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  • 1
    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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  • 2
    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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  • 3
    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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  • 4
    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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  • 5
    ISSN: 1433-0431
    Keywords: Key words Cervical spine • Traumatic atlantoaxial instability • Transarticular screw Fixation C1/C2 • Minimally invasive technique ; Schlüsselwörter Halswirbelsäule • Atlantoaxiale Instabilität • Transartikuläre Verschraubung C1/C2 • Minimal-invasive Technik
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Die Spondylodese C1/C2 mit dorsaler transartikulärer Verschraubung stellt bei traumatischen atlantoaxialen Instabilitäten das Verfahren der Wahl dar. Beim offenem Vorgehen müssen die empfindlichen Weichteile des Nackens bis zum 7. Halswirbel freigelegt werden, um die Bohrmaschine weit genug absenken und die Schrauben steil genug einbringen zu können. Zur Verringerung des Weichteiltraumas wurden deshalb von verschiedenen Autoren eine perkutane Technik angegeben. Wir analysierten die von uns mit beiden Verfahren behandelten Patienten der Jahre 1995–1998, um zu prüfen, ob die perkutane Technik Vorteile bietet. 30 Patienten mit traumatischer sagittaler atlantoaxialer Instabilität wurden von dorsal transartikulär verschraubt. 19mal verwendeten wir die perkutane Technik mit Hilfe des Spezialinstrumentariums von McGuire und Harkey. Anhand der postoperativen Röntgenaufnahmen wurde in der Sagittalebene der Winkel zwischen Axisgrundplatte und Schrauben gemessen; 6–24 Monate nach dem Unfall wurden 26 Patienten nachuntersucht, 4 waren zum Zeitpunkt der Nachuntersuchung verstorben. Der Schraubenwinkel war bei der perkutanen Technik größer als beim offenen Vorgehen. Die Mittelwerte (M) beider Gruppen unterschieden sich um 10 ° (perkutan: M = 73,9 °, offen: M = 63,9 °, t-Test: p = 0,001). Die Operationszeit bei perkutaner Technik war im Schnitt 35 min kürzer (93 zu 128 min, t-Test: p = 0,05). Jeweils 2 Patienten beider Gruppen verstarben aufgrund von Begleitverletzungen oder maligner Erkrankungen. Bei der Nachuntersuchung von 26 Patienten waren alle Spondylodesen radiologisch durchbaut. Die Schraubenlage hatte sich nur in einem Fall mit offener Technik geringfügig geändert. Die Beweglichkeit der HWS war in beiden Gruppen gleich stark eingeschränkt. Die subjektive Beurteilung bezüglich Schmerzfreiheit und Funktion mit Hilfe einer Visualanalogskala und eines speziellen Erfassungsbogens ergab Vorteile zugunsten der Gruppe mit perkutaner Technik (z. B.: Schmerzfreiheit: 43 (perkutan) zu 39 (offen) Punkte, t-Test: p = 0,05). Vor der Verletzung hatten die Patienten beider Gruppen vergleichbare Scores aufgewiesen. Die weichteilschonende, perkutane Technik der transartikulären Verschraubung C1/C2 unter Verwendung eines Spezialinstrumentariums erlaubt eine bessere und einfachere Schraubenplazierung. Dies führt auch zu einer kürzeren Operationszeit und – vermutlich durch geringere Schädigung der Nackenmuskulatur – zu besseren subjektiven Ergebnissen. Die Methode besitzt besonders große Vorteile bei solchen Patienten, die nur eine temporäre Stabilisierung des C1/C2-Komplexes ohne Fusion benötigen.
