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Hydrogen lithography has been used to template phosphine-based surface chemistry to fabricate atomic-scale devices, a process we abbreviate as atomic precision advanced manufacturing (APAM). Here, we use mid-infrared variable angle spectroscopic ellipsometry (IR-VASE) to characterize single-nanometer thickness phosphorus dopant layers (δ-layers) in silicon made using APAM compatible processes. A large Drude response is directly attributable to the δ-layer and can be used for nondestructive monitoring of the condition of the APAM layer when integrating additional processing steps. The carrier density and mobility extracted from our room temperature IR-VASE measurements are consistent with cryogenic magneto-transport measurements, showing that APAM δ-layers function at room temperature. Finally, the permittivity extracted from these measurements shows that the doping in the APAM δ-layers is so large that their low-frequency in-plane response is reminiscent of a silicide. However, there is no indication of a plasma resonance, likely due to reduced dimensionality and/or low scattering lifetime.
In this brief report, computed tomography perfusion (CTP) thresholds predicting follow-up infarction in patients presenting <3 hours from stroke onset and achieving ultra-early reperfusion (<45 minutes from CTP) are reported. CTP thresholds that predict follow-up infarction vary based on time to reperfusion: Tmax >20 to 23 seconds and cerebral blood flow <5 to 7 ml/min−1/(100 g)−1 or relative cerebral blood flow <0.14 to 0.20 optimally predicted the final infarct. These thresholds are stricter than published thresholds.
Faster eating rates are associated with increased energy intake, but little is known about the relationship between children’s eating rate, food intake and adiposity. We examined whether children who eat faster consume more energy and whether this is associated with higher weight status and adiposity. We hypothesised that eating rate mediates the relationship between child weight and ad libitum energy intake. Children (n 386) from the Growing Up in Singapore Towards Healthy Outcomes cohort participated in a video-recorded ad libitum lunch at 4·5 years to measure acute energy intake. Videos were coded for three eating-behaviours (bites, chews and swallows) to derive a measure of eating rate (g/min). BMI and anthropometric indices of adiposity were measured. A subset of children underwent MRI scanning (n 153) to measure abdominal subcutaneous and visceral adiposity. Children above/below the median eating rate were categorised as slower and faster eaters, and compared across body composition measures. There was a strong positive relationship between eating rate and energy intake (r 0·61, P<0·001) and a positive linear relationship between eating rate and children’s BMI status. Faster eaters consumed 75 % more energy content than slower eating children (Δ548 kJ (Δ131 kcal); 95 % CI 107·6, 154·4, P<0·001), and had higher whole-body (P<0·05) and subcutaneous abdominal adiposity (Δ118·3 cc; 95 % CI 24·0, 212·7, P=0·014). Mediation analysis showed that eating rate mediates the link between child weight and energy intake during a meal (b 13·59; 95 % CI 7·48, 21·83). Children who ate faster had higher energy intake, and this was associated with increased BMI z-score and adiposity.
We develop a model of legislative policymaking in which individual legislators are concerned with both policy and reelection. Legislators' preferences are private information, and they have two means of communicating their preferences to voters. First, they each have a “party label” that credibly identifies an interval within which their ideal points must lie. Second, their roll call votes may convey additional information about their preferences. Each legislator must therefore tailor his or her votes to his or her district in order to forestall a reelection challenge from the opposing party. In equilibrium, nonsincere voting records will occur mostly in moderate districts, where extreme incumbents are vulnerable to challenges from relatively centrist candidates. In those districts, the most extreme legislators may even choose to vote sincerely and retire rather than compile a moderate voting record. Thus, both roll call scores and candidate types will be responsive to district type. An empirical test of shifts in roll call scores of retiring House members in moderate districts confirms these findings.
We develop a model of adaptive learning with social comparisons. Actors are more likely to choose actions that recently yielded satisfactory payoffs; satisfaction is evaluated relative to an aspiration level that reflects previous payoffs and possibly other players’ payoffs. This captures the phenomenon of social comparison via reference groups. We show that if agents compare themselves to those who are receiving higher payoffs then in stable outcomes all payoffs must be equal. If, however, agents’ aspirations are driven by less ambitious social comparisons then very unequal distributions can be stable. We apply our general results to collective action problems in socio-political hierarchies and derive conditions for stable exploitation. Finally, we develop a computational model, which shows that increases in payoff inequality make outcomes less stable.
How much can a constituency influence the power of its representative in the legislature? This article develops a theoretical model of the constituency basis of legislator influence. The key players in the model are interest groups that may receive targeted transfers from the legislature. The model predicts that the amount of transfers that such groups receive is increasing in their ability to help a party win a legislative seat in the next election. This claim is tested using the changes in Japanese central-to-municipality transfers after a representative passes away while in office. The study finds that electorally ‘strong’ constituency groups do not lose transfers when they lose their representatives. However when ‘weak’ constituency groups lose their representatives, the transfers decrease.
