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  • 1
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Magnetic and specific-heat studies of U2T2X compounds show a frequent occurrence of the γ enhancement in conjunction with the onset of antiferromagnetic ordering. The largest value of 830 mJ/mol K2 was observed in U2Pt2In, which is nonmagnetic down to 1.2 K. Variations of electronic structure are documented by optimized relativistic LCAO calculation.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 111 (1999), S. 386-397 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We have studied the ultraviolet laser-induced desorption of NO molecules from an epitaxial film of NiO(100) on Ni(100) for pulse durations of 550 fs and at a photon energy of 3.95 eV. For applied laser intensities up to 450 MW/cm2, the highest intensities employed in this work, a linear dependence of the desorption yield on the laser intensity is observed. A desorption cross section of (1.9±0.3)⋅10−17 cm2 is then derived. The molecules are detected with rovibrational state selectivity by (1+1)-REMPI via the A 2Σ+(v′=0,1,2,3)←X 2Π(v″=0,1,2,3) γ-band transitions. The rotational population distributions are nonthermal, with rotational temperatures of about 290 K at low and of about 770 K at high rotational energies. The relative populations in the 2Π1/2 and 2Π3/2 fine-structure states and of the Λ-doublet states are examined for the given set of (v″,J″) quantum numbers. The vibrational states v″〉0 are significantly populated approaching vibrational temperatures of 3800 K. Velocity distributions of the desorbed molecules are measured for individual rovibrational states. Bimodal distributions with a distinct rotational-translational coupling are observed. Further, molecules desorbing in the excited fine-structure state 2Π3/2 show a higher velocity than those desorbing in 2Π1/2. The results are compared with earlier ones obtained for the same system with nanosecond desorption pulses at hν=6.4 eV. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Small cantilevers allow for faster imaging and faster force spectroscopy of single biopolymers than previously possible because they have higher resonant frequencies and lower coefficients of viscous damping. We have used a new prototype atomic force microscope with small cantilevers to produce stable tapping-mode images (1 μm×1 μm) in liquid of DNA adsorbed onto mica in as little as 1.7 s per image. We have also used these cantilevers to observe the forced unfolding of individual titin molecules on a time scale an order of magnitude faster than previously reported. These experiments demonstrate that a new generation of atomic force microscopes using small cantilevers will enable us to study biological processes with greater time resolution. Furthermore, these instruments allow us to narrow the gap in time between results from force spectroscopy experiments and molecular dynamics calculations. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We present the first photoelectron spectrometry experiment on a singly charged ion beam. Taking advantage of the high photon flux emitted in the undulator SU6 of Super-ACO, we have measured photoelectron spectra produced in the resonant photoionization of Ca+ ions at 33.2-eV photon energy. The success of this experiment depended strongly on the photon flux available. We demonstrate the capability of photoelectron spectrometry to precisely calibrate the photon spectrum emitted in the undulator.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 69 (1996), S. 3662-3664 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Front-illuminated PtSi–n–Si Schottky barrier photodiodes have been developed for the ultraviolet and vacuum ultraviolet spectral range. Their spectral responsivity was determined in the 120–500 nm spectral range by use of a cryogenic electrical substitution radiometer operated with spectrally dispersed synchrotron radiation. For wavelengths below 250 nm, the spectral responsivity is about 0.03 A/W, comparable to that of GaAsP Schottky photodiodes. Unlike the GaAsP diodes, the new PtSi–n–Si diodes have a spatially uniform response which is virtually stable after prolonged exposure to short wavelength radiation. Even after a radiant exposure of 150 mJ cm−2 at wavelength 120 nm, the relative reduction in spectral responsivity remains below 0.2%. Due to these features, this type of photodiode is a promising candidate for use as secondary detector standard in the ultraviolet and vacuum ultraviolet spectral ranges. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1365-3083
