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Biomedical subjects

H Ott

Publications and source records attributed to H Ott.

At least 19 recordsLinked to original sources
PubMed2005

Spectroscopy of stripe order in La1.8Sr0.2NiO4 using resonant soft x-ray diffraction.

Strong resonant enhancements of the charge-order and spin-order superstructure-diffraction intensities in La1.8Sr0.2NiO4 are observed when x-ray energies in the vicinity of the Ni L2,3 absorption edges are used. The pronounced photon-energy and polarization dependences of these diffraction intensities allow for a critical determination of the local symmetry of the ordered spin and charge carriers. We found that not only the antiferromagnetic order but also the charge-order superstructure resides within the NiO2 layers; the holes are mainly located on in-plane oxygens surrounding a Ni2+ site with the spins coupled antiparallel in close analogy to Zhang-Rice singlets in the cuprates.

Journal Article↗
PubMed2005

[Special features of the skin in newborns and young infants].

Detailed knowledge of the special features of neonatal and infant skin is a prerequisite for adequate skin care in this age group. Immediately postpartum, the newborn baby's skin assumes vital functions regarding water and electrolyte homeostasis and thermoregulation, as well as innate and adaptive host defense. Due to its functional and structural immaturity, premature skin requires special care. Mature neonates demonstrate benign, transient skin lesions that do not require specific therapy but have to be distinguished from serious and potentially life-threatening illnesses.

Humans↗
PubMed2005

[Dermatologic manifestations of infections in pediatric cancer patients].

Cutaneous infections in children and adolescents with cancer are frequently associated with a marked morbidity and mortality. Particularly neutropenic patients undergoing intensive cytostatic therapy or after allogenic stem cell transplantation are affected. In this group of patients, atypical manifestations of infectious skin disease are frequently observed which represent a diagnostic challenge. It is therefore essential for clinicians to be familiar with the clinical presentation, diagnostic methods and management of skin infections encountered in pediatric oncology.

Adolescent↗
PubMed2005

Cell- and gene therapy for ischemic heart disease.

Despite advances in pharmacological therapies, cardiovascular surgery, use of mechanical assist devices, and organ transplantation, more than half of the patients with clinically evident heart failure die within 5 years of the initial diagnosis. The use of cellular cardiomyoplasty and gene therapy offer a promising approach for both the prevention and treatment of heart failure. This review will discuss the current state of these emerging fields and the prospects of introducing the methods into clinical practice. Since functional restoration of the damaged heart presents a formidable challenge, developing strategies for the prevention of post-infarct heart failure remains of utmost priority. New strategies to optimize cell delivery, homing and survival on the one side and safe and efficient application of gene therapy to the failing myocardium on the other side are indispensable in order to achieve myocardial recovery after acute infarction or chronic ischemic damage.

Animals↗
PubMed2004

Finite-size effect on magnetic ordering temperatures in long-period antiferromagnets: holmium thin films.

The thickness dependence of the helical antiferromagnetic ordering temperature T(N) was studied for thin Ho metal films by resonant magnetic soft x-ray and neutron diffraction. In contrast with the Curie temperature of ferromagnets, T(N) was found to decrease with film thickness d according to [T(N)(infinity)-T(N)(d)]/T(N)(d) proportional variant (d-d(0))(-lambda(')), where lambda(') is a phenomenological exponent and d(0) is of the order of the bulk magnetic period L(b). These observations are reproduced by mean-field calculations that suggest a linear relationship between d(0) and L(b) in long-period antiferromagnets.

Journal Article↗
PubMed2004

Radio frequency selective addressing of localized atoms in a periodic potential.

We study the localization and addressability of ultracold atoms in a combined parabolic and periodic potential. Such a potential supports the existence of localized stationary states and we show that applying a radio frequency field allows us to selectively address atoms in these states. This method is used to measure the energy and momentum distribution of the atoms in the localized states. We also discuss possible extensions of this scheme to address and manipulate atoms in single lattice sites.

Journal Article↗
PubMed2004

Insulating behavior of a trapped ideal Fermi gas.

