General no-go condition for stochastic pumping.

The control of chemical dynamics requires understanding the effect of time-dependent transition rates between states of chemomechanical molecular configurations. Pumping refers to generating a net current, e.g., per period in the time dependence, through a cycle of consecutive states. The work of artificial machines or synthesized molecular motors depends on it. In this paper we give short and simple proofs of no-go theorems, some of which appeared before but here with essential extensions to non-Markovian dynamics, including the study of the diffusion limit. It allows to exclude certain protocols in the working of chemical motors where only the depth of the energy well is changed in time and not the barrier height between pairs of states. We also show how pre-existing steady state currents are, in general, modified with a multiplicative factor when this time dependence is turned on.

BioWatch: A Noninvasive Wrist-Based Blood Pressure Monitor That Incorporates Training Techniques for Posture and Subject Variability.

Noninvasive continuous blood pressure (BP) monitoring is not yet practically available for daily use. Challenges include making the system easily wearable, reducing noise level and improving accuracy. Variations in each person's physical characteristics, as well as the possibility of different postures, increase the complexity of continuous BP monitoring, especially outside the hospital. This study attempts to provide an easily wearable solution and proposes training to specific posture and individual for further improving accuracy. The wrist watch-based system we developed can measure electrocardiogram and photoplethysmogram. From these two signals, we measure pulse transit time through which we can obtain systolic and diastolic blood pressure through regression techniques. In this study, we investigate various functions to perform the training to obtain blood pressure. We validate measurements on different postures and subjects, and show the value of training the device to each posture and each subject. We observed that the average RMSE between the measured actual systolic BP and calculated systolic BP is between 7.83 to 9.37 mmHg across 11 subjects. The corresponding range of error for diastolic BP is 5.77 to 6.90 mmHg. The system can also automatically detect the arm position of the user using an accelerometer with an average accuracy of 98%, to make sure that the sensor is kept at the proper height. This system, called BioWatch, can potentially be a unified solution for heart rate, SPO2 and continuous BP monitoring.

BioWatch - a wrist watch based signal acquisition system for physiological signals including blood pressure.

A wrist watch based system, which can measure electrocardiogram (ECG) and photoplethysmogram (PPG), is presented in this work. By using both ECG and PPG we also measure pulse transit time (PTT), which studies show to correlate well with blood pressure (BP). The system is also capable of monitoring heart rate using either ECG or PPG and can monitor blood oxygenation by easily replacing the PPG sensors with a different set. In this work, we investigate methods to train a fitting function to convert a PTT measurement to its corresponding systolic BP. We also validate measurements on different postures and show the value of calibrating the device for each posture. This system, called BioWatch, can potentially facilitate continuous and ubiquitous monitoring of ECG, PPG, heart rate, blood oxygenation and BP.

From Langevin to generalized Langevin equations for the nonequilibrium Rouse model.

We investigate the nature of the effective dynamics and statistical forces obtained after integrating out nonequilibrium degrees of freedom. To be explicit, we consider the Rouse model for the conformational dynamics of an ideal polymer chain subject to steady driving. We compute the effective dynamics for one of the many monomers by integrating out the rest of the chain. The result is a generalized Langevin dynamics for which we give the memory and noise kernels and the effective force, and we discuss the inherited nonequilibrium aspects.

Effect of TBCD and its regulatory interactor Arl2 on tubulin and microtubule integrity.

Assembly of the α/ß tubulin heterodimer requires the participation of a series of chaperone proteins (TBCA-E) that function downstream of the cytosolic chaperonin (CCT) as a heterodimer assembly machine. TBCD and TBCE are also capable of acting in a reverse reaction in which they disrupt native heterodimers. Homologs of TBCA-E exist in all eukaryotes, and the amino acid sequences of α- and ß-tubulin isotypes are rigidly conserved among vertebrates. However, the efficiency with which TBCD effects tubulin disruption in vivo depends on its origin: bovine (but not human) TBCD efficiently destroys tubulin and microtubules upon overexpression in cultured cells. Here we show that recombinant bovine TBCD is produced in HeLa cells as a stoichiometric cocomplex with ß-tubulin, consistent with its behavior in vitro and in vivo. In contrast, expression of human TBCD using the same host/vector system results in the generation of TBCD that is not complexed with ß-tubulin. We show that recombinant human TBCD functions indistinguishably from its nonrecombinant bovine counterpart in in vitro CCT-driven folding reactions, in tubulin disruption reactions, and in tubulin GTPase activating protein assays in which TBCD and TBCC stimulate GTP hydrolysis by ß-tubulin at a heterodimer concentration far below that required for polymerization into microtubules. We conclude that bovine and human TBCD have functionally identical roles in de novo tubulin heterodimer assembly, and show that the inability of human TBCD to disrupt microtubule integrity upon overexpression in vivo can be overcome by siRNA-mediated suppression of expression of the TBCD regulator Arl2 (ADP ribosylation factor-like protein).