Energy transfer between chromophores in the reaction center of Rhodobacter sphaeroides R-26 with and without the initial donor oxidized and in reaction centers from the strain VR(L157) that has the mutation Val to Arg at L157 has been investigated using femtosecond transient absorption spectroscopy. Pigment extractions and an analysis of the ground-state absorbance spectrum indicate that VR(L157) reaction centers have a substantial reduction in the amount of bacteriochlorophyll present per reaction center, due to the loss of one or both of the bacteriochlorophylls in the initial electron donor (P). The QY transition bands of the bacteriochlorophyll monomers (B) and the bacteriopheophytins (H) in reaction centers from the three reaction center samples (R-26 with and without P oxidized and VR(L157)) were selectively excited using 150 fs duration, 5 nm bandwidth pulses, and transient absorbance spectra were recorded. Quenching of the lowest excited state of the bacteriochlorophyll monomer (B*) occurs in hundreds of femtoseconds in R-26 reaction centers either with or without P initially oxidized. Selective excitation of B in VR(L157) reaction centers results in a nanosecond lifetime B* excited state. Neither charge separation nor fast quenching of B* is observed in VR(L157) reaction centers, contrary to what one might expect from predictions of the energetics of B* relative to charge-separated states such as B+H-. The fluorescence spectrum of B* in this mutant is similar in width to the absorbance spectrum of B and is centered near 801 nm (the mutant's ground-state B band peaks at 796 nm). Picosecond fluorescence measurements of VR(L157) reaction centers show that fluorescence decay from B* is multiexponential and occurs on the order of nanoseconds. From these results, it is concluded that P is required for fast quenching of B but that the oxidation state of P does not strongly affect the quenching process. This suggests that spectral or orbital overlap between B and P does not limit the ultrafast rate of energy transfer between these two cofactors. One possibility is that nuclear motion limits the rate of energy transfer.

We introduce a graphene-based nanofluidic cell that facilitates in situ imaging of liquid samples via transmission electron microscopy. The cell combines the benefits of graphene liquid cellsnamely, high resolution, reduced charging effects, and excellent sample stabilitywith the ability to introduce reactants and control fluid concentrations as provided by conventional silicon-nitride-windowed flow cells. The graphene flow cell offers significantly less window bowing compared to existing commercial holders. We demonstrate the performance of the flow cell by imaging gold nanoparticle dynamics and uranyl acetate crystallization. Our results confirm the utility of graphene flow cells in obtaining the high spatial and temporal resolution required for probing the complex dynamics of nanoparticles and nucleation pathways in aqueous solutions.

Femtosecond transient absorbance spectra of quinone-depleted Rhodobacter sphaeroides R-26 reaction centers in the Q X transition region have been measured at 15 K under various excitation conditions. This study focuses on the excitation wavelength dependence and excitation intensity dependence of the formation of charge-separated states on the A- and B-side of the reaction center, judging from the bleaching of the 533 nm (B-side) and 544 nm (A-side) ground-state transitions of the reaction center bacteriopheophytins (HA and HB). Upon low-intensity selective excitation directly into the bacteriopheophytin Q Y transitions (near 760 nm), bleaching of both ground-state bacteriopheophytin Q X transitions (533 and 544 nm) appeared immediately, showing that initially either the A- or B-side bacteriopheophytin could be excited. However, both excited states ultimately resulted in P+HA - formation under these conditions. Low-intensity excitation at any of the various wavelengths (595, 750, 760, and 880 nm) showed no difference in the kinetics of the A-side charge separation forming P+HA - and no substantial formation of the B-side charge-separated state, P+HB -. In contrast, high-intensity 595 nm excitation resulted in substantial long-lived bleaching of the B-side bacteriopheophytin ground-state transition at 533 nm. This 533 nm bleaching was formed with essentially the same time constant as the bleaching at 544 nm due to A-side charge separation. Both bleaching bands persisted at the longest times measured (hundreds of picoseconds) in quinone-removed reaction centers. The long-lived bleaching at 533 nm using high-intensity excitation most likely represents the formation of P+HB - with a relative yield (percent of total charge separate state) of nearly 40%. One possible mechanism for B-side electron transfer is that two-photon excitation of the reaction center resulting in the state P*BB* makes P+BB - thermodynamically accessible.

Methods: This was a retrospective, time series analysis of 27 provider groups and managed care organizations from 1998 through 2006. Patients with hypertension were identified from more than 4000 physicians. Medical charts were collected and clinical data were evaluated using prevailing JNC criteria during the time period before and after JNC 7.Results: A total of 19,258 patients were identified with hypertension: 15,258 included in the before-JNC 7 cohort and 4,000 in the after-JNC 7 cohort. BP control in the before-JNC 7 cohort was 40.8% compared with 49.3% in the after-JNC 7 cohort (P < .0001). After controlling for demographic and clinical covariates, patients in the before-JNC 7 cohort were 45% less likely to achieve BP control compared with the after-JNC 7 cohort (odds ratio, 0.551; P < .0001). Conclusion

From insects to mice, oocytes develop within cysts alongside nurse-like sister germ cells. Prior to fertilization, the nurse cells’ cytoplasmic contents are transported into the oocyte, which grows as its sister cells regress and die. Although critical for fertility, the biological and physical mechanisms underlying this transport process are poorly understood. Here, we combined live imaging of germline cysts, genetic perturbations, and mathematical modeling to investigate the dynamics and mechanisms that enable directional and complete cytoplasmic transport in Drosophila melanogaster egg chambers. We discovered that during “nurse cell (NC) dumping” most cytoplasm is transported into the oocyte independently of changes in myosin-II contractility, with dynamics instead explained by an effective Young–Laplace law, suggesting hydraulic transport induced by baseline cell-surface tension. A minimal flow-network model inspired by the famous two-balloon experiment and motivated by genetic analysis of a myosin mutant correctly predicts the directionality, intercellular pattern, and time scale of transport. Long thought to trigger transport through “squeezing,” changes in actomyosin contractility are required only once NC volume has become comparable to nuclear volume, in the form of surface contractile waves that drive NC dumping to completion. Our work thus demonstrates how biological and physical mechanisms cooperate to enable a critical developmental process that, until now, was thought to be mainly biochemically regulated.

Recent advances in computer vision and inverse light transport theory have resulted in several non-line-of-sight imaging techniques. These techniques use photon time-of-flight information encoded in light after multiple, diffuse reflections to reconstruct a three-dimensional scene. In this paper, we propose and describe two iterative backprojection algorithms, the additive error backprojection (AEB) and multiplicative error backprojection (MEB), whose goal is to improve the reconstruction of the scene under investigation over non-iterative backprojection algorithms. We evaluate the proposed algorithms' performance applied to simulated and real data (gathered from an experimental setup where the system needs to reconstruct an unknown scene). Results show that the proposed iterative algorithms are able to provide better reconstruction than the unfiltered, non-iterative backprojection algorithm for both simulated and physical scenes, however are more sensitive to errors in the light transport model.

Almost one-third of patients initiating imatinib for CP-CML required dose modification, treatment interruption, or discontinuation. Opportunities for improved monitoring in this setting were identified. Limitations include those inherent to retrospective analyses based on EMR and the uncertain extrapolability of the results.

Patients receiving FC experienced fewer hospitalizations with the potential for significant savings.