Single molecule DNA sequencing via transverse electronic transport using a graphene nanopore: A tight-binding approach

We report a tight-binding model study of two-terminal graphene nanopore based device, for sequential determination of DNA bases. Using Greens function approach we calculate conductance spectra, I-V response and also the changes in local density of states (LDOS) profile as four different nucleobases inserted one by one into the pore embedded in the zigzag graphene nanoribbon (ZGNR). We find distinct features in LDOS profile for different nucleotides and the same is also present in conductance and I-V response. We propose the actual working principle of the device, by setting the bias across the pore to a fixed voltage (this voltage gives maximum discrimination between characteristic current of the four nucleotides) and translocating the ss-DNA through the nanopore using a transverse electric field while recording the characteristic current of the nucleotides. Not only the typical current output is much larger than previous results, but the seaparation between them for different bases are also definite. Our investigation provides high accuracy and significant amount of distinction between different nucleotides.Comment: 6 pages, 5 figure

Mobility and Conflict

We study the role of inter-group differences in the emergence of conflict. In our setting, two groups compete for the right to allocate societys resources, and we allow for costly intergroup mobility. The winning group offers an allocation, that the opposition can either accept, or reject and wage conflict. Expropriating a large share of resources increases political strength by attracting opposition members, but such economic exclusion implies lower per capita shares and higher risk of conflict. In equilibrium, allocations are non-monotonic in the cost of mobility. Moreover, limited commitment with respect to mobility gives rise to inefficient conflict in equilibrium.conflict, inter-group mobility, political competition, resource allocation

Mobility and Conflict

We study the role of inter-group differences in the emergence of conflict. In our setting, society comprises two groups who compete in every period for political power, i.e. the right to allocate economic resources between the groups. Individuals can move from one group to another at a cost: this cost of mobility is the index of inter-group differences. Since mobility is costly, the group in power can keep a larger share for itself. The extent of such economic exclusion is limited by two constraints: excessive exclusion reduces the opposition’s opportunity cost of engaging in political conflict (conflict constraint) and, if a group keeps too much for itself, individuals switching from the other group will dilute the per capita share of resources (mobility constraint). In determining the optimal group size by attracting switchers, the incumbent faces a trade-off between low per capita surplus and high political strength. We characterize the resource allocations, group membership decisions and conflict decisions that arise in equilibrium. The two mechanisms of conflict and mobility act as constraints to expropriation, and the optimal sharing is dictated by which constraint binds. The extent of sharing turns out to be non-monotonic in the cost of mobility. We show that the limited commitment with respect to switching can lead to inefficient conflict in equilibrium. We also derive several testable predictions about when conflict will arise. Specifically, we show that conflict may arise when the cost of mobility is moderate, but may not necessarily emerge when the cost is high

Mobility and Conflict

We study the role of intergroup mobility in the emergence of conflict. Two groups compete for the right to allocate society's resources. We allow for costly intergroup mobility. The winning group offers an allocation, which the opposition can accept or reject, and wage conflict. Agents can also switch group membership. Expropriating a large share of resources increases political strength by attracting opposition members, but implies a higher threat of conflict. Our main finding is that the possibility of intergroup mobility affects the likelihood of conflict in a nonmonotonic way. Open conflict can arise at intermediate costs of mobility. (JEL D71, D72, D74

Mobility and Conflict

Accepted manuscript version. Published version at <a href=http://doi.org/10.1257/mic.20130055>http://doi.org/10.1257/mic.20130055</a>.We study the role of intergroup mobility in the emergence of conflict. Two groups compete for the right to allocate society's resources. We allow for costly intergroup mobility. The winning group offers an allocation, which the opposition can accept or reject, and wage conflict. Agents can also switch group membership. Expropriating a large share of resources increases political strength by attracting opposition members, but implies a higher threat of conflict. Our main finding is that the possibility of intergroup mobility affects the likelihood of conflict in a nonmonotonic way. Open conflict can arise at intermediate costs of mobility. (JEL D71, D72, D74

Elastic Wave Propagation in Sinusoidally Corrugated Waveguides

The ultrasonicwave propagation in sinusoidally corrugated waveguides is studied in this paper. Periodically corrugated waveguides are gaining popularity in the field of vibration control and for designing structures with desired acoustic band gaps. Currently only numerical method (Boundary Element Method or Finite Element Method) based packages (e.g., PZFlex) are in principle capable of modeling ultrasonic fields in complex structures with rapid change of curvatures at the interfaces and boundaries but no analyses have been reported. However, the packages are very CPU intensive; it requires a huge amount of computation memory and time for its execution. In this paper a new semi-analytical technique called Distributed Point Source Method (DPSM) is used to model the ultrasonic field in sinusoidally corrugated waveguides immersed in water where the interface curvature changes rapidly. DPSM results are compared with analytical solutions. It is found that when a narrow ultrasonic beam hits the corrugation peaks at an angle, the wave propagates in the backward direction in waveguides with high corrugation depth. However, in waveguides with small corrugation the wave propagates in the forward direction. The forward and backward propagation phenomenon is found to be independent of the signal frequency and depends on the degree of corrugation

Determining the purity of single-helical proteins from electronic specific heat measurements

We present a theoretical investigation of the electronic specific heat (ESH) at constant volume (Cv) of single-helical proteins modeled within the tight-binding (TB) framework. We study the effects of helical symmetry, long-range hopping, environment and biological defects on thermal properties. We employ a general TB model to incorporate all parameters relevant to the helical structure of the protein. In order to provide additional insights into our results for the ESH, we also study the electronic density of states for various disorder strengths. We observe that the variation of the specific heat with disorder is very different in low and high temperature regimes, though the variation of ESH with temperature possesses a universal pattern upon varying disorder strengths related to environmental effects. Lastly, we propose an interesting application of the ESH spectra of proteins. We show that by studying the ESH of single-helical proteins, one can distinguish a defective sample from a pure one. This observation can serve as the basis of a screening technique that can be applied prior to a whole genome testing, thereby saving valuable time & resources