    Notes: Summary For posttraumatic atlantoaxial instabilities posterior transarticular screw fixation according to Magerl represents the treatment of choice. In order to be able to insert the screws steep enough the soft tissues of the neck have to be dissected down to C7. Several authors therefore described a percutaneous technique. We analysed 30 patients with a sagittal atlantoaxial instability treated with one of both methods between the years 1995 and 1998 to detect amny differences of either technique. In 19 cases we used a modified percutaneous technique with special instruments as has been published by McGuire and Harkey. On lateral plain films the angle between the screws and the lower endplate of C2 was measured. 6 to 24 months after the accident 26 patients could be seen clinically and controlled radiologically, 4 patients had died in the meanwhile. The angle of the screws were significantly different with 10 degrees (percutaneous group 73,9 degrees, open group 63,9 degrees, p = 0,001). Time needed for the operativ procedure averaged 35 minutes shorter with the canulated technique (93 to 128 minutes, p = 0.05). All posterior fusions had healed radiologically. Active motion of the c-spine was restricted in both groups equally. We checked subjective criteria concerning pain and function with a visual analog scale and a special score. With these instruments advantages for the percutaneous procedure could be found (freedom of pain 43 points (percutaneous) versus 39 points (open), p = 0.05). We conclude that the soft tissue preserving percutaneous technique of screw application for C1/C2 posterior fusion allows for a better and easier placement of screws. It also leads to a shorter operating time and better subjective results. The method offers particularly advantages in cases where only a temporary satbilization of the C1/C2 complex without a regular fusion is needed.
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  • 6
    ISSN: 1433-044X
    Keywords: Key words Car accident • Fracture of the foot • Injury mechanism • Long-term outcome ; Schlüsselwörter PKW-Unfall • Fußfraktur • Verletzungsmechanismus • Langzeitfolgen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Bei 6378 Verkehrsunfällen mit 8931 Verletzten zwischen 1973 und 1989 im Großraum Hannover wurden 3267 PKW-Insassen mit Frakturen registriert. Davon hatten 148 (4,5 %) Personen Frakturen im Fußbereich erlitten. Die Unfalldaten wurden in Hinblick auf Verletzungsentstehung, -art und -ausmaß ausgewertet und die Verletzungsfolgen anhand von Langzeituntersuchungen evaluiert. Bei der Entstehung der Fußfrakturen spielte die Deformierung des Fußraums die wesentliche Rolle. Fahrer und Beifahrer erlitten ähnlich schwere Verletzungen. Bei den 286 Frakturen war der Vorfuß am häufigsten betroffen (45 %), gefolgt von OSG (35 %), Mittelfuß (11 %) und Rückfuß (6 %). Der Anteil der offenen Frakturen betrug 5 %. Die Klassifikation erfolgte nach der „Abbreviated Injury Scale“ (AIS) für die untere Extremität. Die Langzeitfolgen wurden anhand der fußverletzungsbedingten Minderung der Erwerbsfähigkeit (MdE) im Verhältnis zur gesamten MdE abgeschätzt. Diese Auswertung ergab, daß die Fußfrakturen vor allem bei erheblichen Begleitverletzungen bei der Primäruntersuchung oft nicht erkannt oder unterschätzt wurden. Die Langzeitfolgen gingen häufig mit einer erheblichen fußverletzungsbedingten Invalidisierung einher.
    Notes: Summary During 1973 and 1989, 6,378 car accidents with 8,931 injured persons were evaluated in the area of Hannover. 3,267 car drivers and passengers sustained fractures overall and 148 (4,5 %) fractures of the foot. A major role in the ethiology of the foot fractures evolves from the deformation of the foot room. Driver and front seat passenger showed similar injuries. Among the 286 single fractures, the forefoot was affected most often (45 %), followed by ankle (38 %), midfoot (11 %) and hindfoot (6 %). 5 % were open fractures. The long term results were estimated upon the limitation of working ability caused by the foot injury in relation to the entire working ability. The evaluation concludes that the foot fractures especially in combination with other injuries were frequently not recognized within the primary examination and therefore underestimated. The long-term outcome leaded to a high degree of impairment due to foot fractures.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1433-0431
    Keywords: Key words Car accident • Whiplash-type neck distortion ; Duration of complaints • Injury mechanism ; Prognostic factors ; Schlüsselwörter PKW-Unfall • HWS-Distorsion • Beschwerdedauer • Verletzungsmechanismus • Prognostische Faktoren
