Stability of Electron and X-ray Emission in a LiTaO3 crystal-based pyroelectric accelerator driven by a periodically varying temperature

Conventional X-ray sources are bulky and require a high DC voltage. Pyroelectric X-ray generator technology has enabled us to develop portable, low-voltage X-ray sources for use in materials analysis, imaging, and other applications. The development of intense and reliable sources of charged particle beams is a current within accelerator physics in its own right. Changing the temperature of a single crystal of Lithium Tantalate (LiTaO3) in moderate vacuum conditions leads to generation of a strong electric field. If a metal target is placed nearby facing the crystal, the uncompensated polarization generated during the heating or cooling of the crystal causes the ejection of electrons from either the dielectric layer on the surface of the crystal or from the metal target depending on the polarity. These electrons are than accelerated by the strong electric field gaining an energy of up to 100 keV. The energy of these electrons can be determined by measuring the end-point energy of the X-ray spectrum that results from the interaction of the electrons with the target. It has been experimentally confirmed that a pyroelectric crystal installed in a chamber with a residual gas pressure of about 2 mTorr could be used to generate electrons with energy of up to 35 keV. Here, we present studies of the features of the electron flux in a pyroelectric accelerator and how they are affected by the pressure of the residual gas, and the distance between the crystal and the target. The connection between monoenergetic electron production in a pyroelectric generator and avalanche discharge in a gas is discussed. It is demonstrated that using a pair of crystals enables us to double the acceleration potential. Using the same setup an unknown sample was fluoresced using a pyroelectric accelerator in order to analyse its elemental content. In this report we demonstrate how pyroelectric accelerators can complement conventional X-ray tubes and radioisotopes or even large central facilities. Pyroelectric X-ray generator technology is currently being developed to provide a reliable, compact, stable, and reproducible X-ray source with controllable parameters, which does not require a high-voltage DC voltage or the use of hazardous (radioactive) materials.<br/

The Capacity of a Finite Field Matrix Channel

The Additive-Multiplicative Matrix Channel (AMMC) was introduced by Silva, Kschischang and Kötter in 2010 to model data transmission using random linear network coding. The input and output of the channel are $n\times m$ matrices over a finite field $\mathbb{F}_q$. When the matrix $X$ is input, the channel outputs $Y=A(X+W)$ where $A$ is a uniformly chosen $n\times n$ invertible matrix over $\mathbb{F}_q$ and where $W$ is a uniformly chosen $n\times m$ matrix over $\mathbb{F}_q$ of rank $t$.Silva et al. considered the case when $2n\leq m$. They determined the asymptotic capacity of the AMMC when $t$, $n$ and $m$ are fixed and $q\rightarrow\infty$. They also determined the leading term of the capacity when $q$ is fixed, and $t$, $n$ and $m$ grow linearly. We generalise these results, showing that the condition $2n\geq m$ can be removed. (Our formula for the capacity falls into two cases, one of which generalises the $2n\geq m$ case.) We also improve the error term in the case when $q$ is fixed

Sacred Texts and Profane Realities:Islamic Criminal Laws (Ḥudūd) and Children’s Rights in Pakistan

This article examines the impact of Islamic criminal laws (ḥudūd), particularly the Zina Ordinance, on children’s rights in Pakistan. By analyzing the judgments of the Federal Shariat Court (FSC) and the Shariat Appellate Bench (SAB) of the Supreme Court, the study identified three key trends in case law. First, ambiguity in defining adulthood—whether based on statutory age limits or biological puberty—has resulted in inconsistent judicial decisions. Second, the judicial approach on minors’ consent in sexual offenses evolved over time, shifting from accepting consent to rejecting it, aligning with the principle of statutory rape. Third, while leniency in sentencing underage offenders reflects an emphasis on rehabilitation, it raises questions about deterrence and consistency. The findings of this research underscore the critical role of procedural laws and legal certainty in safeguarding children’s rights within a mixed legal framework of Islamic laws and common law tradition

Climate change as fake news.:Positive attribute framing as a tactic against corporate reputation damage from the evaluations of sceptical, right-wing audiences

PurposeThe paper aims to examine whether CSR communication about a company’s support for climate change created using different content framing categories (positive vs negative) can lead climate change-sceptical audiences to positively influence their evaluations of the credibility of CSR communication, of a company and its actions, and lead to higher purchase intentions.Design/methodology/approachThe paper used an experimental design. About 266 respondents recruited via the Prolific platform were invited to participate in an online study. A between-subject design was used, and data was analysed using the bootstrapping technique, allowing to identify moderators of the relationship between CSR communication framing and different evaluations of a company.FindingsThe paper provides empirical support for the role of political preferences and climate change beliefs in predicting the preference for positive attribute framing among climate change sceptical audiences. It is argued that climate change sceptics are still in the process of deliberation about whether climate change is occurring.Research limitations/implicationsThe research findings may not be generalizable to countries where support for climate change is low, and a technique like attribute framing may not lead to noticeable differences in message reception.Practical implicationsThe paper underscores the impact of the type of attribute framing in CSR communication on different aspects of company evaluations depending on beliefs in climate change. Commercial communicators should additionally invest in climate change education to address the climate change challenge.Social implicationsAddressing climate change effectively requires support from companies to communicate their CSR efforts purposefully and to address climate change sceptical audiences.Originality/valueThe paper identifies beliefs in climate change as an important moderator of CSR communication attribute framing effectiveness

Electoral Gender Quotas and Democratic Legitimacy

Gender quotas are used to elect most of the world’s legislatures. Still, critics contend that quotas are undemocratic, eroding institutional legitimacy. We examine whether quotas diminish citizens’ faith in political decisions and decision making processes. Using survey experiments in twelve democracies with over 17,000 respondents, we compare the legitimacy-conferring effects of both quota-elected and non-quota-elected local legislative councils relative to all-male councils. Citizens strongly prefer gender balance, even when it is achieved through quotas. Though we observe a quota penalty, wherein citizens prefer gender balance attained without a quota relative to quota-elected institutions, this penalty is often small and insignificant, especially in countries with higher-threshold quotas. Quota debates are thus better framed around the most relevant counterfactual: the comparison is not between women’s descriptive representation with and without quotas, but between men’s political dominance and women’s inclusion

Mobile Calibration for Bus-Based Urban Sensing

In bus-based sensing, public transport serves as a mobile urban sensing platform. While offering much higher geographical coverage, the low-cost sensors mounted on vehicles can be less accurate and demand more frequent calibration, which may be challenging for large vehicles fleets. As calibration is performed by relating mobile sensor readings to those of fixed reference stations, the placement of reference stations is very important. In this work, we propose an algorithm for computing the optimal reference stations locations to maximize the sensing coverage. Contrary to prior work, the coverage is defined in terms of geographical area , extending a certain distance away from the route trajectory representing the actual sensing capacity of the vehicles. The proposed algorithm computes it using geographical set operations, such as spatial join and subtraction to compute the unique contribution of each bus route. We evaluate the approach using real bus trajectories from Manhattan, US and compare it with a random baseline and prior work. The results indicate that the given the bus routes, a complete sensing coverage can be achieved using a single reference station with a maximum of 2-hop calibration path