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The splenic mononuclear cells (MNC) of rabbits 7-14 and 30-48 days following primary intravenous immunization with sheep erythrocytes generated large numbers of antibody-secreting or plaque-forming cells (PFC) in secondary immune responses induced in vitro, whereas the splenic MNC obtained from rabbits 18-30 days following primary intravenous immunization generated poor secondary immune responses (few PFC) in vitro. However, these latter splenic MNC depleted of T cells consistently generated many PFC in the secondary immune response in vitro. Furthermore, the splenic MNC of rabbits thymectomized prior to day 3 following primary intravenous immunization also generated good secondary immune responses in vitro, irrespective of the time of killing post-immunization, whereas the splenic MNC of rabbits thymectomized after day 7 following primary immunization generated poor secondary immune responses in vitro. These results indicate that the depressed ability of the splenic MNC, obtained from rabbits killed between days 18 and 30 post-primary immunization, to generate significant secondary immune responses in vitro is due to suppressor T cells. The suppressor cells are referred to as immune spleen suppressor cells or ISSC. It was demonstrated that the suppression by the ISSC is antigen-specific and that the ISSC secrete an antigen-specific suppressor factor referred to as immune spleen suppressor factor or ISSF. It is concluded that the ISSC are generated in the thymus within a few days following primary immunization, that they migrate to and infiltrate the spleen between days 3 and 7 following primary immunization, and that they suppress or down-regulate further antibody synthesis via the secretion, locally of ISSF.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The filamentous bacterium Streptomyces coelicolor undergoes a complex process of morphological differentiation involving the formation of a dense lawn of aerial hyphae that grow away from the colony surface into the air to form an aerial mycelium. Bald mutants of S. coelicolor, which are blocked in aerial mycelium formation, regain the capacity to erect aerial structures when exposed to a small hydrophobic protein called SapB, whose synthesis is temporally and spatially correlated with morphological differentiation. We now report that SapB is a surfactant that is capable of reducing the surface tension of water from 72 mJ m−2 to 30 mJ m−2 at a concentration of 50 μg ml−1. We also report that SapB, like the surface-active peptide streptofactin produced by the species S. tendae, was capable of restoring the capacity of bald mutants of S. tendae to erect aerial structures. Strikingly, a member (SC3) of the hydrophobin family of fungal proteins involved in the erection of aerial hyphae in the filamentous fungus Schizophyllum commune was also capable of restoring the capacity of S. coelicolor and S. tendae bald mutants to erect aerial structures. SC3 is unrelated in structure to SapB and streptofactin but, like the streptomycetes proteins, the fungal protein is a surface active agent. Scanning electron microscopy revealed that aerial structures produced in response to both the bacterial or the fungal proteins were undifferentiated vegetative hyphae that had grown away from the colony surface but had not commenced the process of spore formation. We conclude that the production of SapB and streptofactin at the start of morphological differentiation contributes to the erection of aerial hyphae by decreasing the surface tension at the colony surface but that subsequent morphogenesis requires additional developmentally regulated events under the control of bald genes.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular medicine 70 (1992), S. 735-739 
