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21.
Hansen P.B. Raybon G. Koren U. Miller B.I. Young M.G. Newkirk M.A. Chien M.-D. Tell B. Burrus C.A. 《Electronics letters》1993,29(7):639-640
An electroabsorption modulator has been monolithically integrated with an extended-cavity laser, which incorporates a Bragg reflector. Actively modelocked at the fundamental cavity resonance frequency of 4.5 GHz, the laser provides a train of 6.3 ps pulses with a centre wavelength of 1544 nm onto which data is encoded by the modulator. This 4.5 Gbit/s single-chip transmitter is suitable for systems employing short optical pulses.<> 相似文献
22.
E. Coduro und E. Tell 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1968,138(2):112-126
Ohne Zusammenfassung 相似文献
23.
24.
Torphammar P. Tell R. Eklund H. Johnston A. 《Quantum Electronics, IEEE Journal of》1979,15(11):1271-1276
This paper deals with analytical and experimental work related to modulation of a semiconductor laser used in high bit rate communication. The approach is based upon minimizing the charge storage effect by a proper choice of the area of the modulating pulses and the bias current. The concept of using additional current pulses to probe for variations in electron density between pulses is investigated. The primary limitation on bit rate is found to be the ability to generate laser drive pulses free of ringing or similar transients. This and the 300 ps pulsewidth, an experimental constraint, limit the bit rate to about 1 Gbit/s. However, by using this approach it appears that bit rates considerably higher than 2 Gbits/s could be reached with sufficiently accurate control of drive pulse shape. It is found that the laser bias and the current pulse area had to be controlled within 1 percent and 10 percent, respectively. 相似文献
25.
K. Millies E. Renner und E. Tell 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1971,146(3):155-156
Ohne Zusammenfassung 相似文献
26.
Mittal Vijay A.; Tessner Kevin D.; Trottman Hanan D.; Esterberg Michelle; Dhruv Shivali H.; Simeonova Diana I.; McMillan Amanda L.; Murphy Erin; Saczawa Mary E.; Walker Elaine F. 《Canadian Metallurgical Quarterly》2007,116(2):260
The link between movement abnormalities and psychotic disorders is presumed to reflect common neural mechanisms that influence both motor functions and vulnerability to psychosis. The prodromal period leading to psychotic disorders represents both a viable point for intervention and a developmental period that, if studied, could shed light on etiology; however, no published studies have examined the temporal progression of this link. A group with high levels of prodromal symptomatology (i.e., adolescents with schizotypal personality disorder [SPD]; n = 42) and both psychiatric controls (with other personality disorders or conduct disorder [OD]; n = 30) and nonpsychiatric controls ([NC]; n = 49) were recruited. Videotapes of structured psychiatric interviews were coded for movement abnormalities by raters blind to participants' diagnostic status, and follow-up assessments were conducted 1 year later. Controlling for psychotropic medications, the authors found that adolescents with SPD exhibited significantly more motor abnormalities in the face and upper body than did OD and NC controls. At baseline, movement abnormalities were positively correlated with the severity of positive, negative, and total prodromal symptoms. Within the SPD group, baseline movement abnormalities predicted symptom severity 1 year later. Movement abnormalities represent an early risk indicator that may be predictive of later symptom severity and potentially of psychosis onset. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
27.
James D. Gilardi Sean S. Duffey Charles A. Munn Lisa A. Tell 《Journal of chemical ecology》1999,25(4):897-922
This study tests hypotheses on the biochemical functions of geophagy in parrots: mechanical enhancement of digestion, acid buffering capacity, mineral supplementation, adsorption of dietary toxins, and gastrointestinal cytoprotection. Parrots showed clear preferences for specific soil horizons. Comparisons of preferred and nonpreferred soils from several sites suggest that soils have little ability to enhance grinding and no measurable ability to buffer gastric pH. Soils offered insignificant mineral supplementation since most minerals occurred at similar levels in samples regardless of preference, and the minerals were generally more plentiful in the birds' diets. Sodium was available in moderate levels at some sites (>1000 ppm), but was well below sodium detection thresholds of parrots. X-ray diffraction, cation exchange capacity, and in vitro adsorptive trials showed that the preferred soils are capable of exchanging substantial quantities of cations and are capable of adsorbing low-molecular-weight secondary compounds. In captive Amazona parrots, orally administered clay reduced the bioavailability of the alkaloid quinidine by roughly 60%, demonstrating that in vivo adsorption of potentially toxic compounds may be a biologically important function of geophagy. Labeled clay remained in the lower gastrointestinal tract of captive parrots for >12 hr, which along with high adsorptive capacities, further suggests a potential role in protecting the gastrointestinal lining from various biological and chemical insults. Detoxification and cytoprotection are the most likely functions of geophagy for parrots and herbivores with similar ecologies. Given the variety of chemically defended seeds consumed by these herbivores, geophagy likely protects consumers from dietary toxins, allowing increased diet breadth and/or enhancing digestibility. 相似文献
28.
C. C. Aydiner E. Ü:Ustü:UndaG J. C. Hanan 《Metallurgical and Materials Transactions A》2001,32(11):2709-2715
The viscoelastic nature of bulk metallic glasses (BMGs), their low thermal conductivity, and the fast cooling used in their
processing subject them to thermal tempering. This process leads to a residual stress state in which compression on the surface is balanced by tension in the interior.
For the first time, we have calculated such stresses in metallic glasses by adapting an analytical instant-freezing model
previously developed for silicate glasses. This model has been demonstrated to be reasonably accurate in predicting the final
residual stresses, although, due to its very nature, it neglects transient effects. For an infinite plate geometry and employing
processing parameters often used for metallic glasses, we predict that significant residual stresses can be generated in these
materials during thermal tempering. Preliminary measurements conducted using the layer-removal method yield compressive residual
stress values close to model predictions. 相似文献
29.
Branch and bound algorithms for Mixed-Integer Linear Programming (MILP) almost universally branch on a single variable to create disjunctions. General linear expressions involving multiple variables are another option for branching disjunctions, but are not used for two main reasons: (i) descendent LPs tend to solve more slowly because of the added constraints, so the overall solution time is increased, and (ii) it is difficult to quickly find an effective general disjunction. We study the use of general disjunctions to reach the first MILP-feasible solution quickly, showing for the first time that general disjunctions can provide speed improvements for hard MILP models. The speed-up is due to new and efficient ways to (i) trigger the inclusion of a general disjunction only when it is likely to be beneficial, and (ii) construct effective general disjunctions very quickly. Our empirical results show performance improvements versus a state of the art commercial MILP solver. 相似文献
30.
E. Coduro und E. Tell 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1989,189(2):G25-G40
Ohne Zusammenfassung
Einschließlich amtlicher Verlautbarungen, Richtlinien von Verbänden u. dgl. 相似文献
Laws and statutes
Einschließlich amtlicher Verlautbarungen, Richtlinien von Verbänden u. dgl. 相似文献