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K Hansen

Publications and source records attributed to K Hansen.

At least 37 records · Page 2Linked to original sources
PubMed2003

Compton scattering from the deuteron and extracted neutron polarizabilities.

Differential cross sections for Compton scattering from the deuteron were measured at MAX-Lab for incident photon energies of 55 and 66 MeV at nominal laboratory angles of 45 degrees, 125 degrees, and 135 degrees. Tagged photons were scattered from liquid deuterium and detected in three NaI spectrometers. By comparing the data with theoretical calculations in the framework of a one-boson-exchange potential model, the sum and the difference of the isospin-averaged nucleon polarizabilities, alpha(N)+beta(N)=17.4+/-3.7 and alpha(N)-beta(N)=6.4+/-2.4 (in units of 10(-4) fm(3)), have been determined. By combining the latter with the global-averaged value for alpha(p)-beta(p) and using the predictions of the Baldin sum rule for the sum of the nucleon polarizabilities, we have obtained values for the neutron electric and magnetic polarizabilities of alpha(n)=8.8+/-2.4(total)+/-3.0(model) and beta(n)=6.5-/+2.4(total)-/+3.0(model), respectively.

Journal Article↗
PubMed2003

A pharmacoeconomic evaluation of escitalopram, a new selective serotonin reuptake inhibitor. Comparison of cost-effectiveness between escitalopram, citalopram, fluoxetine, and venlafaxine for the treatment of depression in Norway.

This study compared the cost-effectiveness of escitalopram to that of citalopram,fluoxetine, and venlafaxine in the treatment of depression in Norway. A two-path decision analytic model with a 6-month horizon was used. Patients start at the primary path and are referred to specialist care in the secondary care path. Model inputs included drug-specific probabilities from comparative trial data, literature, and a panel of experts. The main outcome measure is success (remission), and costs of treatment (total and drug costs). Treatment with escitalopram yielded lower expected cost and greater effectiveness than citalopram, fluoxetine, and venlafaxine. The expected success rate was 64.2% with escitalopram,58.7% with citalopram, 58.7% with fluoxetine, and 62.1% with venlafaxine. Average expected total costs per patient were similar with escitalopram (19,661 Norwegian crowns) and venlafaxine (20,989) and somewhat higher with citalopram (22,379) and fluoxetine (22,558). Budgetary impact estimates a decrease in total health care budget of 72 million crowns. Escitalopram is therefore the most cost-effective alternative and its use would significantly reduce health care costs for the treatment of depression in Norway.

Journal Article↗
PubMed2002

Current-voltage curves of atomic-sized transition metal contacts: an explanation of why Au is Ohmic and Pt is not.

We present an experimental study of current-voltage (I-V) curves on atomic-sized Au and Pt contacts formed under cryogenic vacuum (4.2 K). Whereas I-V curves for Au are almost Ohmic, the conductance G=I/V for Pt decreases with increasing voltage, resulting in distinct nonlinear I-V behavior. The experimental results are compared with first principles density functional theory calculations for Au and Pt, and good agreement is found. The difference in conductance properties for Pt vs Au can be explained by the underlying electron valence structure: Pt has an open d shell while Au has not.

Journal Article↗
PubMed2002

Helicity amplitudes A1/2 and A3/2 for the D13(1520) resonance obtained from the gamma-->p-->-->ppi(0) Reaction.

The helicity dependence of the gamma-->p-->-->ppi(0) reaction has been measured for the first time in the photon-energy range from 550 to 790 MeV. The experiment, performed at the Mainz microtron MAMI, used a 4pi-detector system, a circularly polarized, tagged photon beam, and a longitudinally polarized frozen-spin target. These data are predominantly sensitive to the D13(1520) resonance and are used to determine its helicity amplitudes.

Journal Article↗
PubMed2002

Dependence of morphology on agitation intensity in fed-batch cultures of Aspergillus oryzae and its implications for recombinant protein production.

We previously reported that, although agitation conditions strongly affected mycelial morphology, such changes did not lead to different levels of recombinant protein production in chemostat cultures of Aspergillus oryzae (Amanullah et al., 1999). To extend this finding to another set of operating conditions, fed-batch fermentations of A. oryzae were conducted at biomass concentrations up to 34 g dry cell weight/L and three agitation speeds (525, 675, and 825 rpm) to give specific power inputs between 1 and 5 kWm(-3). Gas blending was used to control the dissolved oxygen level at 50% of air saturation except at the lowest speed where it fell below 40% after 60-65 h. The effects of agitation intensity on growth, mycelial morphology, hyphal tip activity, and recombinant protein (amyloglucosidase) production in fed-batch cultures were investigated. In the batch phase of the fermentations, biomass concentration, and AMG secretion increased with increasing agitation intensity. If in a run, dissolved oxygen fell below approximately 40% because of inadequate oxygen transfer associated with enhanced viscosity, AMG production ceased. As with the chemostat cultures, even though mycelial morphology was significantly affected by changes in agitation intensity, enzyme titers (AGU/L) under conditions of substrate limited growth and controlled dissolved oxygen of >50% did not follow these changes. Although the measurement of active tips within mycelial clumps was not considered, a dependency of the specific AMG productivity (AGU/g biomass/h) on the percentage of extending tips was found, suggesting that protein secretion may be a bottle-neck in this strain during fed-batch fermentations.