    ISSN: 1432-1440
    Keywords: Kidney ; Calcium ; Phosphate ; Sodium ; Caries
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Clearance studies were performed for 2 days in two groups of age-matched young female volunteers: those with low caries prevalence and those with high caries prevalence. Both groups were kept on a low-calcium diet for 1 week and received 0.5 g calcium at the beginning of the second day. In both groups, glomerular filtration rate, urinary flow rate and renal excretions of sodium, calcium, and phosphate were subject to significant circadian variations. In both groups the administration of calcium led to a significant increase in renal excretion of sodium and calcium and a significant decrease in that of phosphate. On the first day, calcium excretion was significantly greater in those with low caries prevalence than in those with high caries prevalence, pointing to altered calcium homeostasis in this group.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1433-0385
    Keywords: Key words: Odontoid fracture ; Non union ; Pseudarthrosis ; Transarticular screw fixation ; Os odontoideum. ; Schlüsselwörter: Densfraktur ; Pseudarthrose ; operative Behandlung ; konservative Behandlung ; transartikuläre Verschraubung C1/C2 ; Os odontoideum.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung. Einleitung: Die überwiegende Mehrzahl aller Denspseudarthrosen liegt eine vorausgegangene Verletzung zugrunde. Bei dem am häufigsten vorkommende Frakturtyp II mit einem Bruchverlauf im Bereich der Densbasis entsteht auf Grund besonderer anatomischer Bedingungen auch besonders oft ein Falschgelenk. Entscheidende Mechanismen bei seiner Entstehung sind eine ungenügende innere oder äußere Ruhigstellung des Bruchs sowie ein persistierender Frakturspalt. Methoden und Ergebnisse: Bei einer eigenen Nachuntersuchung von 71 Patienten nach operativer Stabilisierung einer Densfraktur mit 2 Schrauben fanden wir 8mal eine Pseudarthrose. Bei 3 Patienten hatte der Abstand zwischen Unfall und Operation mehr als 5 Wochen betragen, 7mal war es nicht gelungen, den Frakturspalt ausreichend anzunähern. Technische Fehler wie eine ungenügende Reposition (n = 1) sowie Schraubenfehllagen (n = 3) waren weitere Ursachen. Ein Os odontoideum muß nach entsprechenden Berichten im Schrifttum und eigenen Erfahrungen bei einem großen Teil der Patienten als Pseudarthrose nach einer Verletzungen der Synchondrose im Kindesalter angesehen werden. Die wichtigste diagnostische Maßnahme bei Denspseudarthrosen stellt eine Funktionsuntersuchung der oberen HWS in maximaler Flexion und Extension dar. Wir schlagen eine Einteilung posttraumatischer Denspseudarthrosen in 4 Typen vor: Typ I entspricht einer straffen „Pseudarthrose“ in weitgehend anatomischer Stellung des Dens axis und ohne Zeichen der Instabilität im ehemaligen Frakturbereich. Typ II beschreibt eine stark verschobene Pseudarthrose, die sich nicht ohne weiteres reponieren läßt, Typ III eine instabile Pseudarthrose und Typ IV ein posttraumatisches Os odontoideum. Schlußfolgerungen: Therapieempfehlungen müssen bei Denspseudarthrosen entsprechend differenziert gegeben werden. Instabile Denspseudarthrosen (Funktionsaufnahmen) verursachen fast immer deutliche Beschwerden und bedürfen wegen der immer wieder beschriebenen Gefahr einer akuten oder chronischen Myelopathie – ebenso wie Ossa odontoidea – der operativen Stabilisierung. Bei erheblich dislozierten Pseudarthrosen sollte zunächst ein geschlossener Repositionsversuch unternommen werden. Operationsmethode der Wahl ist die dorsale transarticuläre Verschraubung und Fusion C1/C2, möglichst in percutaner Technik. Straffe, „stabile“ Denspseudarthrosen im Sinne eines persistierenden Frakturspalts bei beschwerdefreien Patienten sollten anfangs röntgenologisch kontrolliert; bleibt die Stellung des Dens unverändert, kann weiter konservativ behandelt werden.
