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  • 1
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Utilizing the magneto-optic Kerr effect (MOKE) in conjunction with x-ray and neutron reflectometry (NR) and diffraction, we have studied the magnetic coupling of Fe/Cr(001) superlattices grown at room temperature and 250 °C. Only the samples grown at elevated temperature exhibit noncollinear coupling of 5.0 nm Fe layers across 1.7 nm Cr interlayers. The noncollinear samples feature a less-disordered in-plane interfacial structure than those grown at room temperature. Using x-ray diffuse reflectivity, we have measured a length scale of 10 nm for these in-plane features. We have also observed, via NR, a remanent noncollinear coupling angle of 50° and, via MOKE and NR, a gradual approach to saturation at upwards of 7 kOe. These features can be explained qualitatively by the proximity magnetism model of Slonczewski. We will compare the predictions of both the proximity and bilinear/biquadratic models with our data and present the results of ongoing neutron measurements of the temperature dependence of the coupling. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 6432-6438 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Results are outlined of experimental work concerning Slonczewski's theories explaining 90° coupling: "loose spin'' theory and thickness-fluctuation mechanism. The loose spin theory suggests that 90° coupling originates from paramagnetic impurities in the interlayer of an exchange-coupled layered structure. The influence of these paramagnetic impurities on the magnetic exchange coupling was studied using the wedge technique. High-quality single-crystalline Fe/Ag/Fe samples were prepared in UHV and each sample consisted of two wedges: one wedge with additional Fe deliberately inserted during growth into the Ag interlayer and one wedge with a pure Fe/Ag/Fe structure. The detailed analysis of magneto-optic hysteresis loops revealed quantitatively the bilinearly and the 90° coupling strength. As predicted by loose spin theory additional Fe in the Ag spacer lead to a strong temperature dependence of the 90° coupling. According to the theory an increase of 90° coupling strength proportional to impurity concentration was detected while the strength of bilinear coupling decreased. For the pure Fe/Ag/Fe structure, a linear increase of the 90° coupling strength with decreasing temperature was observed. This result can be explained within the fluctuation mechanism which creates 90° coupling through a combination of interface roughness and intralayer ferromagnetic exchange. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science, Ltd
    Anatomia, histologia, embryologia 28 (1999), S. 0 
    ISSN: 1439-0264
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Immediately after ovulation a neovascular response occurs at the level of the theca interna. Pericytes and endothelial cells of post-capillary venules locally remodel the surrounding stroma, elongate and migrate into the avascular granulosa folds of the ruptured follicle. In order to examine the composition of the extracellular matrix as well as the growth characteristics of these newly formed vessels, we used immunohistochemical and electron microscopic methods. Initial sprouts were characterized by the appearance of a fibrillary network of fibronectin along the main axis of the sprout. Type IV collagen stained weakly and extracellular deposits of laminin were amorphous and patchy around immature capillary sprouts. In advanced maturational stages of the sprouts the capillaries were surrounded by increased deposits of fibronectin, whereas laminin and type IV collagen displayed a distinct and well-developed line around endothelial cells and pericytes. These observations indicate that the microvascular extracellular matrix undergoes a series of quantitative rather than qualitative changes during capillary development before achieving final maturation. Ultrastructural analyses showed that early capillary sprouts in the bovine corpus luteum were usually preceded by pericytes migrating at the tips of the sprouts. Endothelial cells comigrated in cohesive cylindrical projections, forming immediately a slit-like lumen which satisfies the criteria of the intercellular canalization type. Pericytes at the tips of endothelial sprouts exhibited a slender, bipolar morphology and were regularly surrounded by fragmented basal lamina, which is well-developed around pericytes in a more proximal position of the sprout. The regular association of pericytes with the leading front of the capillary sprouts suggests that these cell types may serve as guiding structures aiding outgrowth of endothelial cells in the bovine corpus luteum.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1600-5759
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Der Chirurg 68 (1997), S. 977-985 
    ISSN: 1433-0385
    Keywords: Key words: Laparoscopy ; Groin hernia ; Mesh repair ; Laparoscopic hernia repair ; TAPP. ; Schlüsselwörter: Laparoskopie ; Inguinalhernie ; Netzplastik ; laparoskopischer Hernienverschluß ; TAPP.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung. Der Stellenwert der minimal-invasiven Chirurgie zur Therapie von Leistenhernien ist auch heute noch nicht klar definiert. Der aktuelle Standard zur Versorgung einer Primärhernie entspricht in Europa einem offenen Verfahren (Shouldice) ohne Implantation von Fremdmaterial. Der Vorteil der Netzimplantation liegt in der Versorgung von komplizierten Bruchformen mit einem vorhandenen myopektinealen Defekt sowie Rezidiv- und Bilateralhernien. Hier kann die minimal-invasive Technik trotz dem erhöhten Schwierigkeitsgrad der Operation und der direkten Mehrkosten Vorteile bieten. Ob ein transabdomineller (TAPP) oder ein präperitonealer Zugang (TEP) bevorzugt wird, hängt von der Art des Bruches, dem Patientenrisiko und der Erfahrung des Operateurs ab. Beide Techniken der minimal-invasiven Chirurgie (TAPP und TEP) sind bzgl. Morbidität und Langzeitverlauf vergleichbar. Die Vorteile der TAPP-Reparation liegen in der einfacheren Technik, dem größeren Arbeitsraum und der guten Diagnostik.