This article develops a theory of bureaucratic influence on distributive politics. Although there exists a rich literature on the effects of institutions such as presidents, electoral systems, and bicameralism on government spending, the role of professional bureaucrats has yet to receive formal scrutiny. In the model, legislators bargain over the allocation of distributive benefits across districts. The legislature may either “politicize” a program by bargaining directly over pork and bypassing bureaucratic scrutiny, or “professionalize” it by letting a bureaucrat approve or reject project funding in each district according to an underlying quality standard. The model predicts that the legislature will professionalize when the expected program quality is high. However, politicization becomes more likely as the number of high-quality projects increases and under divided government. Further, more competent bureaucrats can encourage politicization if the expected program quality is low. Finally, politicized programs are larger than professionalized programs.
We develop a model of electoral competition in which two parties compete for votes amongst three groups of voters. Each party first internally selects one of two candidates to run in a general election. Candidates within a party share a fixed ideological platform and can promise a distribution of a unit of public spending across groups. Without primary elections, the selection process is random. With primary elections, an ideologically friendly subset of the voters strategically chooses the candidate. In the basic model, primary elections cause politicians to cater to extreme groups rather than a moderate group with many “swing voters.” The amount promised to extreme groups is decreasing in the ideological polarization of those groups, while each party's probability of victory is increasing in the size and extremity of its favored group. We also find that an incumbency advantage reduces the amount promised to extremists, and therefore benefits moderates.
We present a model of learning and policy choice across governments. Governments choose policies with known ideological positions but initially unknown valence benefits, possibly learning about those benefits between the model's two periods. There are two variants of the model; in one, governments only learn from their own experiences, whereas in the other they learn from one another's experiments. Based on similarities between these two versions, we illustrate that much accepted scholarly evidence of policy diffusion could simply have arisen through independent actions by governments that only learn from their own experiences. However, differences between the game-theoretic and decision-theoretic models point the way to future empirical tests that discern learning-based policy diffusion from independent policy adoptions.
By skipping managers and appealing directly to politicians, whistleblowers can play a critical role in revealing organizational information. However, the protection of whistleblowers can affect managers' abilities to provide employees with incentives to exert effort. This paper explores this tradeoff with a model of agency decision-making under incomplete information. In the game, an employee's effort determines a project's quality, and a manager chooses whether to approve the project and discipline the employee. The employee and politician wish for only “good” projects to be approved. By whistleblowing, an employee reveals the quality to a politician outside of the organization, who may override the manager's decision. A key finding is that from the politician's perspective, the benefits of whistleblower protections depend on the preferences of the manager. If the manager is inclined toward approving projects, then the costs of lower employee effort may outweigh the informational benefits of whistleblowing. The optimal policy may then be to ban whistleblowing. By contrast, when the manager is inclined toward rejecting projects, whistleblower protections prevent him or her from suppressing effort and are unambiguously beneficial.
Malapportionment of seats in bicameral legislatures, it is widely argued, confers disproportionate benefits to overrepresented jurisdictions. Ample empirical research has documented that unequal representation produces unequal distribution of government expenditures in bicameral legislatures. The theoretical foundations for this empirical pattern are weak. It is commonly asserted that this stems from unequal voting power per se. Using a noncooperative bargaining game based on the closed-rule, infinite-horizon model of Baron and Ferejohn (1989), we assess the conditions under which unequal representation in a bicameral legislature may lead to unequal division of public expenditures. Two sets of results are derived. First, when bills originate in the House and the Senate considers the bill under a closed rule, the equilibrium expected payoffs of all House members are, surprisingly, equal. Second, we show that small-state biases can emerge when (1) there are supermajority rules in the malapportioned chamber, (2) the Senate initiates bills, which produces maldistributed proposal probabilities, and (3) the distributive goods are “lumpy.”We thank seminar participants at New York University, the University of Pennsylvania, and the 2002 annual meeting of the American Political Science Association for helpful comments. James Snyder and Michael Ting gratefully acknowledge the financial support of National Science Foundation Grant SES-0079035. Stephen Ansolabehere gratefully acknowledges the support of the Carnegie Corporation under the Carnegie Scholars program. This paper was written while Michael Ting was at the University of North Carolina at Chapel Hill, and he thanks the Department of Political Science there for their support.
Solar-blind imaging arrays based on AlGaN p-i-n structures are of high interest for defense applications. We have studied the material issues involved in development of such imaging arrays and have developed discrete photodetector devices with a high external quantum efficiency (EQE) and imaging arrays of high operability.
For the discrete devices, a record EQE of 58.1% peaking at 274 nm under zero volt bias was obtained without using an anti-reflecting (AR) coating. The EQE was seen to have a slight voltage dependence: going up to 64.5% at –5V reverse bias. The responsivity had a drop-off by one order of magnitude for a wavelength change of 4 nm on both the shorter and longer wavelength side. The material quality and uniformity was found to be very good leading to the development of 256 × 256 arrays. A high yield along with uniform, high EQE was obtained for the detector devices in the array leading to a high operability of 99.8%.
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