Modal abundances of CAIs: Implications for bulk chondrite element abundances and fractionations

Modal abundances of Ca,Al-rich inclusions (CAIs) are poorly known and reported data scatter across large ranges. We combine reported CAI modal abundances and our own set, and present a complete list of CAI modal abundances in carbonaceous chondrites. This includes (in area%): CV: 2.98, CM: 1.21, Acfer 094: 1.12, CO: 0.99, CK/CV (Ningqiang & DaG 055): 0.77, CK: 0.2, CR: 0.12 and CB: 0.1. CAIs are Poisson distributed and if only small areas (<1000 mm2) are studied, the data are probably not representative of the true CAI modal abundances, explaining their reported large scatter in a single chondrite group. Carbonaceous chondrites have excess bulk Al concentrations when compared to the CI-chondritic value. We find a correlation between this excess and CAI modal abundances and conclude that the excess Al was delivered by CAIs. The excess Al is only a minor fraction (usually ~10 rel%, but 25 rel% in case of CVs) of the bulk chondrite Al and cannot have contributed much 26Al to heat the chondrite parent body. Ordinary, enstatite, R- and K-chondrites have an Al deficit relative to CI chondrites and only very low CAI modal abundances, if any are present at all. Carbonaceous chondrites also had an initial Al deficit if the contribution of Al delivered by CAIs is subtracted. Therefore all chondrites probably lost a refractory rich high-T component. Only minor amounts of CAIs are present in the matrix or have been present in the chondrule precursor aggregates. Most CAI size distributions contain more than one size population, indicating that CAIs from within a single meteorite group had different origins.Comment: Meteoritics & Planetary Sciences (in press

Magnetic field of superconductive in-vacuo undulators in comparison with permanent magnet undulators

During the last few years superconductive undulators with a period length of 3.8 mm and 14 mm have been built. In this paper scaling laws for these novel insertion devices are presented: a simple analytic formula is derived which describes the achievable magnetic field of a superconcuctive undulator as a function of gap-width and period length.Comment: Accepted for publication in Nuclear Instruments and Methods in Physics Research, Section

A proposed framework that enhances the quality of cyber security audits

The need to protect information systems or assets remains crucial today. Innovations in technology have led to rapid developments and as technology continues to advance, so is the need to protect information systems. Amongst numerous effects of cyber-attacks on organizations, huge financial losses which in turn affect the economy have since been reported. Cyber security audits need to be strengthened to tighten the protection of information systems. The importance of cybersecurity audits is widely endorsed in literature. Nonetheless, frameworks used to audit cybersecurity are viewed as‘sometimes' weak links to cybersecurity due to their drawbacks in auditing cyber security. A review of literature indicated that cyber-attacks are more rampant in the African continent with the financial sector being the most targeted. Literature also highlighted that the use of relevant frameworks for auditing cyber security improves the quality and effectiveness of audits thereby enhancing cyber security. Studies in information systems have mostly looked at the adoption of frameworks, types of cyber threats and tools needed to audit. Nonetheless, it is important to note that few scholars have examined the applicability and effectiveness of the existing frameworks in auditing cyber security. Furthermore, previous studies emphasize on enhancing cyber security without a particular focus on auditing cyber security including assessing the role of the auditor during the process. As a result, this study looked at cyber security from an auditing perspective with a particular focus on the strengths and weaknesses of the current frameworks that are being used to audit cyber security including. The study also looked at the factors that enhance the effectiveness of cyber security audits. The study draws from different theories, literature and from the strengths and drawbacks of existing frameworks to create an explanatory model. To statistically test and evaluate the model, a quantitative research approach was employed to collect, analyze, and interpret data from South Africa. Data was collected using a questionnaire which was distributed to IT auditors and cyber security professionals from the Information Systems Audit and Control Association (ISACA) South African chapter members. The National Institute of Standards and Technology (NIST) cyber security framework was found to be the widely adopted framework followed by the International Organization for Standardization (ISO) standards, with the Control Objectives for Information Technologies (COBIT) being the least employed framework. The COBIT framework was found to be more aligned to Information Technology governance rather than cyber security. Furthermore, results of this study indicate that effectiveness of cyber security audits is dependent upon competencies of auditors including their ethics and integrity. Results further indicate that frameworks used for auditing are effective to some extent if properly implemented. A proper alignment of an auditor's competencies which include ethics and integrity, and an adoption of a relevant framework will result in effective cyber security audits that reduce the risks of cyber-attacks. Concerning the contribution to practice, results from this study can help organizations to determine and review focus areas of cyber security auditing that they need to emphasize and develop on. Furthermore, the developed model can be used by auditors to develop an audit plan and conduct audits that are effective in identifying, protecting, detecting, preventing, and recovering information systems or assets. The methodological, theoretical, and practical contributions are further discussed in this thesis along with limitations, recommendations, and areas for future research