    Notes: Summary. The value of the minimal invasive approach for treating groin hernias is not yet well defined. The standard treatment for primary hernia repair in Europe is an open approach (i.e. Shouldice) without mesh implantation. A mesh may be used to repair a so-called complicated hernia with a complete myopectineal defect, as well as for recurrent and bilateral hernias. These hernias can well be treated laparoscopically despite the fact that the approach is difficult and that there is an increase of direct costs. Whether or not a transabdominal (TAPP) or preperitoneal (TEP) endoscopic approach is used depends on the type of hernia, the risk to the patient, and the surgeon's experience. Morbidity and long-term follow-up are identical for both techniques (TAPP and TEP). The advantages for TAPP repair are that the technique is simpler, with a large working space and good diagnostic tools.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-1912
    Keywords: Key words Hypoxia ; Neocortex ; KATP channels ; Purine nucleotides ; Pyrimidine nucleotides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In a first series of experiments, intracellular recordings were made from pyramidal cells in layers II–III of the rat primary somatosensory cortex. Superfusion of the brain slice preparations with hypoxic medium (replacement of 95% O2–5% CO2 with 95% N2–5% CO2) for up to 30 min led to a time-dependent depolarization (HD) without a major change in input resistance. Short periods of hypoxia (5 min) induced reproducible depolarizations which were concentration-dependently depressed by an agonist of ATP-dependent potassium (KATP) channels, diazoxide (3–300 µM). The effect of 30 but not 300 µM diazoxide was reversed by washout. Tolbutamide (300 µM), an antagonist of KATP channels, did not alter the HD when given alone. It did, however, abolish the inhibitory effect of diazoxide (30 µM) on the HD. Neither diazoxide (3–300 µM) nor tolbutamide (300 µM) influenced the membrane potential or the apparent input resistance of the neocortical pyramidal cells. Current-voltage (I-V) curves constructed at a membrane potential of –90 mV by injecting both de- and hyperpolarizing current pulses were not altered by diazoxide (30 µM) or tolbutamide (300 µM). Moreover, normoxic and hypoxic I-V curves did not cross each other, excluding a reversal of the HD at any membrane potential between –130 and –50 mV. The hypoxia-induced change of the I-V relation was the same both in the absence and presence of tolbutamide (300 µM). In a second series of experiments, nucleoside di- and triphosphates separated with anion exchange HPLC were measured in the neocortical slices. After 5 min of hypoxia, levels of nucleoside triphosphates declined by 29% (GTP), 34% (ATP), 44% (UTP) and 58% (CTP). By contrast, the levels of nucleoside diphosphates either did not change (UDP) or increased by 13% (GDP) and 40% (ADP). In slices subjected to 30 min of hypoxia the triphosphate levels continued to decrease, while the levels of GDP and ADP returned to control values. The tri- to diphosphate ratios progressively declined for ATP/ADP and GTP/GDP, but not for UTP/UDP when the duration of hypoxia was increased from 5 to 30 min. Hence, the rapid fall in the ratios of nucleoside tri- to diphosphates without the induction of a potassium current failed to indicate an allosteric regulation of a plasmalemmal KATP channel by purine and pyrimidine nucleotides. Diazoxide had no effect on neocortical pyramidal neurons and was effective only in combination with a hypoxic stimulus; it is suggested that both plasmalemmal and mitochondrial KATP channels are involved under these conditions. The hypoxic depolarization may be due to blockade of K+,Na+-ATPase by limitation of energy supplying substrate.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-0649
