Quantum metrology and its application in biology

Quantum metrology provides a route to overcome practical limits in sensing devices. It holds particular relevance to biology, where sensitivity and resolution constraints restrict applications both in fundamental biophysics and in medicine. Here, we review quantum metrology from this biological context, focusing on optical techniques due to their particular relevance for biological imaging, sensing, and stimulation. Our understanding of quantum mechanics has already enabled important applications in biology, including positron emission tomography (PET) with entangled photons, magnetic resonance imaging (MRI) using nuclear magnetic resonance, and bio-magnetic imaging with superconducting quantum interference devices (SQUIDs). In quantum metrology an even greater range of applications arise from the ability to not just understand, but to engineer, coherence and correlations at the quantum level. In the past few years, quite dramatic progress has been seen in applying these ideas into biological systems. Capabilities that have been demonstrated include enhanced sensitivity and resolution, immunity to imaging artifacts and technical noise, and characterization of the biological response to light at the single-photon level. New quantum measurement techniques offer even greater promise, raising the prospect for improved multi-photon microscopy and magnetic imaging, among many other possible applications. Realization of this potential will require cross-disciplinary input from researchers in both biology and quantum physics. In this review we seek to communicate the developments of quantum metrology in a way that is accessible to biologists and biophysicists, while providing sufficient detail to allow the interested reader to obtain a solid understanding of the field. We further seek to introduce quantum physicists to some of the central challenges of optical measurements in biological science.Comment: Submitted review article, comments and suggestions welcom

Slicing the Pie: A Call for Congress to Enact Single-Factor Payroll Apportionment of Interstate Business Revenue

Almost all states levy some form of corporate income tax. In administering a corporate income tax system, states must make a series of policy decisions, including the tax rate and tax base. A more interesting problem arises, however, when considering corporations that do business in multiple states: how to determine the portion of income attributable to business within each state. This policy of apportionment is a crucial element of a corporate income tax system. Although the federal government has considered involving itself in determining how this income is apportioned to the various states, it never has. States have very little federal restrictions on their capacity to determine for themselves how much interstate corporate income should be subject to their corporate income taxes. This leaves the states the crucial task of “slicing a taxable pie[.]” While there have been efforts to bring uniformity to the states’ apportionment schemes, states have recently splintered in their approaches. This is driven in large part by the states’ incentive to maximize their revenues while shifting tax burdens onto out-of-state corporations. The result is a system that is increasingly complex and difficult for corporations to navigate. It is a system that often subjects interstate corporations to overlapping taxation. Moreover, it is a system that increasingly pushes its tax burdens onto corporations that have very little ability to achieve political recourse. It is time for Congress to step in once and for all to fix this broken system and institute a simple, uniform formula of apportionment that guarantees states cannot reach out and tax those who are largely unrepresented in the state assemblies. Congress should implement single-factor payroll apportionment through legislation that mandates apportionment according to the percentage of the business’s payroll expenses paid to residents of that state. This formula presents the most straightforward approach to apportioning income with the lowest costs of compliance and administration. Applying it at the congressional level assures uniformity and negates the states’ incentive to craft their own laws to maximize the reach of their tax schemes. Further, it focuses the state’s taxing power on the corporations that employ individuals within its border — the very businesses that are most likely to be represented in the political process that determines the tax rate

Defensive aggregation to predatory threat in the laboratory rat: behavioural, neural, pharmacological and epigenetic correlates

