scholarly journals The Detection of Time-correlated Photons by a Coincidence Counter

1959 ◽  
Vol 12 (1) ◽  
pp. 77 ◽  
Author(s):  
RQ Twiss ◽  
AG Little
Keyword(s):  
Light Source ◽  
Reasonable Agreement ◽  
Plasma Oscillations ◽  
Arrival Times ◽  
Degree Of Coherence ◽  
Significant Difference ◽  
Coincidence Counter ◽  
Spurious Effect ◽  
Light Beams ◽  
Theory And Experiment

The existence of a correlation between the arrival times of photons has been confirmed by measurements with a coincidence counter having a resolving time of 3�5 X 10-9 sec in three different experiments. In the first experiment it was found that the number of coincidence counts recorded from two photomultipliers, the apertures of which were optically superimposed, was significantly greater than when the light beams were incoherent. Furthermore, the number of these correlated counts was in satisfactory agreement with that predicted by theory. In the second experiment the change in the number of excess coincidences was measured as the degree of coherence of the light was altered by increasing the apparent separation of the photocathodes, and in this case also there was reasonable agreement between theory and experiment. In the final experiment it was shown that there was a significant difference between the number of coincidences observed when the light beams were in identical as opposed to orthogonal polarizations, and this last result especially makes it extremely improbable that the correlation could be caused by some spurious effect, such as plasma oscillations in the source, since the light source itself was found to be completely unpolarized.

Membrane thickening of water works sludge

2001 ◽  
Vol 1 (5-6) ◽  
pp. 215-220
Author(s):  
A. Gillighan ◽  
S.J. Judd ◽  
R. Eyres
Keyword(s):  
Hydraulic Resistance ◽  
Reasonable Agreement ◽  
Chemical Cleaning ◽  
Solids Concentration ◽  
Significant Difference ◽  
Layer Resistance ◽  
Tubular Membranes ◽  
Resistance Data ◽  
Mechanical Cleaning ◽  
Dynamic Layer

The efficacy of ultrafiltration (UF) and microfiltration (MF) membranes was assessed for the concentration of actual waterworks sludges using crossflow tubular membranes operated at constant trans-membrane pressure. The MF membrane gave higher initial fluxes than the UF membrane but after 10 min of filtration the flux value and its decline tended to be very similar for both membranes operating under the same conditions. All membranes gave permeate product water of <0.2 NTU and <100ppb coagulant at all times. For both membranes mechanical cleaning, with sponge balls, was at least as effective as acid chemical cleaning, indicating that no significant permanent internal fouling occurred for these membrane materials. Hydraulic resistance data indicated a significant difference in the dynamic layer resistance between the two membranes. Whilst the UF membrane had a hydraulic resistance 3.7 times that of the MF membrane, the dynamic layer formed on the UF membrane during operation displayed a maximum hydraulic resistance almost nine times lower than that of the MF membrane operating under the same conditions. Correlation of cake resistance R versus feed solids concentration C for all the data generated for t>0 demonstrated reasonable agreement with the expression R∝ca where a=0.37 in the current study. This trend has been recorded in previous reported studies, a varying between 0.33 and 0.62 depending on sludge dewaterability.

Unbalance Response of a Dual Rotor System: Theory and Experiment

1993 ◽  
Vol 115 (4) ◽  
pp. 427-435 ◽  
Author(s):  
K. Gupta ◽  
K. D. Gupta ◽  
K. Athre
Keyword(s):  
System Theory ◽  
Transfer Matrix ◽  
Mode Shape ◽  
Reasonable Agreement ◽  
Complex Variables ◽  
Rotor System ◽  
Experimental Results ◽  
Unbalance Response ◽  
Theoretical Results ◽  
Theory And Experiment

A dual rotor rig is developed and is briefly discussed. The rig is capable of simulating dynamically the two spool aeroengine, though it does not physically resemble the actual aeroengine configuration. Critical speeds, mode shape, and unbalance response are determined experimentally. An extended transfer matrix procedure in complex variables is developed for obtaining unbalance response of dual rotor system. Experimental results obtained are compared with theoretical results and are found to be in reasonable agreement.

Feed intake of grazing cattle. IV. A study with milk cows of the influence of pasture restriction combined with supplementary feeding on production per animal and per acre

1966 ◽  
Vol 8 (1) ◽  
pp. 47-57 ◽  
Author(s):  
W. Holmes ◽  
J. G. W. Jones ◽  
C. Adeline
Keyword(s):  
Feed Intake ◽  
Reasonable Agreement ◽  
Close Agreement ◽  
Live Weight ◽  
Grazing Cattle ◽  
Electric Fence ◽  
Significant Difference ◽  
Milk Cows ◽  
Index Methods ◽  
Pasture Area