    Notes: Summary. Introduction: Injuries precede the vast majority of all odontoid pseudarthroses. Because of specific anatomic conditions type II injuries lead more often than other types to non unions. For its development insufficient internal or external fixation and a persisting fracture gap are crucial. Methods and results: In 71 patients after operative stabilization of odontoid fractures with two anterior lag-screws we detected 8 non unions. In 3 patients the interval between accident and operation amounted to more than 5 weeks, seven times we did not succeed in closing the fracture gap. Technical mistakes like insufficient reduction (n = 1) or screw misplacement (n = 3) were additional reasons. According to the literature and own observations an os odontoideum must be considered in most instances as a pseudarthrosis after a lesion of the subdental synchondrosis in childhood. The most important diagnostic tool in odontoid non unions is a dynamic examination of the upper cervical spine under fluoroscopic control in maximum flexion and extension. We propose a classification of posttraumatic dens non unions into 4 types. Type I corresponds to a stable „non union“ in approximate anatomical position of the dens and without signs of instability in the former fracture zone. Typ II describes a relatively stable grossly displaced non union that is not to be reduced by simple, closed means. Typ III means an unstable non union and Typ IV a posttraumatic os odontoideum. Conclusions: Therapeutical recommendations need to be differentiated. Unstable non unions are most often responsible for persistent pain, may result in acute or chronic myelopathie and therefore – as well as ossa odontoidea – need operative fixation. In considerably displaced non unions a closed reduction manoeuver with long term traction should be tried. The operative treatment of choice is the posterior transarticular screw fixation C1/C2 desirably in a percutaneous technique. Tight, “stable” pseudarthroses in the sense of a persisting fracture gap in painfree patients should first be controlled radiologically. If the odontoid position remains unchanged, non operative treatment may be continued.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Der Chirurg 70 (1999), S. 1294-1301 
    ISSN: 1433-0385
    Keywords: Key words: Traumatic knee dislocation ; Knee ligament rupture ; Cruciate ligament reconstruction ; Long-term results ; Prognostic factors. ; Schlüsselwörter: Traumatische Knieluxation ; Kniebandruptur ; Kreuzbandrekonstruktion ; Langzeitergebnisse ; prognostische Faktoren.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung. Einleitung: Die traumatische Luxation ist die schwerste ligamentäre Verletzung des Kniegelenks und tritt mit 0,2–0,3 % aller Gelenkluxationen selten auf. Zur konservativen und operativen Behandlung liegen einige abgeschlossene Langzeitstudien vor. Vor allem aufgrund der meist geringen Fallzahlen sind die Behandlungsempfehlungen und Therapieschemata aber noch immer uneinheitlich. Methoden und Ergebnisse: Zwischen 1974 und 1994 wurden in unserer Klinik 38 Patienten mit dokumentierter Knieluxation operativ behandelt. 34 Patienten konnten nach 3–16 Jahren (Mittelwert: 8,6 Jahre) nachuntersucht werden. Bei 29 der nachuntersuchten Patienten war die Rekonstruktion beider Kreuzbänder erfolgt. Bei den restlichen Fällen erfolgte keine Versorgung der Kreuzbandläsionen. Bei 90 % der nachuntersuchten Patienten wurde eine gute Kniestabilität ermittelt, allerdings bestand auch in 90 % eine Bewegungseinschränkung. Die posttraumatische Arthrose war meist leicht bis mittelschwer; 35 % der Patienten erreichten gute bis sehr gute Ergebnisse im Lysholm-Score. Schlußfolgerungen: Als prognostisch günstige Faktoren erwiesen sich bei dieser Untersuchung ein Alter zum Unfallzeitpunkt von weniger als 40 Jahren, Traumen mit geringer Rasanz, wie z. B. Sportunfälle, eine frühe Rekonstruktion beider Kreuzbänder und eine frühfunktionelle Nachbehandlung.
    Notes: Summary. Introduction: Traumatic dislocation is the most severe ligamentous injury of the knee. The indications for operative and conservative treatment are still controversial. Methods and results: From 1974 to 1994, 38 patients with documented knee dislocation were treated operatively in our department. Thirty-four of these patients were followed up for 3–16 years (mean: 8.6 years). In 29 cases of the follow-up group, reconstruction of both cruciate ligaments was performed. In the remaining cases the cruciate ligaments were left alone. At the time of follow-up, 90 % of the patients showed good knee stability, but 90 % had lack of motion as well. Post-traumatic osteoarthritis was mostly mild to moderate. Thirty-five percents of the patients achieved excellent to good results in the Lysholm Score. Conclusions: Positive prognostic factors were an age less than 40 years at the time of the accident, a low-energy trauma, e. g., a sports-related injury, early reconstruction of both cruciate ligaments, and initial postoperative functional treatment.
    Type of Medium: Electronic Resource
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