Aspergillus oryzae↗
PubMed2002

Pyogranulomatous myocarditis due to Staphylococcus aureus septicaemia in two harbour porpoises (Phocoena phocoena).

Staphylococcus aureus septicaemia was diagnosed in a dead, stranded harbour porpoise from the German Baltic Sea and in a live harbour porpoise by-caught in inner Danish waters and taken into captivity. Lesions included pyogranulomatous myocarditis, necrotising suppurative bronchopneumonia, pyelonephritis, osteomyelitis and leptomeningitis, and abscesses in lymph nodes and skeletal muscles. The captive animal had fibrinous suppurative epicarditis and pyogranulomatous myocarditis with abscesses. In both animals the organism was suspected to have entered through skin lesions or via the respiratory tract.

Animals↗
PubMed2002

A pharmacoeconomic evaluation of zuclopenthixol compared with haloperidol and risperidone in the treatment of schizophrenia.

Zuclopenthixol and haloperidol are antipsychotic medications displaying different galenic forms, while risperidone is available on the market only in tablet form. The depot form presents advantages; the duration of action allows 3-4 weeks between administrations. A meta-analysis showed that zuclopenthixol patients had a higher response rate than haloperidol. A Markov model was developed to estimate the cost-effectiveness of the three antipsychotics in schizophrenia over a 5-year period. Model parameter estimates were based on a meta-analysis and literature. The viewpoint was that of the French National Health Insurance. When compared to haloperidol and risperidone, zuclopenthixol patients had additional 4 and 7 months without relapse correspondingly over a 5-year period. The estimated 5-year medical cost associated with zuclopenthixol was 800 and 1100 euros less than haloperidol and risperidone, respectively, per patient. Sensitivity analyses indicated that the results were robust to changes in key variables. The model indicates that the zuclopenthixol treatment strategy dominates haloperidol and risperidone.

Journal Article↗
PubMed2001

Observation of a 1/t decay law for hot clusters and molecules in a storage ring.

The exponential law is valid both for decay from a single quantum state into a continuum and for an ensemble maintained in thermal equilibrium. For statistical decay of an ensemble of isolated systems with a broad energy distribution, the exponential decay is replaced by a 1/t distribution. We present confirmation of this decay law by experiments with cluster anions in a small electrostatic storage ring. Deviations from the 1/t law for such an ensemble give important information on the dynamics of the systems. As examples, we present measurements revealing strong radiative cooling of anions of both metal clusters and fullerenes.

Journal Article↗
PubMed2001

Model-free determination of dissociation energies of polyatomic systems.

We describe and apply a new procedure that allows a direct determination of dissociation energies of polyatomic systems (clusters, fullerenes, polymers, and other molecules) without any modeling of the systems under investigation. As an example, we have determined the dissociation energies of a series of gold clusters Au(+)n. A comparison with values obtained from statistical models of unimolecular dissociation shows that these models significantly fail to describe the data. In contrast, the new method yields values which are an order of magnitude more accurate, thus allowing one to experimentally set benchmarks for any theory which attempts to describe activated processes.

Journal Article↗
PubMed2001

Origin of nanomechanical cantilever motion generated from biomolecular interactions.

Generation of nanomechanical cantilever motion from biomolecular interactions can have wide applications, ranging from high-throughput biomolecular detection to bioactuation. Although it has been suggested that such motion is caused by changes in surface stress of a cantilever beam, the origin of the surface-stress change has so far not been elucidated. By using DNA hybridization experiments, we show that the origin of motion lies in the interplay between changes in configurational entropy and intermolecular energetics induced by specific biomolecular interactions. By controlling entropy change during DNA hybridization, the direction of cantilever motion can be manipulated. These thermodynamic principles were also used to explain the origin of motion generated from protein-ligand binding.

DNA, Single-Stranded↗
PubMed2001

Phosphorylation-dependent and -independent functions of p130 cooperate to evoke a sustained G1 block.

The retinoblastoma (pRb)-related p130 pocket protein is a regulator of cell growth and differentiation, and a candidate tumour suppressor. Both pRb and p130 operate through interactions with cellular proteins, including the E2F transcription factors. While such interactions are controlled by phosphorylation of multiple sites of pRb, regulation of p130 remains poorly understood. We now identify 22 in vivo phosphorylation sites of p130, targeted by diverse kinases, and present evidence for three cyclin-dependent kinase 4(6) [Cdk4(6)] specific phosphorylations, which appear critical for controlling the growth-restraining activity of p130. When expressed in U2OS cells, the phosphorylation-deficient mutant p130(Delta)(CDK4), in which the Cdk4 specific sites were mutated to alanine residues, imposed a more sustained G1 arrest than a constitutively active pRb(Delta)(CDK), known to repress all cellular E2F activity. Experiments using p130(Delta)(Cdk4) and another phosphorylation-deficient mutant, p130(PM19A), with 19 phosphorylation sites mutated, revealed that the p130-imposed G1 block reflects cooperative growth-suppressive effects of phosphorylation-regulated E2F binding and phosphorylation-independent sequestration of cyclin E(A)-Cdk2 through the N-terminal cyclin binding motif of p130.

