Interaction of atomic wave packets with four-wave mixing: detection of rubidium and potassium wave packets by coherent ultraviolet emission

The observation of an atomic wave packet by use of a coherent, nonlinear-optical process is reported. Wave packets formed in K or Rb vapor by two-photon excitation of ns and (n-2)dstates (n=8 for K; n=11 , 12 for Rb) with red (~620-nm) , 80-100-fs pulses were detected by four-wave mixing in pump-probe experiments. The temporal behavior of the wave packet is observed by monitoring the coherent UV radiation generated near the alkali mp(2)P? (2)S(1/2) (7相似文献   

The impact of disruption and delay when compressing large projects: going for incentives?

Demands by clients for earlier delivery after a project has started are increasing. This paper investigates the consequential disruption and delay that follows from the contractor accepting these demands. Explorations are carried out using a System Dynamics model based upon a large model constructed to represent the complexity of a claim for disruption and delay in relation to a specific mega-project. The model used for the explorations has been validated further using information gathered during work on other claim projects. The model enables the impact of disruption and delay resulting from the holistic and dynamic impact of a compressed delivery date to be assessed in relation to two specific and typical options. Use of the model suggests that the probability seems slight of finding the highly specific circumstances where there is any certainty in an outcome of early delivery at little extra cost.     

Building addressable libraries: site selective coumarin synthesis and the "real-time" signaling of antibody-coumarin binding

[reaction: see text] The feasibility of using active semiconductor chips containing addressable arrays of microelectrodes for the "real-time" monitoring of biologically relevant binding events has been demonstrated by detecting the binding of a coumarin substrate by an anticoumarin antibody. The coumarin substrate was synthesized proximal to predetermined electrodes on the chip with the use of a Pd(II) reagent that was itself generated by using the selected electrodes. Once the coumarin was synthesized, its binding to the anticoumarin antibody was detected by monitoring the current associated with a ferrocene-ferrocinium ion redox cycle that was established between the electrodes on the chip and a remote auxiliary electrode.     

On global behavior of solutions to an inverse problem for nonlinear parabolic equations

We find conditions on data guaranteeing global nonexistence of solutions to an inverse source problem for a class of nonlinear parabolic equations. We also establish a stability result on a bounded domain for a problem with the opposite sign on the power type nonlinearity.     

Absolute Quantitation of Glycosylation Site Occupancy Using Isotopically Labeled Standards and LC-MS

N-linked glycans are required to maintain appropriate biological functions on proteins. Underglycosylation leads to many diseases in plants and animals; therefore, characterizing the extent of glycosylation on proteins is an important step in understanding, diagnosing, and treating diseases. To determine the glycosylation site occupancy, protein N-glycosidase F (PNGase F) is typically used to detach the glycan from the protein, during which the formerly glycosylated asparagine undergoes deamidation to become an aspartic acid. By comparing the abundance of the resulting peptide containing aspartic acid against the one containing non-glycosylated asparagine, the glycosylation site occupancy can be evaluated. However, this approach can give inaccurate results when spontaneous chemical deamidation of the non-glycosylated asparagine occurs. To overcome this limitation, we developed a new method to measure the glycosylation site occupancy that does not rely on converting glycosylated peptides to their deglycosylated forms. Specifically, the overall protein concentration and the non-glycosylated portion of the protein are quantified simultaneously by using heavy isotope-labeled internal standards coupled with LC-MS analysis, and the extent of site occupancy is accurately determined. The efficacy of the method was demonstrated by quantifying the occupancy of a glycosylation site on bovine fetuin. The developed method is the first work that measures the glycosylation site occupancy without using PNGase F, and it can be done in parallel with glycopeptide analysis because the glycan remains intact throughout the workflow.

The role of feedback dynamics in disruption and delay on the nature of disruption and delay (D&D) in major projects

The idea that small disruptions and delays can cause serious consequences to the life of a major project, well beyond that which might be easily attributed to their direct impact, is well established. Nevertheless, the nature of this ‘delay and disruption’ is still not fully understood. This paper discusses some of the issues and difficulties in gaining a full understanding. In particular it presents the variety of ways in which disruptions occur, and the variety of consequences that may unfold. It also focuses attention on a number of issues that arise when ‘normal’ methods of analysis of complex projects might be used, for example, the analysis and costing of change orders and the use of network analysis. The role of dynamic feedback and the ‘portfolio effect’ is introduced, particularly with reference to project acceleration and changing productivity.     

Functional MnO nanoclusters for efficient siRNA delivery

A non-viral gene delivery nanovehicle based on Alkyl-PEI2k capped MnO nanoclusters was synthesized via a simple, facile method and used for efficient siRNA delivery and magnetic resonance imaging.