Analysis of Bacteriorhodopsin Suspended in a Bilayer Lipid Membrane

The bacteriorhodopsin protein’s unique characteristic of proton pumping can convert light energy to electric energy. The aim of this research was to generate photocurrent using bacteriorhodopsin in a bi-layer lipid membrane. Lipid monolayer and bilayer were formed using painting and folding methods, respectively. Capacitance and resistance of the lipid membranes were measured and used to validate the best methodology. My results show that the folding method is more efficient in incorporating Bacteriorhodopsin. The photocurrent was generated by illuminating a green laser (532 nm) on the bilayer lipid membranes. The patch clamp electrophysiology technique was used to apply voltage across the lipid membrane and to record photocurrent. For the membrane capacitance and resistance, the ranges were (1.70E-01- 7.50E-01 uF/cm2) and (0.30 - 0.49 GΩ), respectively. The photocurrent density produced was between 5.3 pA/cm2 and 7.1 pA/cm2

A Tight Uniform Continuity Bound for Equivocation

We prove a tight uniform continuity bound for the conditional Shannon entropy of discrete finitely supported random variables in terms of total variation distance.Comment: 4 pages, streamlined the proof in v2, minor changes + added a clarifying sentence in v

Towards a resolution of the spin alignment problem

Consider minimizing the entropy of a mixture of states by choosing each state subject to constraints. If the spectrum of each state is fixed, we expect that in order to reduce the entropy of the mixture, we should make the states less distinguishable in some sense. Here, we study a class of optimization problems that are inspired by this situation and shed light on the relevant notions of distinguishability. The motivation for our study is the spin alignment conjecture introduced recently in Ref.~\cite{Leditzky2022a}. In the original version of the underlying problem, each state in the mixture is constrained to be a freely chosen state on a subset of $n$ qubits tensored with a fixed state $Q$ on each of the qubits in the complement. According to the conjecture, the entropy of the mixture is minimized by choosing the freely chosen state in each term to be a tensor product of projectors onto a fixed maximal eigenvector of $Q$, which maximally ``aligns'' the terms in the mixture. We generalize this problem in several ways. First, instead of minimizing entropy, we consider maximizing arbitrary unitarily invariant convex functions such as Fan norms and Schatten norms. To formalize and generalize the conjectured required alignment, we define \textit{alignment} as a preorder on tuples of self-adjoint operators that is induced by majorization. We prove the generalized conjecture for Schatten norms of integer order, for the case where the freely chosen states are constrained to be classical, and for the case where only two states contribute to the mixture and $Q$ is proportional to a projector. The last case fits into a more general situation where we give explicit conditions for maximal alignment. The spin alignment problem has a natural ``dual" formulation, versions of which have further generalizations that we introduce.Comment: 36 pages. Comments are welcome

Understanding inequality in employment: an analysis of the subjective context

This paper provides an analysis of the role of context in inequality in employment by using the setting of Saudi public organisations. We focus on tribe and religion as they represent the major cultural force in Saudi public organisations and they hold major power and resources. We conducted interviews and focus-group discussion with employees from dominant and non-dominant groups. We utilised the multilayers framework to help us go beyond the basic analysis of the descriptive and analytical context to focus on the deep analysis of the subjective context in understanding inequality in employment. Our findings revealed the perpetuation of inequality in employment is considered a political strategy which is reinforced by the state and supported by tribal structure and religious establishment. In the absence of equality legislation, equality in employment seen as a form of modern liberal and social democracy which is why not supported by dominant groups. The subjective analysis of the context provides potential implication to enhance theory and practice on the contextualisation and operationalisation of inequality in employment

Timing and Composition of Volcanism at Harrat Ithnayn, Western Saudi Arabia

Western Saudi Arabia hosts a number of young volcanic fields, known as “Harrats”. Harrats cover a significant proportion of western Saudi Arabia and are associated with significant volcanic hazards. However, the ultimate cause of volcanic activity remains unclear. Younger volcanism (<12 Ma) is clearly represented by the north-south-trending region known as the Makkah-Madinah-Nafud (MMN) line, which consists of three moderate sized volcanic fields: Harrat Rahat, Harrat Khaybar, and Harrat Ithnayn. Harrat Ithnayn is the northern-most and the least studied volcanic field of the MMN line, and it has been suggested that Ithnayn represents the youngest field produced by age progressive volcanism along the MMN line. Harrat Ithnayn is thus a critical piece in the puzzle in determining the causes of the volcanic activity in the MMN line region. This research focuses primarily on investigating the age and composition of the volcanic activity at Harrat Ithnayn and how it changes through time. I apply geochronological, geochemical, and petrological methods to understand the origin and tectonic controls on volcanism in this region. I report new age determinations on 10 lava flows, one sample from the northern part of Harrat Khaybar and 9 samples from Harrat Ithnayn, by the ⁴⁰Ar-³⁹Ar laser step heating method. All ages are younger than 2 Ma and most of these lavas range in age between ~500 and 120 Ka. These ages constrain the timing and chemical variations of volcanic activity at Harrat Ithnayn. Unlike older Harrats Rahat and Khaybar, the volcanism at Harrat Ithnayn has also undergone less magmatic evolution, suggesting a lack of shallow crustal magma bodies. Similar to Harrat Hutaymah and other younger volcanic fields peripheral to the MMN line, olivine ± clinopyroxene dominated crystal fractionation at a range of upper mantle and crustal pressures, with some evidence of crustal assimilation. The new age constraints agree with the hypothesis of south-to-north volcanic progression of volcanism along the MMN line. In addition, active mantle upwelling, decompression melting and possible asthenospheric flow from the Afar mantle plume, appears to have been the source of this volcanic activity, produced from ~ 2-14% partial melting of a shallow garnet peridotite mantle source for magmas