Binding Sites↗
PubMed2001

Hsal 1 is related to kidney and gonad development and is expressed in Wilms tumor.

Townes-Brocks syndrome (TBS) is a human genetic disorder with features including urogenital, limb, anal and cardiac malformations associated with mutations of the TBS gene, Hsal 1. To begin to understand the role of the Hsal 1 protein (p140) in both normal development and disease pathogenesis, both message and protein expression were evaluated in specific tissues associated with TBS. DNA sequence information for Hsal 1 predicts that this homeotic, Drosophila homologue (Sal) encodes a zinc-finger protein consistent with a transcription factor. mRNA for Hsal 1 was highly expressed in fetal kidney and brain, with detectable production in thymus and heart. p140 was found in fetal ureteric bud, fetal and postnatal renal tubular epithelium, and renal blastema. In the 14-week fetal testis, the Hsal 1 protein was specifically expressed in the testosterone producing Leydig cells while in adult gonads Hsal 1 was also found in both Leydig and Sertoli cells, spermatogonia of the testis, and granulosa cells of the ovary. Evaluation of Wilms tumor revealed consistently high expression of the gene product in the epithelial and blastemal components. These spatial and temporal patterns of expression for Hsal 1, and the phenotypic effects associated with TBS, suggest that Hsal 1 plays an important role in the development and functional maintenance of the kidney and gonads. Furthermore, the Hsal 1 gene product may play a part in the pathogenesis of specific neoplasms occurring in these organs in addition to its specific role in Townes-Brocks syndrome.

Abnormalities, Multiple↗
PubMed2001

Outpatient laparoscopic cholecystectomy. A prospective study with 100 consecutive patients.

One hundred patients with cholelithiasis were included in a prospective consecutive follow-up study to evaluate laparoscopic cholecystectomy in a day surgical setting. The median operating time was 70 min. In 96% of the patients, it was possible to perform peroperative cholangiography. The median time off work was 7 days and the median time to full recovery was 14 days. Five patients were admitted due to weakness/nausea. Six patients were admitted due to conversion to open surgery or choledocholithiasis. Eighty-nine patients were treated in ambulatory surgery. We conclude that laparoscopic outpatient cholecystectomy can be performed safely with a low unplanned admission rate.

Journal Article↗
PubMed2001

A prospective evaluation of the clinical presentation of pediatric pelvic fractures.

BACKGROUND: We sought to describe pediatric, blunt trauma patients with pelvic fracture (PF) and to evaluate pelvis examination sensitivity and specificity. METHODS: We conducted a prospective study of blunt trauma patients at a Level I pediatric trauma center. A pediatric emergency medicine physician attempted to diagnose a PF, solely on the basis of the history and pelvis examination. Patients with blunt trauma but no pelvic fracture (NPF) were used as controls. RESULTS: We enrolled 140 patients (16 PF, 124 NPF), and no significant differences were found regarding median age, gender, injury mechanism, acuity, and medical outcome. Approximately 25% of PF patients had iliac-wing fractures; 37%, single pelvic ring; 25%, double pelvic ring; and 13%, acetabular fractures. Eleven patients with PF had an abnormal pelvis examination (69% sensitivity), compared with six NPF patients (95% specificity, negative predictive value 0.91). CONCLUSION: Pediatric patients with PF have low mortality and few complex fractures. The pelvis examination appears to have both high specificity and negative predictive value.

Adolescent↗
PubMed2000

Helicity dependence of gammap --> Npi below 450 MeV and contribution to the Gerasimov-Drell-Hearn sum rule.

The helicity dependence of the single pion photoproduction on the proton has been measured in the energy range from 200 to 450 MeV for the first time. The experiment, performed at the Mainz microtron MAMI, used a 4pi-detector system, a circularly polarized, tagged photon beam, and a frozen-spin target. The data obtained provide new information for multipole analyses of pion photoproduction and determine the main contributions to the Gerasimov-Drell-Hearn sum rule and the forward spin polarizability gamma(0).

Journal Article↗
PubMed2000

Distinct versus redundant properties among members of the INK4 family of cyclin-dependent kinase inhibitors.

p16(INK4a), p15(INK4b), p18(INK4c) and p19(INK4d) comprise a family of cyclin-dependent kinase inhibitors and tumor suppressors. We report that the INK4 proteins share the ability to arrest cells in G1, and interact with CDK4 or CDK6 with similar avidity. In contrast, only p18 and particularly p19 are phosphorylated in vivo, and each of the human INK4 proteins shows unique expression patterns dependent on cell and tissue type, and differentiation stage. Thus, the INK4 proteins harbor redundant as well as non-overlapping properties, suggesting distinct regulatory modes, and diverse roles for the individual INK4 family members in cell cycle control, cellular differentiation, and multistep oncogenesis.

Binding, Competitive↗