnesium amide <b>2</b> followed by addition of CrCl₂(THF)₂ results in the formation of the homoleptic chromium­(II)­bis-amide [Ph₂PN­(ⁱPr)­P­(Ph)­N­(ⁱPr)−]₂Cr (<b>3</b>) by transmetalation. The structure of chromium compound <b>3</b> is in some aspects similar to that of the corresponding homoleptic magnesium complex <b>2</b>. Reacting <b>2</b> with ethylaluminum dichloride results in the formation of the respective aluminum amide [Ph₂PN­(ⁱPr)­P­(Ph)­N­(ⁱPr)−]­[AlEtCl] (<b>4</b>), for which the direct synthesis of <b>1</b> with diethylaluminum chloride was unsuccessful. Additionally, we investigated compound <b>3</b> with potentially interesting activators such as Et₂Zn, Et₃Al, and Et₃B to obtain more information about the catalytic properties of these systems

Synthesis and Reactions of the Homoleptic Chromium(II) Bis-amide [Ph₂PN(ⁱPr)P(Ph)N(ⁱPr)−]₂Cr with Relevance to a Selective Catalytic Ethene Trimerization System to 1-Hexene

New organometallic compounds were obtained on the basis of the aminodiphosphinoamine ligand Ph₂PN­(ⁱPr)­P­(Ph)­N­(ⁱPr)-H (<b>1</b>), which is relevant for the selective ethene trimerization system consisting of ligand <b>1</b>, CrCl₃(THF)₃, and Et₃Al. This catalytic system produces 1-hexene in more than 90% yield and high purity. Here, we report a more efficient, high-yield synthesis of the recently published homoleptic magnesium complex [Ph₂PN­(ⁱPr)­P­(Ph)­N­(ⁱPr)−]₂Mg (<b>2</b>) by reaction of <i>n</i>-butylethylmagnesium and <b>1</b> in Et₂O. Compound <b>2</b> can be used as a reagent to transfer the amide moiety [Ph₂PN­(ⁱPr)­P­(Ph)­N­(ⁱPr)−] effectively to a chromium or aluminum center. <i>In situ</i> synthesis of the magnesium amide <b>2</b> followed by addition of CrCl₂(THF)₂ results in the formation of the homoleptic chromium­(II)­bis-amide [Ph₂PN­(ⁱPr)­P­(Ph)­N­(ⁱPr)−]₂Cr (<b>3</b>) by transmetalation. The structure of chromium compound <b>3</b> is in some aspects similar to that of the corresponding homoleptic magnesium complex <b>2</b>. Reacting <b>2</b> with ethylaluminum dichloride results in the formation of the respective aluminum amide [Ph₂PN­(ⁱPr)­P­(Ph)­N­(ⁱPr)−]­[AlEtCl] (<b>4</b>), for which the direct synthesis of <b>1</b> with diethylaluminum chloride was unsuccessful. Additionally, we investigated compound <b>3</b> with potentially interesting activators such as Et₂Zn, Et₃Al, and Et₃B to obtain more information about the catalytic properties of these systems

Liver Imaging with a Novel Hepatitis B Surface Protein Derived SPECT-Tracer

Diagnostic imaging of the liver by ultrasound, computed tomography (CT) and magnetic resonance tomography (MRT) is generally limited to the visualization of the morphology. In order to exploit the intriguing liver tropism of the human hepatitis B virus (HBV) for molecular imaging of the liver, peptidic tracers derived from the HBV large envelope protein (L) were studied. An N-terminally stearoylated tracer comprising amino acids 2–48 of the PreS1-domain of the L protein was synthesized by solid phase peptide synthesis. Mercaptoacetyltriglycerin (MAG3) was linked to this peptide to enable ^99mTc labeling. Biodistribution studies in mice showed an excellent liver accumulation of this novel class of radiotracer with 84%, 84%, 65%, and 16% of the injected dose in the liver after 10 min, 1 h, 4 h, and 24 h, respectively. Imaging studies on a gamma camera showed a clear visualization of the liver already 10 min post intravenous injection. These studies confirmed the exclusive accumulation of the tracer in the liver with negligible background in other organs. Owing to a significant biliary clearance rate of the ^99mTc bound via a linker, the tracer enabled imaging of the bile ducts starting 30 min after injection. Analysis of the route of excretion revealed complete clearance within 24 h post injection. Clearance was predominantly via renal secretion. In conclusion, the novel class of tracers shows excellent pharmacokinetic, biodistribution, and clearance kinetics. It provides unique biological information different from the current imaging modalities. Its primary application is likely to be the evaluation of liver cancer patients. Specific indications may include tumor staging, the differentiation of malignant versus benign hepatic lesions, and liver tumors of nonhepatocellular origin