We investigate theoretically and experimentally the center-of-mass motion of an ideal Fermi gas in a combined periodic and harmonic potential. We find a crossover from a conducting to an insulating regime as the Fermi energy moves from the first Bloch band into the band gap of the lattice. The conducting regime is characterized by an oscillation of the cloud about the potential minimum, while in the insulating case the center of mass remains on one side of the potential.

Journal Article↗
PubMed2004

Atom interferometry with trapped fermi gases.

We realize an interferometer with an atomic Fermi gas trapped in an optical lattice under the influence of gravity. The single-particle interference between the eigenstates of the lattice results in macroscopic Bloch oscillations of the sample. The absence of interactions between fermions allows a time-resolved study of many periods of the oscillations, leading to a sensitive determination of the acceleration of gravity. The experiment proves the superiority of noninteracting fermions with respect to bosons for precision interferometry and offers a way for the measurement of forces with microscopic spatial resolution.

Journal Article↗
PubMed2004

Collisionally induced transport in periodic potentials.

We study the transport of ultracold atoms in a tight optical lattice. For identical fermions the system is insulating under an external force while for bosonic atoms it is conducting. This reflects the different collisional properties of the particles and reveals the role of interparticle collisions in establishing a macroscopic transport in a perfectly periodic potential. Also in the case of fermions we can induce a transport by creating a collisional regime through the addition of bosons. We investigate the transport as a function of the collisional rate and observe a transition from a regime in which the mobility increases with increasing collisional rate to one in which it decreases. We compare our data with a theoretical model for electron transport in solids introduced by Esaki and Tsu.

Journal Article↗
PubMed2004

[Adiponecrosis subcutanea neonatorum in congenital pneumonia].

In the course of a connatal pneumonia, a 7-day-old female newborn developed symmetrical subcutaneous nodules on her back, shoulders, and upper arms. These skin lesions were accompanied by hypercalcemia. Histological examination confirmed the putative clinical diagnosis of subcutaneous fat necrosis of the newborn. We discuss the differential diagnoses, therapeutic strategies, and prognosis of this uncommon disorder of the fat tissue.

Biopsy↗
PubMed2004

[Progressive symmetric erythrokeratodermia of Darier-Gottron].

A 5 1/2-year-old boy revealed symmetric erythematous plaques on both arms and legs as well as in the face. Additionally, contractions of several digital joints were noted. We diagnosed a progressive symmetric erythrokeratoderma and initiated a topical therapy with tretinoin. Here we discuss the etiology, differential diagnoses, and therapeutic options of this rare disorder of keratinization.

Administration, Topical↗
PubMed2004

[Incontinentia pigmenti in a five-week-old girl].

Shortly after birth, a five-week-old female infant developed small blisters and erythema that followed the lines of Blaschko on the upper and lower extremities as well as the abdomen. Histological examination confirmed the clinical presumptive diagnosis of incontinentia pigmenti. We discuss the dinical features, diagnosis, and the molecular genetic basis of this rare inherited skin disorder.

Biopsy↗
PubMed2004

[Identification of geophilic and zoophilic dermatophytes in siblings with tinea capitis. A pathogenic factor or contamination?].

Two siblings of African origin presented with multiple scaling patches and alopecia on the scalp four weeks after returning from a vacation in Eritrea. Direct KOH examination revealed fungal elements; Trichophyton mentagrophytes and Trichophyton terrestre were identified in the fungal culture. We discuss the putative pathogenic role of both microorganisms in causing disease. Although infection with Microsporum canis currently accounts for almost fifty percent of all cases of tinea capitis in Germany, other fungi have gained importance due to tourism and increasing migration.

Alopecia↗
PubMed2004

Robotic totally endoscopic coronary artery bypass: program development and learning curve issues.

