scholarly journals Long-range and long-term interferometric tracking by static and dynamic force-clamp optical tweezers

2011 ◽  
Vol 19 (23) ◽  
pp. 22364 ◽  
Author(s):  
A. Guiggiani ◽  
B. Torre ◽  
A. Contestabile ◽  
F. Benfenati ◽  
M. Basso ◽  
...  
Keyword(s):  
Long Range ◽  
Optical Tweezers ◽  
Dynamic Force ◽  
Force Clamp

scholarly journals Dual-trap optical tweezers with real-time force clamp control

2011 ◽  
Vol 82 (8) ◽  
pp. 083102 ◽  
Author(s):  
Anders E. Wallin ◽  
Heikki Ojala ◽  
Gabija Ziedaite ◽  
Edward Hæggström
Keyword(s):  
Real Time ◽  
Optical Tweezers ◽  
Force Clamp

scholarly journals Anthropogenic Effects on Forest Ecosystems at Various Spatio-Temporal Scales

2002 ◽  
Vol 2 ◽  
pp. 827-841 ◽  
Author(s):  
Michael Bredemeier
Keyword(s):  
Air Pollution ◽  
Long Range ◽  
Acid Deposition ◽  
Soil Degradation ◽  
Forest Ecosystems ◽  
Global Scale ◽  
Soil Productivity ◽  
Long Term Effects ◽  
The World

The focus in this review of long-term effects on forest ecosystems is on human impact. As a classification of this differentiated and complex matter, three domains of long-term effects with different scales in space and time are distinguished: 1- Exploitation and conversion history of forests in areas of extended human settlement 2- Long-range air pollution and acid deposition in industrialized regions 3- Current global loss of forests and soil degradation.There is an evident link between the first and the third point in the list. Cultivation of primary forestland — with its tremendous effects on land cover — took place in Europe many centuries ago and continued for centuries. Deforestation today is a phenomenon predominantly observed in the developing countries, yet it threatens biotic and soil resources on a global scale. Acidification of forest soils caused by long-range air pollution from anthropogenic emission sources is a regional to continental problem in industrialized parts of the world. As a result of emission reduction legislation, atmospheric acid deposition is currently on the retreat in the richer industrialized regions (e.g., Europe, U.S., Japan); however, because many other regions of the world are at present rapidly developing their polluting industries (e.g., China and India), “acid rain” will most probably remain a serious ecological problem on regional scales. It is believed to have caused considerable destabilization of forest ecosystems, adding to the strong structural and biogeochemical impacts resulting from exploitation history.Deforestation and soil degradation cause the most pressing ecological problems for the time being, at least on the global scale. In many of those regions where loss of forests and soils is now high, it may be extremely difficult or impossible to restore forest ecosystems and soil productivity. Moreover, the driving forces, which are predominantly of a demographic and socioeconomic nature, do not yet seem to be lessening in strength. It can only be hoped that a wise policy of international cooperation and shared aims can cope with this problem in the future.

Power-law correlations, related models for long-range dependence and their simulation

2000 ◽  
Vol 37 (04) ◽  
pp. 1104-1109 ◽  
Author(s):  
Tilmann Gneiting
Keyword(s):  
Long Range ◽  
Power Law ◽  
Long Memory ◽  
Stationary Time Series ◽  
Long Range Dependence ◽  
Short Term ◽  
Permissible Range ◽  
Simultaneous Fitting ◽  
Straightforward Proof

Martin and Walker ((1997) J. Appl. Prob. 34, 657–670) proposed the power-law ρ(v) = c|v|-β, |v| ≥ 1, as a correlation model for stationary time series with long-memory dependence. A straightforward proof of their conjecture on the permissible range of c is given, and various other models for long-range dependence are discussed. In particular, the Cauchy family ρ(v) = (1 + |v/c|α)-β/α allows for the simultaneous fitting of both the long-term and short-term correlation structure within a simple analytical model. The note closes with hints at the fast and exact simulation of fractional Gaussian noise and related processes.

scholarly journals Parametrisation of the orographic enhancement of precipitation and deposition in a long-term, long-range transport model

2000 ◽  
Vol 18 (11) ◽  
pp. 1447-1466 ◽  
Author(s):  
D. S. Lee ◽  
R. D. Kingdon ◽  
J. A. Garland ◽  
B. M. R. Jones
Keyword(s):  
Sulfur Dioxide ◽  
Long Range ◽  
Wet Deposition ◽  
Enhancement Factor ◽  
Long Range Transport ◽  
Orographic Precipitation ◽  
Range Transport ◽  
Orographic Enhancement ◽  
The Uk