The possibility that restriction of pasture and controlled supplementation of the diet of milking cows with concentrates might improve the efficiency of utilisation of grazing was examined in a double reversal grazing experiment with 9 Ayrshire cows per treatment which extended over 4 months.Cows received either pasture alone allocated daily by electric fence (treatment B), or half the pasture area plus one-third of their expected DOM intake offered as concentrates (treatment A).In the first two periods, treatment A resulted in closer defoliation of the pasture.Over the whole experiment there was no significant difference in yield of fat-corrected milk between treatments, although treatment A depressed butterfat percentage and raised milk yield significantly. Treatments did not influence live-weight gain significantly and toth groups gained over the season.Feed intake estimated by chromic oxide-faecal index methods was similar for both treatments except in period 1. Intake estimates by clipping methods or by faecal index methods were in close agreement in period 1 for treatment B and in reasonable agreement in periods 2 and 3.The results are discussed particularly with a view to the possibilities of replacing some grazing with barley or other concentrated feeds. On the available evidence this is economically feasible only where very profitable uses of the grassland saved are possible.

scholarly journals Improved Seismic Monitoring with OBS Deployment in the Arctic: A Pilot Study from Offshore Western Svalbard

2021 ◽  
Author(s):  
Zeinab Jeddi ◽  
Lars Ottemöller ◽  
Mathilde Sørensen ◽  
Sara Rezaei ◽  
Steven Gibbons ◽  
...  
Keyword(s):  
Waveform Inversion ◽  
Arctic Region ◽  
The Arctic ◽  
Spreading Ridge ◽  
Ocean Bottom ◽  
Low Velocity ◽  
Arrival Times ◽  
Regional Seismicity ◽  
Velocity Anomaly ◽  
Significant Difference

The mid-ocean ridge system is the main source of earthquakes within the Arctic region. The earthquakes are recorded on the permanent land-based stations in the region, although smaller earthquakes remain undetected. In this study, we make use of three Ocean Bottom Seismographs (OBSs) that were deployed offshore western Svalbard, along the spreading ridges. The OBS arrival times were used to relocate the regional seismicity using a Bayesian approach, which resulted in a significant improvement with tighter clustering around the spreading ridge. We also extended the regional magnitude scales for the northern Atlantic region for OBSs by computing site correction terms. Besides location and magnitude improvement, the OBS network was able to detect hundreds of earthquakes, mostly with magnitude below Mw=3, including a swarm activity at the Molloy Deep. Our offshore observations provide further evidence of a low velocity anomaly offshore Svalbard, at the northern tip of Knipovich ridge, that was previously seen in full waveform inversion. We conclude that even a single permanent OBS near the ridge would make a significant difference to earthquake catalogs and their interpretation.

scholarly journals Improved Seismic Monitoring with OBS Deployment in the Arctic: A Pilot Study from Offshore Western Svalbard

2021 ◽  
Author(s):  
Zeinab Jeddi ◽  
Lars Ottemöller ◽  
Mathilde B. Sørensen ◽  
Sara Rezaei ◽  
Steven J. Gibbons ◽  
...  
Keyword(s):  
Waveform Inversion ◽  
Arctic Region ◽  
The Arctic ◽  
Spreading Ridge ◽  
Ocean Bottom ◽  
Low Velocity ◽  
Arrival Times ◽  
Regional Seismicity ◽  
Velocity Anomaly ◽  
Significant Difference

Abstract The mid-ocean ridge system is the main source of earthquakes within the Arctic region. The earthquakes are recorded on the permanent land-based stations in the region, although, smaller earthquakes remain undetected. In this study, we make use of three Ocean Bottom Seismographs (OBSs) that were deployed offshore western Svalbard, along the spreading ridges. The OBS arrival times were used to relocate the regional seismicity, using a Bayesian approach, which resulted in a significant improvement with tighter clustering around the spreading ridge. We also extended the regional magnitude scales for the northern Atlantic region for OBSs, by computing site correction terms. Besides location and magnitude improvement, the OBS network was able to detect hundreds of earthquakes, mostly with magnitude below Mw 3, including a swarm activity at the Molloy Deep. Our offshore observations provide further evidence of a low-velocity anomaly offshore Svalbard, at the northern tip of Knipovich ridge that was previously seen in full-waveform inversion. We conclude that even a single permanent OBS near the ridge would make a significant difference to earthquake catalogs and their interpretation.