Abstract: Defensive aggregation is the tight clumping together of conspecifics observed in response to predatory threat across many species. While much field research has explored this social response to threat, in particular the important survival advantages it affords, it has received little examination in the laboratory. Chapter 2 of this thesis presents the first laboratory rodent model of defensive aggregation, demonstrating that it can be readily elicited in groups of four rats presented with an unconditioned stressor (cat fur or bright light). This provides a novel opportunity to explore the more subtle benefits accrued from defensive aggregation as well as its underlying neurobiology and pharmacology. Chapter 3 illustrates that defensive aggregation has a hitherto unknown social buffering effect that reduces neural and behavioural stress responsivity and facilitates reengagement in important non-threat-related behaviours. It also demonstrates that stable active and passive stress coping rats exist amongst populations that are group exposed to predator threat. Chapter 4 demonstrates that the neuropeptide oxytocin acts at vasopressin V1ARs to selectively promote social responding to threat without increasing anxiety-like behaviour. This suggests that developing novel pharmacotherapies that target V1ARs may prove useful for the treatment of chronic social withdrawal in the face of stress, which occurs in numerous psychiatric disorders. Finally, Chapter 5 provides the first report of striking epigenetic differences in the medial amygdala AVP system between active and passive coping rats, providing a potential mechanism through which the proactive response style seen in some animals confronted with threat might be maintained. It is hoped that the work presented in this thesis has served as a foundation for the future investigation of the neurobiological mechanisms driving, and adaptive benefits underlying, the social response to threat and an active stress coping strategy

UI-Design driven model-based testing

Testing interactive systems is notoriously difficult. Not only do we need to ensure that the functionality of the developed system is correct with respect to the requirements and specifications, we also need to ensure that the user interface to the system is correct (enables a user to access the functionality correctly) and is usable. These different requirements of interactive system testing are not easily combined within a single testing strategy. We investigate the use of models of interactive systems, which have been derived from design artefacts, as the basis for generating tests for an implemented system. We give a model-based method for testing interactive systems which has low overhead in terms of the models required and which enables testing of UI and system functionality from the perspective of user interaction

Insulin Nucleation Using Voltage Clamping and Current Clamping Techniques

Crystallization of proteins is the prerequisite to obtaining three-dimensional molecular structures; by X-ray crystallography. The knowledge of protein structures is foundational and could pave ways to the understanding of a protein’s functions. However, obtaining single crystals is challenging and often a bottleneck let alone the need of satisfactory diffraction quality. In this thesis, quartz nanopipettes are used to spatially confine the location of nucleation and crystal growth at a nanometer scale. Current and voltage clamping techniques are employed to induce phase transition and subsequent crystal formation via external controls. Throughout the process, we can monitor and control the electrical current/potential that controls mass transport for local concentration adjustment

The Strange Tale of Wesley and Florence Garrison: Racial Crosscurrents of the Postwar Florida Republican Party

For the first two thirds of the 20th Century, the Republican Party of Florida had a well-deserved reputation for being quiet, weak, and ineffectual. The Democratic Party dominated electoral politics so completely that some counties in the panhandle and north central Florida prided themselves on having no registered Republicans. Yet at the 1952 state Republican convention, held in the sleepy college town of Gainesville, the participants acted as if their meeting mattered. A group of upstarts led by Miami real estate developers Wesley and Florence Garrison, a couple some regarded as reformers and some regarded as rabblerousers, commandeered the front row of seating and refused to allow the state executive committee to take their positions on stage. After the Alachua County sheriff restored order, the Garrisons and their supporters made their presence known by repeatedly interrupting the opening roll call with chants of contest and communist, and slamming their chair legs loudly against the tile floor. At issue was the party\u27s decision to abandon the primary election and select its delegates to the Republican national convention without participation from rank and file party members, a choice the Garrisons vehemently opposed. Despite the repeated distractions, however, the state party went on with its agenda and appointed a delegate slate that excluded the Gamsons and their allies

Issue Publics Gone Wild Or The End Of Narrow Interests

Issue public theory holds that individuals are more likely to base political judgments, such as the decision of who to vote for on election day, on issues that are particularly important to them. This subset of issues is presumed to be relatively small in quantity for most individuals, allowing them to specialize in information gathering and attention. There is reason to believe the nature of issue publics has significantly changed in recent years as a result of profound shifts in the information environment. Many of the traditional findings within the literature are reassessed using data primarily from the 2008 Presidential election. Though significant changes are found, they do not, as theorized, represent a strengthening of issue publics within society. If anything, people appear to emphasize a larger array of issues today than ever before and rely no more heavily upon important issues than unimportant ones in their voting decision. Evidence is found, though, for a mediating role of the particular form of media the individual engages in