    Keywords: 42.55.Px ; 42.62.Fi ; 07.65.Gj
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We present an optically stabilized lead-salt diode-laser system which is the nucleus of a very-high-resolution instrument for sub-Doppler molecular spectroscopy in the mid-infrared. By application of external optical feedback, we have narrowed the diode-laser linewidth by two orders of magnitude, yielding a spectral width of less than 200 kHz. The diode- laser frequency is stabilized and controlled via the external reflector by variable-frequency offset-locking the diode-laser to a CO laser frequency. This substantial improvement in the spectral properties enabled us to perform a Lamb-dip experiment on a carbonyl sulfide (OCS) absorption line near 1985 cm−1. We were able to detect a saturated dispersion signal at low pressure (5 Pa) with a signal-to-noise ratio of several thousand. The present paper describes the unique features of the optically stabilized tunable diode-laser system and its use as a spectroscopic tool for sub-Doppler applications.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Der Nervenarzt 69 (1998), S. 873-878 
    ISSN: 1433-0407
    Keywords: Schlüsselwörter Stammganglienverkalkung ; Hypoparathyreoidismus ; Alport-Syndrom ; Kalzium-Stoffwechsel ; Key words Basal ganglia calcification ; Hypoparathyroidism ; Alport-Syndrome ; Calcium-metabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary In most patients with basal ganglia calcification no disturbance of calcium metabolism is present. We present four patients with basal ganglia calcification. Two suffered from a secondary hypoparathyroidism following a complicated strumectomy years ago, one had an Alport-Syndrome and hypoparathyroidism. Her mother showed basal ganglia calcification and an abortive Alport-Syndrome as well, but no hypoparathyroidism.
    Notes: Zusammenfassung Bei den meisten Patienten mit Stammganglienverkalkung läßt sich keine Störung des Kalziumstoffwechsels nachweisen. Wir stellen 4 Patienten mit Stammganglienverkalkungen vor. Bei 2 Patienten lag ein sekundärer Hypoparathyreoidismus bei Zustand nach komplizierter Strumektomie vor, bei einer weiteren ein Alport-Syndrom und Hypoparathyroidismus. Die Mutter letzterer Patientin zeigte ebenfalls Stammganglienverkalkungen und ein abortives Alport-Syndrom, aber keinen Hypoparathyreoidismus.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1433-0407
    Keywords: Schlüsselwörter Elektrokonvulsionstherapie ; Manie ; Bipolare Störungen ; Kardiale Rhythmusstörungen ; Key words Electroconvulsive therapy ; Mania ; Bipolar disorder ; Cardiac arrhythmia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Despite newly developed pharmacological possibilities, treatment of acute mania may still be a problem in single patients. Independent of the first choice of medication, i.e. neuroleptics, lithium, carbamazepine or valproate, the average response rate is only approximately 50–70%. Therefore, treating mania often implies a number of monotherapeutic and polypharmaceutic attempts for several months, until a sufficient mood stabilization has been reached. The aim of this case report is to remind that electroconvulsive therapy (ECT) is still in use for treating mania, which has been widely neglected in Germany despite its high success rate, mainly reported from Anglo-Saxon countries. As demonstrated in this report, ECT may be a useful tool for a fast antimanic response in patients which may be either refractory to standard treatment or are medically severely ill, and should, in our opinion, therefore be considered already at an earlier stage of treatment in this group. However, persistence of improvement can usually only be achieved with the overlapping start of drug treatment unless the option of maintenance ECT is given.