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Bei einer Unfallanalyse von 3.838 gurtgeschützten, angeschnallten PKW-Fahrer/-innen stieg der Anteil der HWS-Distorsionen von unter 10 % 1985 auf über 30 % 1997. Überwiegend traten diese bei frontalen oder mehrfachen Kollisionen auf. Nur bei 15 % der Patienten wurde die Verletzung durch einen reinen Heckanprall ausgelöst. In 23,2 % betrug δv 10 km/h und weniger, was einem sehr leichten Unfall entspricht. Bei frontalen Kollisionen wurde das höchste durchschnittliche δv erreicht; 1.136 der Verletzten wurden angeschrieben, um Dauer und Art eventueller Beschwerden zu ermitteln. Von den 138 Patienten, die den Fragebogen zurücksendeten gaben 121 (88 %) Beschwerden an. Es handelte sich dabei um Schmerzen (74 %), Verspannungen (6 %) und Bewegungseinschränkungen (5 %) im Bereich von Kopf (27 %), Nacken (55 %) und Schulter (8 %). Die Dauer der Beschwerden war am längsten nach mehrfachen Kollisionen und einem Beschwerdebeginn nach mehr als 24 h. Neben einem geringen Einfluß der Begleitverletzungen auf die Beschwerdedauer sind auch die individuelle Konstitution und Schmerzverarbeitung wesentliche Faktoren. Auch bei dieser retrospektiven Untersuchung bestanden erhebliche Schwierigkeiten hinsichtlich der Nachuntersuchung. Zur Lösung dieses Problems sind prospektive Studien mit genau festgelegten Protokollen zur Erfassung von Diagnose, Behandlungsart sowie Beschwerdedauer und -art erforderlich.
    Notes: Summary The analysis of 1,176 whiplash-type neck distortions was sought from a total of 3,838 restrained car driver incident reports. The percentage of these injuries increased from less than 10 % in 1985 to over 30 % in 1997. These occurred mostly with head-on or with multiple collisions, and only in 15 % with pure rear-end collisions. In 23,2 %, δv amounted 10 km/h or less, which corresponds to a very minor crash. The average δv was the highest in the cases of head-on collisions. Letters were sent to the injured to find out about the duration and type of complaints caused by a cervical spine injury. Of the 138 patients who returned the questionnaires, 121 (88 %) indicated that they had or were still suffering from their symptoms. Percentage of various complaints were as follows: pain (74 %), tension (6 %) and stiffness (5 %) in the head (27 %), neck (55 %) and shoulder (8 %). The duration of the complaints was longest after multiple collisions and when the onset of complaints was later than 24 hours after trauma. Women and elderly persons predominated slightly in the group with longer duration of complaints. A correlation between the severity of the accompanying injuries and duration of complaints occurred. Also, with this retrospective study there was considerable difficulties in the lack of adequate follow-up for these patients with less severe injuries. In order to better evaluate this problem, prospective studies are necessary which include documentation of diagnosis, treatment protocols, duration and type of complaints.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Monatsschrift Kinderheilkunde 146 (1998), S. 972-975 
    ISSN: 1433-0474
    Keywords: Schlüsselwörter Hypoton-hyporesponsive Episode ; Impfung ; Unerwünschtes Ereignis ; Azelluläre Pertussisvakzine ; Key words Hypotonic-hyporesponsive episode ; Immunization ; Adverse event ; Acellular pertussis vaccine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Background: Hypotonic-hyporesponsive episodes are rare side effects which may occur in infants within a few hours after immunization with diphtheria-tetanus-toxoid (DT) or diphtheria-tetanus-pertussis (DTP) vaccine. The patients appear in a shock-like condition, become pale, limp and unresponsive. This condition lasts for minutes to hours before the infants appear normal again. No sequelae have been reported. The etiology of this phenomenon is unknown. Case: A healthy 5 month old boy experienced a first hypotonic-hyporesponsive episode 3 hours after having received his second DTP(acellular)-Hib combined immunization along with a second dose of hepatitis B vaccine. One month later he received a third dose of the same DTPa-Hib vaccine and oral Polio and again a hypotonic-hyporesponsive episode occurred. The boy’s further development was normal, no sequelae have been observed. Discussion: The purpose of our report is to remind physicians of the rare possibility of a shock-like reaction after DT- or DTP immunization in infancy, which has also been observed in association with the use of the new acellular pertussis component vaccines – although less frequently than after conventional whole cell pertussis component vaccines. Furthermore, this is to our best knowledge the first report of a recurrent hypotonic-hyporesponsive episode and it suggests a predisposition for this reaction in our patient.