Abstract. Orographic enhancement of wet deposition arising from the 'seeder-feeder' effect is, by necessity, highly parametrised in long-range transport models of acid deposition that are long-term (i.e. annual average) and spatially resolved at tens of kilometres. Here, we describe a mechanistic approach to the incorporation of these mechanisms into such a model. The model formulation required the following: precipitation rate by direction and quantification of the fractions that are orographic and non-orographic; treatment of the fast oxidation of sulfur dioxide in clouds; the directionality of the seeder-feeder process; and a quantitative basis for increasing wet deposition factors to account for the seeder-feeder process. The directionality of non-orographic precipitation was determined from meteorological data at 47 sites across the UK. Orographic precipitation varies on a much finer scale than can be interpolated from measurements, and thus a modelling approach was adopted. The directionality of the seeder-feeder effect was taken from measurements. The enhancement factor of the orographic component of precipitation, assumed to represent feeder-rain, was determined from a review of measurements. Fast oxidation of sulfur dioxide is an observed phenomenon in cap-cloud, but limited in duration. An adjustment was made to the sulfur dioxide oxidation rate in the model in locations where cap-cloud was assumed to be present. The results from the model were compared with UK deposition budgets and enhanced wet deposition maps. The revised parametrisation underestimated the UK wet deposition budgets of oxidised N and S, but spatial patterns of deposition were improved for much of the UK. It was concluded that this was a satisfactory outcome given the constraints of the statistical approach of weighting of deposition at receptors utilising straight line trajectories. The sensitivity of the model to directional constraints of seeder-feeder enhancement was tested and it was concluded that a fairly narrow constraint resulted in similar estimations to a broader one, and the broader constraint was thus adopted as frontal conditions which result in the process arrive from a fairly broad band of directions. When enhancement was allowed to occur from all directions, UK wet deposition of oxidised N and S was increased by 10%. The sensitivity to the enhancement factor on wet deposition was tested and found to be relatively robust. An increase in the enhancement factor from 2 to 6 resulted in increases in UK wet deposition of oxidised N and S of 9 and 6%, respectively.Key words: Atmospheric composition and structure (pollution – urban and regional) – Meteorology and atmospheric dynamics (precipitation)

Carbon Dioxide and the Environment: A Problem of Uncertainty

1985 ◽  
Vol 28 (2) ◽  
pp. 60-66
Author(s):  
John Lemons
Keyword(s):  
Carbon Dioxide ◽  
Adverse Effects ◽  
Carbon Cycle ◽  
Long Range ◽  
Scientific Knowledge ◽  
Fossil Fuels ◽  
Energy Use ◽  
Future Generations ◽  
Remedial Action

The combustion of fossil fuels increases atmospheric levels of carbon dioxide. This may cause a long-term warming of the atmosphere. Solutions to the carbon dioxide problem are particularly difficult because adverse effects will be felt by future generations, but remedial action and sacrifices must be made by present generations. Decisions regarding the problem which affect both the immediate and long-range future must be made deliberately or by default in perhaps only 15-20 years, before we are reasonably confident with our knowledge of the problem and before we know whether it will, in fact, occur. Much of the uncertainty involves projections of future energy use, and scientific knowledge of the carbon cycle and the environment.

MODELING NETWORK TRAFFIC USING CAUCHY CORRELATION MODEL WITH LONG-RANGE DEPENDENCE

2005 ◽  
Vol 19 (17) ◽  
pp. 829-840 ◽  
Author(s):  
MING LI ◽  
S. C. LIM
Keyword(s):  
Long Range ◽  
Network Traffic ◽  
Traffic Engineering ◽  
Single Parameter ◽  
Traffic Modeling ◽  
Long Range Dependence ◽  
Correlation Model ◽  
Traffic Time Series ◽  
Fractal Properties

Much attention has been given to the long-range dependence and fractal properties in network traffic engineering, and these properties are also widely observed in many fields of science and technologies. Traffic time series is conventionally characterized by its fractal dimension D, which is a measure for roughness, and by the Hurst parameter H, which is a measure for long-range dependence, see for examples (Refs. 10–12). Each property has been traditionally modeled and explained by self-affine random functions, such as fractional Gaussian noise (FGN)1,10–13,18,22–28 and fractional Brownian motion (FBM),6,7 where a linear relationship between D and H, say D = 2 - H for one-dimensional series, links the two properties. The limitation of single parameter models (e.g., FGN) in long-range dependent (LRD) traffic modeling has been noticed as can be seen from Refs. 1, 18 and 25. Hence, models which can provide good fitting of LRD traffic for both short-term lags and long-term ones are worth studying due to the importance of accurate models of traffic in network communications.13 This letter utilizes a statistical model called the Cauchy correlation model to model LRD traffic. This model characterizes D and H separately, and it allows any combination of two within the constraint of LRD condition. It is a new power-law correlation model for LRD traffic modeling with its local and global behavior decoupling. Its flexibility in data modeling in comparison with a single parameter model of FGN is briefly discussed, and applications to LRD traffic modeling demonstrated.

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