    Notes: Zusammenfassung Trotz der Vielzahl der in jüngerer Zeit entdeckten pharmakotherapeutischen Möglichkeiten gestaltet sich die Behandlung der akuten Manie im Einzelfall oft schwierig. Unabhängig von der Auswahl des zunächst eingesetzten Medikamentes, sei es ein Neuroleptikum, Lithium, Carbamazepin oder Valproat, beträgt die Ansprechquote im Schnitt doch nur maximal 50–70%. Oft ist daher die Maniebehandlung durch eine Vielzahl monotherapeutischer und additiver Behandlungsversuche über mehrere Monate gekennzeichnet, bis sich eine hinreichende Affektstabilisierung zeigt. Anhand der hier beschriebenen Kasuistik soll daher an die Möglichkeit der Elektrokonvulsionstherapie (EKT) in der Maniebehandlung erinnert werden, die trotz der in der angelsächsischen Literatur berichteten hohen Erfolgsquote in Deutschland stark in den Hintergrund getreten ist. Wie die Kasuistik aufzeigt, kann sie gerade bei pharmakotherapeutisch nur schwer zu behandelnden und zugleich auch internistisch erkrankten Patienten einen schnellen Heilungserfolg bringen, und sollte daher auch bei dieser Patientengruppe frühzeitiger erwogen werden. Wie die Kasuistik aber auch zeigt, läßt sich, sofern die Option der Erhaltungs-EKT nicht umsetzbar ist, der Behandlungserfolg in der Regel nur durch eine überlappend einsetzende Pharmakotherapie aufrecht erhalten.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1432-055X
    Keywords: Schlüsselwörter Hypotension ; Monitoring ; Elektroenzephalogramm ; Früh akustisch evozierte Potentiale (FAEP) ; Key words Hypotension ; Monitoring ; Electroencephalogram ; Brain-stem auditory evoked potentials (BAEP)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract For surgical removal of a malignant choroid melanoma, it is necessary to reduce systolic blood pressure to around 50–60 mmHg in order to prevent choroidal haemorrhages. However, blood pressure reduction is associated with the risk of cerebral ischaemia. We report a patient with a malignant choroid melanoma in whom waves I and II of the brainstem auditory evoked potentials (BAEP) disappeared during surgery under controlled arterial hypotension and hypothermia (31.1° C). The waves could be recorded again immediately after the mean arterial pressure was increased from 48 to 77 mmHg. The oesophageal temperature had dropped by 0.3° C at this time. The 2-channel electroencephalogram (EEG) showed no irregularities during this time period. A bilateral, reversible, apparently blood-pressure-dependent loss of waves I and II during arterial hypotension despite a normal EEG has to our knowledge not been previously described in the literature. The isolated loss of waves I and II with maintenance of waves III, IV, and V is unusual. The literature contains reports of acoustic neurinoma patients in whom only wave V could be recorded. This is regarded as an indication of continued impulse conduction despite the loss of waves I to IV. Others have observed a patient with temporary and reversible loss of BAEP wave I due to vasospasm of the internal auditory artery that apparently occurred during or shortly after manipulation of the internal auditory meatus. Assuming anatomic peculiarities in the blood supply to the generators of the BAEP waves, a stenosis of the basilar artery could be considered as the cause of the bilateral reversible loss of waves I and II. Another potential source could be the induced hypothermia, but this does not seem very likely because the patient's temperature was 0.3° C lower at the return of the waves than at their loss.
    Notes: Zusammenfassung Wir berichten über einen Patienten mit einem malignen Melanom der Aderhaut, bei dem es intraoperativ unter kontrollierter Hypotension und Hypothermie (31,3° C) zum Verlust der Wellen I und II der frühen akustisch evozierten Potentiale (FAEP) kam. Nach Anhebung des mittleren arteriellen Drucks von 48 auf 77 mmHg waren die FAEP-Wellen sofort wieder ableitbar, obwohl die ösophageale Temperatur um 0,3° C abgefallen war. Das ebenfalls abgeleitete 2-Kanal-Elektroenzephalogramm (EEG) zeigte im betreffenden Zeitraum keine Auffälligkeiten. Ein beidseitiger reversibler, offensichtlich blutdruckabhängiger Ausfall der Wellen I und II während Hypotension bei gleichzeitig unauffälligem EEG ist unseres Wissens bisher in der Literatur nicht beschrieben. Der isolierte Verlust der Wellen I und II bei erhaltenen Wellen III, IV und V ist ungewöhnlich. In der Literatur sind aber Patienten mit Akustikusneurinom beschrieben, bei denen nur die Welle V abgeleitet werden konnte. Ebenso ist ein Fall mit temporärem Verlust von FAEP-Welle I beschrieben. Als Ursache wird eine lokale Minderperfusion wegen Vasospasmus während Manipulationen in Strukturen des Meatus akustikus internus diskutiert. Ausgehend von anatomisch-physiologischen Besonderheiten der Blutversorgung der Generatoren der FAEP-Wellen kann eine Stenose der Arteria basilaris als Ursache für den beidseitigen reversiblen Ausfall der Wellen I und II diskutiert werden. Der Erhalt der Wellen III bis V könnte für eine retrograde Füllung der A. basilaris aus dem Stromgebiet des Circulus Willisii sprechen. Wir interpretieren den beidseitigen Ausfall der Wellen I und II als Folge der Minderperfusion des betreffenden Hirngewebes. Die gleichzeitig bestehende Hypothermie scheidet als Ursache für den temporären Verlust der Wellen I und II aus, weil die Temperatur des Patienten beim Wiederauftreten der Wellen I und II 0,3° C niedriger war als bei ihrem Verlust.
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