    Notes: Zusammenfassung Hintergrund: Hypoton-hyporesponsive Episoden treten als seltene Begleiterscheinung binnen weniger Stunden nach Diphtherie-Tetanus- (DT-) oder Diphtherie-Tetanus-Pertussis-Impfung (DPT-Impfungen) im Säuglingsalter auf. Sie sind durch einen schockartigen Zustand mit Blässe der Haut, reduziertem Muskeltonus und Apathie gekennzeichnet, der Minuten bis Stunden anhält, ehe eine plötzliche Normalisierung mit Restitutio ad integrum eintritt. Die Ursache ist ungeklärt. Fall: Ein unauffällig entwickelter männlicher Säugling zeigte im Alter von 5 Monaten nach der 2. DTPa-Hib-Kombinationsimpfung (mit azellulärer Pertussiskomponente) eine erste hypoton-hyporesponsive Episode. Bei der 3. DTPa-Hib-Immunisierung 1 Monat später kam es erneut zu einer hypoton-hyporesposiven Episode. Beide Episoden blieben ohne Folge, der Junge entwickelte sich weiterhin völlig normal. Diskussion: Unsere Mitteilung soll an die seltene Begleiterscheinung einer schockähnlichen Reaktion nach DT- bzw. DPT-Impfung im Säuglingsalter erinnern. Sie wird auch bei den neuen, sehr gut verträglichen azellulären Pertussisvakzinen beobachtet, wenn auch offenbar seltener als nach DPT-Impfung mit den herkömmlichen Ganzkeimvakzinen. Das hier erstmals berichtete wiederholte Auftreten einer solchen Reaktion läßt bei unserem Patienten an eine individuelle Disposition denken.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    The chemical educator 3 (1998), S. 1-11 
    ISSN: 1430-4171
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract An undergraduate instrumental analysis laboratory exercise is presented for the characterization of light emission generated using electrochemiluminescence (ECL). ECL involves the electrochemical generation of excited states and as such is a sensitive probe of electrochemical, electron-transfer and energy-transfer processes at electrified interfaces. An objective of this experiment is to have students develop an understanding of the mechanisms and factors affecting ECL. Also, this exercise gives students experience in coupling two powerful analytical techniques: electrochemistry and spectroscopy. With the recent development of ECL technology for use in clinical diagnostics applications, this exercise also facilitates discussions on the importance of basic research and the practical aspects of taking a technology from the bench top to commercial reality.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Insectes sociaux 46 (1999), S. 131-136 
    ISSN: 1420-9098
    Keywords: Key words:Vespula, Polistes, Vespidae, foraging, resource choice.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary: The role of visual cues provided by resident wasps on resource choice by yellowjacket and paper wasp foragers was investigated. Large spring queen yellowjackets and small early season yellowjacket foragers (Vespula germanica, Vespula maculifrons, and Vespula vidua) were extracted in hexane to remove odors and posed as though feeding at petri dish feeders bearing daisy-like flower models, equipped with microcapillary feeding tubes, and containing 1:3 honey:water solution. An array of five feeders was presented to foragers at a suburban and a woodland site in Saratoga Springs, New York. The visual cues provided by resident wasps influenced resource choice by approaching social wasp foragers. Vespula germanica, an introduced yellowjacket species that tends to dominate at rich resources, was the only wasp visiting the suburban feeders. Foragers of this species preferentially fed on feeders and flowers with posed wasps and fed most often next to large wasps. Polistes fuscatus foragers at the woodland site similarly preferred to feed on occupied feeders and flowers. Vespula maculifrons and V. consobrina preferentially visited unoccupied feeders. Individual V. maculifrons, V. consobrina and V. vidua foragers that landed on occupied feeders all preferentially visited unoccupied flowers on those feeders. Vespula vidua and V. flavopilosa foragers did not demonstrate a feeder preference based on the presence/absence of posed wasps. Vespula consobrina foragers that visited occupied feeders preferred those occupied by extracted V. maculifrons queens and workers; no other wasps showed species based landing preferences.
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