Improving Aeromagnetic Calibration Using Artificial Neural Networks

The Global Positioning System (GPS) has proven itself to be the single most accurate positioning system available, and no navigation suite is found without a GPS receiver. Even basic GPS receivers found in most smartphones can easily provide high quality positioning information at any time. Even with its superb performance, GPS is prone to jamming and spoofing, and many platforms requiring accurate positioning information are in dire need of other navigation solutions to compensate in the event of an outage, be the cause hostile or natural. Indeed, there has been a large push to achieve an alternative navigation capability which performs nearly as well as GPS. One navigation method which has shown promise to increase navigation performance of aircraft utilizes magnetic anomalies[1] - local variations in the Earth\u27s crust - to discern position. One significant drawback to this approach is the magnetic disturbance generated by the aircraft itself, which must be accounted for and eliminated. Current calibration procedures involve placing the magnetometer on a long stinger far from the aircraft body to minimize interference with the magnetic anomaly signal. While some aircraft permit the addition of stingers, many do not. No calibration procedure exists which satisfies potential location restraints of the magnetometer and the calibration problem for these less ideal aircraft, especially potentially magnetically noisy platforms such as an F-16. Current linear models which attempt to correct mild disturbance fields on more ideal aircraft exist. We propose that a more sophisticated model is necessary to make magnetic navigation platform agnostic. Specifically, we show that a deep learning approach and the utilization of more inputs than the current de facto calibration procedure - known in the literature as Tolles-Lawson - can achieve a 90% reduction in platform based magnetic disturbance signals

One-dimensional Rydberg Gas in a Magnetoelectric Trap

We study the quantum properties of Rydberg atoms in a magnetic Ioffe-Pritchard trap which is superimposed by a homogeneous electric field. Trapped Rydberg atoms can be created in long-lived electronic states exhibiting a permanent electric dipole moment of several hundred Debye. The resulting dipole-dipole interaction in conjunction with the radial confinement is demonstrated to give rise to an effectively one-dimensional ultracold Rydberg gas with a macroscopic interparticle distance. We derive analytical expressions for the electric dipole moment and the critical linear density of Rydberg atoms.Comment: 4 pages, 2 figure

Stories with Strangers: A Community Building Library at Regis University

The authors share foundational texts and topics of engagement that led to an event called: “Stories with Strangers: A Community Building Library at Regis University.” The event was named, “Stories with Strangers” to highlight the “stories” of lived experience as well as the importance of sharing those stories with “strangers” to grow understanding, build relationships, and establish shared values with each other, with the hope of creating a common good. The texts and topics of engagement that led to the event are shared, including: the concept of the “common good” and in particular, David Hollenbach’s The Common Good and Christian Ethics; the field of Library and Information Studies (LIS) and in particular, racism in the field; the AJCU Eyes to See: An Anti-Racism Examen; Danielle Allen’s Talking to Strangers; and The Human Library model. The authors also share details of planning for the event, details of the event itself, feedback from participants, and the authors’ reflections on the event. In sharing details of the formation and impact of this event, the authors hope to provide an instance of imagining the impossible, taking root in hope, and growing that vision into a reality