Comparison of Patients' Assessments on Overall Facial Rejuvenation and Procedural Pain Seen with a Fluorescent Pulsed-Light Source and Those Seen with a Traditional Intense Pulsed-Light Source

2005 ◽  
Vol 22 (2) ◽  
pp. 119-122
Author(s):  
Walter K. Nahm ◽  
Lisa K. Chipps ◽  
David A. Wrone ◽  
Fangchao Ma ◽  
David A. Lee ◽  
...  
Keyword(s):  
Light Source ◽  
Facial Rejuvenation ◽  
Intense Pulsed Light ◽  
Procedural Pain ◽  
Rank Test ◽  
Light Sources ◽  
Pulsed Light ◽  
Paired Data ◽  
Photodamaged Skin ◽  
Significant Difference

Introduction: Intense pulsed-light (IPL) treatments are effective alternatives to ablative procedures for improving the appearance of photodamaged skin. Currently, there are multiple IPL sources to modulate photoaged skin, but there are no studies comparing the efficacy of or pain associated with 2 different PL sources. Therefore, we chose to compare patients' assessments of overall cutaneous rejuvenation and pain associated with a fluorescent PL source and a traditional IPL source. Materials and Methods: We performed a retrospective analysis of 24 patients who were treated with both a fluorescent PL source and a traditional IPL source. These patients completed questionnaire surveys that assessed (by a graded scale) pain during the procedure and overall satisfaction with each IPL source. The Wilcoxon signed-rank test for paired data as well as McNemar's test were used to compare overall facial rejuvenation and procedural pain between the 2 light sources. Results: For both light sources, most patients reported “fair” or better improvement in skin appearance. The patients did not report a significant difference in overall skin improvement between the treatments with each light source. In addition, most patients did not report having pain during recovery after procedures by either light source. However, patients did report significantly less pain during treatments with the fluorescent device compared with the traditional IPL source. Discussion: IPL sources provide safe and effective nonablative treatment for facial photorejuvenation. Patients are equally satisfied with the effects seen with both traditional and fluorescent PL source, but reported less pain with the fluorescent PL procedure during treatments.

Coherence properties of entangled light beams generated by parametric down-conversion: Theory and experiment

1996 ◽  
Vol 53 (6) ◽  
pp. 4360-4371 ◽  
Author(s):  
Adel Joobeur ◽  
Bahaa E. A. Saleh ◽  
Todd S. Larchuk ◽  
Malvin C. Teich
Keyword(s):  
Parametric Down Conversion ◽  
Light Beams ◽  
Down Conversion ◽  
Theory And Experiment

NONEXTENSIVE STATISTICAL MECHANICS APPROACH TO THE SOMMERFELD MODEL FOR METALLIC ELEMENTS

2013 ◽  
Vol 27 (31) ◽  
pp. 1350181 ◽  
Author(s):  
KAMEL OURABAH ◽  
MOULOUD TRIBECHE
Keyword(s):  
Heat Capacity ◽  
Statistical Mechanics ◽  
Reasonable Agreement ◽  
Chemical Potential ◽  
Metallic Elements ◽  
Nonextensive Statistical Mechanics ◽  
Usual Model ◽  
Dirac Distribution ◽  
Entropic Index ◽  
Theory And Experiment

Using the generalized Fermi–Dirac distribution function arising from Tsallis statistical mechanics, we revisit the Sommerfeld model for metallic elements. The chemical potential, the total energy and the heat capacity are calculated. It is shown that the linearity between the heat capacity and the temperature is q-dependent, where q stands for the entropic index. In the limit q→1, the results of the usual model are recovered. Comparisons are made with experimental data and with the values of the usual model. The Pauli magnetic susceptibility is found not affected by the electron nonextensivity. Our results suggest that we can rely on the generalized nonextensive Sommerfeld model to expect achievement of reasonable agreement between theory and experiment. They may aid to constrain the values of the nonextensive parameter q for metallic elements and to determine more clearly the reality of nonextensive effects.

RELATION BETWEEN LIGHT SOURCE AND GROWTH OF BROILER CHICKENS

1974 ◽  
Vol 54 (4) ◽  
pp. 687-691 ◽  
Author(s):  
J. F. HURNIK ◽  
W. D. MORRISON ◽  
R. G. BROWN
Keyword(s):  
Light Source ◽  
Broiler Chickens ◽  
Spectral Composition ◽  
The Body ◽  
Fluorescent Light ◽  
Broiler Chicks ◽  
Ambulatory Activity ◽  
Visual Appearance ◽  
Significant Difference ◽  
Body Weights

Four hundred and forty vent-sexed commercial broiler chicks were used in this study. One half of this sample was exposed to common fluorescent light, the other half to a light source that in the spectral composition better approximates daylight characteristics (Vita-lite). Body weights of all birds were measured at weekly intervals. Weight of the body organs was measured on 20 birds randomly taken from each of four possible light source-sex combinations at 14-day intervals. The only significant difference in body weights linked with lighting was found in 2-wk-old chicks. High interactions between sex and lighting at this age revealed a positive effect of Vita-lite on females. In all other age categories, lighting did not affect body weights and did not interact with sex. Regression of body weights on age did not show any differentiation in growth related to the light source. Proportional weight of body organs did not indicate any significant effect of lighting. Birds in cages, illuminated with Vita-lite, when transferred to floor pens showed lower ambulatory activity than their counterparts from normal fluorescent light. Overall mortality during the first 14 days was lower in the Vita-lite group. Frequencies of subjective classifications of birds’ visual appearance showed evident sex × light source interactions only at the age of 14 days.

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