BACKGROUND: The introduction of new procedures in heart surgery is a critical phase that includes learning curves and the risk of increased mortality or morbidity. Totally endoscopic coronary artery bypass grafting using robotic techniques represents such an innovative procedure. The aim of this report is to demonstrate the safe introduction of totally endoscopic coronary artery bypass grafting using a stepwise and modular approach. METHODS: From June 2001 until December 2002, 50 procedures were performed using the da Vinci telemanipulator system. After baseline training the following procedure modules were carried out in a stepwise manner: robotically assisted endoscopic left internal thoracic artery harvesting and completion of the procedure as conventional coronary artery bypass grafting, minimally invasive direct coronary artery bypass, or off-pump coronary artery bypass (n = 19), robotically assisted suturing of left internal thoracic artery to left anterior descending anastomoses during conventional coronary artery bypass grafting (n = 15), totally endoscopic coronary artery bypass grafting on the arrested heart using remote access perfusion and aortic endocclusion coronary bypass grafting (n = 15). One patient was excluded intraoperatively from a robotic procedure due to pleural adhesions. RESULTS: A significant learning curve was observed for left internal thoracic artery takedown time, y(min) = 181 - 39 x ln(x) (x = procedure number) (P <.001), and total operative time in totally endoscopic coronary artery bypass grafting, y(min) = 595 - 87 x ln(x) x = (procedure number) (P =.028). The conversion rate in totally endoscopic coronary artery bypass grafting was 2/15. Intensive care unit stay correlated significantly with total operative time (r =.427, P =.002). There was no hospital mortality. CONCLUSION: Totally endoscopic coronary artery bypass grafting can be safely implemented into a heart surgery program. Learning curves are steep for robotic left internal thoracic artery takedown and for performance of totally endoscopic coronary artery bypass grafting. Long operative times translate into prolonged intensive care unit stay in specific cases but not into increased mortality.

Adult↗
PubMed2004

Cell therapy for ischemic heart disease.

Despite advances in pharmacological therapies, cardiovascular surgery, use of mechanical assist devices, and organ transplantation, more than 50% of the patients with clinically evident heart failure die within 5 years of the initial diagnosis. The use of cellular therapy offers a promising approach for both the prevention and treatment of heart failure. This review will discuss the current state of this emerging field and the prospects to introduce the method into clinical practice. Since functional restoration of the damaged heart presents a formidable challenge, developing strategies for the prevention of postinfarct heart failure remains of utmost priority. Recent research has provided evidence that several cell lines including adult or embryonic stem cells, skeletal myoblasts, fetal cardiomyocytes or fibroblasts may be useful in strategies that aim to both prevent and treat heart failure through establishment of new blood vessels supplying surviving heart muscle cells and replacement of damaged heart muscle cells themselves. It is therefore reasonable to anticipate that new strategies will be developed to optimize cell delivery, homing and survival in the failing myocardium improving myocardial recovery after acute or chronic deterioration.

Animals↗
PubMed2003

In situ photoemission study of the room temperature ferromagnet ZnGeP2:Mn.

The chemical states of the ZnGeP(2):Mn interface which shows ferromagnetism above room temperature have been studied by photoemission spectroscopy. Mn deposition on the ZnGeP2 substrate heated to 400 degrees C induced Mn substitution for Zn and then the formation of metallic Mn-Ge-P compounds. Depth profile studies have shown that Mn 3d electrons changed their character from itinerant to localized along the depth, and in the deep region, dilute divalent Mn species (<5% Mn) was observed with a coexisting metallic Fermi edge of non-Mn 3d character. The possibility of hole doping through Mn substitution for Ge and/or Zn vacancy is discussed.

Journal Article↗
PubMed2003

Nonlinear dynamics of a Bose-Einstein condensate in a magnetic waveguide.

We have studied the internal and external dynamics of a Bose-Einstein condensate in an anharmonic magnetic waveguide. An oscillating condensate experiences a strong coupling between the center of mass motion and the internal collective modes. Because of the anharmonicity of the magnetic potential, not only the center of mass motion shows harmonic frequency generation, but also the internal dynamics exhibit nonlinear frequency mixing. Thereby, the condensate shows shape oscillations with an extremely large change in the aspect ratio of up to a factor of 10. We describe the data with a theoretical model to high accuracy. For strong excitations we test the experimental data for indications of a chaotic behavior.

Journal Article↗