Some Problems Concerning Quantum Channels and Entropies

This thesis describes contributions to three mathematical problems in quantum information theory. The first concerns the continuity properties of conditional entropy, which gives optimal rates for several information processing tasks including classical source compression with side information and quantum state merging. We prove a tight uniform continuity bound for the conditional Shannon entropy in terms of total variation distance. This bound may be interpreted as a continuity bound for the conditional entropy of classical states. We also include observations about a conjectured continuity bound for the conditional entropy of general quantum states. The second relates to a general class of optimization problems inspired by the following situation. Suppose the entropy of a given mixture of states is to be minimized by choosing each state subject to constraints. If the spectrum of each state is fixed, we expect that to reduce the entropy of the mixture, we should make the states less distinguishable in some sense. This situation arises for example in the recently introduced spin alignment problem, which is the main motivation for our investigation. In its original form, each state in the mixture is constrained to be a freely chosen state on a subset of n qubits tensored with a fixed state Q on each of the qubits in the complement. According to the spin alignment conjecture, the entropy of the mixture is minimized by choosing the freely chosen state in each term to be a tensor product of projectors onto a fixed maximal eigenvector of&nbsp;Q, which maximally &ldquo;aligns&rdquo; the states in the mixture. We generalize the spin alignment problem in several ways. First, instead of minimizing entropy, we consider maximizing arbitrary unitarily invariant convex functions such as Fan norms and Schatten norms. To formalize and generalize the conjectured required alignment, we define alignment as a preorder on tuples of self-adjoint operators induced by majorization. We prove the generalized conjecture for Schatten norms of integer order, for the case where the freely chosen states are constrained to be classical, and for the case where only two states contribute to the mixture and&nbsp;Q&nbsp;is proportional to a projector. The last case fits into a more general situation where we give explicit conditions for maximal alignment. The spin alignment problem has a natural &ldquo;dual&rdquo; formulation, versions of which have further generalizations that we introduce. The third is about quantum channel simulation in the specific case where the channel to be simulated is a quantum erasure channel, a task we dub quantum erasure simulation. We show that quantum erasure simulation is closely related to probabilistic quantum error correction. We examine a conjecture put forward by M.B. Hastings that says that erasure channels with erasure probability exceeding a half cannot be used to simulate better erasure channels. We use a combinatorial argument to show that the conjecture is true in the case where the encoding channel is an isometric embedding into a stabilizer code. We also show that it is true if the number of channel uses is not greater than four.</p

Knowledge, Attitudes, and Practices Regarding Diabetic Retinopathy Among Primary Health Care Physicians in Al-Hasa, Saudi Arabia

Background: Diabetic retinopathy (DR) has been shown to be the third most observed cause of visual loss in Saudi Arabia. In the Al-Hasa region in particular, the prevalence of DR has been shown to be 30%. Primary health centre (PHC) physicians play a central role in the early detection and prevention of DR. The aim of this study was to evaluate the knowledge, attitudes, and practices regarding DR of PHC physicians in Al-Hasa, Saudi Arabia.Methods: A cross-sectional descriptive study was conducted at PHCs in Al-Hasa, Saudi Arabia. A self-administered questionnaire was provided to every participant along with a consent form. Out of 71 centres in the region, 63 were included in this study. The questionnaire consisted of three sections and a total of 18 questions. Statistical analysis was carried out using the Statistical Package for the Social Sciences version 21 software program (IBM Corp., Armonk, NY, USA).Results: One hundred forty-one of 209 physicians completed the questionnaire for a response rate of 67%. The mean of overall knowledge score for all participants was 2.6 ± 1.16 points out of four points. Only 34 (24.1%) of the participants correctly referred their diabetic patients according to the guidelines of the American Academy of Ophthalmology. Additionally, only 52 (36.9%) physicians educated their patients regarding the early detection of diabetic complications.Conclusion:  The present study concluded that there exist gaps in applying the correct guidelines. Physicians' attitudes toward patient education were overall satisfactory. Further medical symposiums and workshops are warranted to teach physicians about diabetic complications and screening schedules, including DR

HRD in SMEs - a research agenda whose time has come

As can be seen from its website, and reiterated in numerous editorials (e.g., Anderson, 2017; Nimon, 2017; Reio & Werner, 2017), Human Resource Development Quarterly (HRDQ) provides a central focus on human resource development (HRD) issues as well as the means for disseminating empirical research across the breadth of the discipline. Furthermore, the listing of keywords on its website indicates the importance HRDQ places on knowing more about learning in workplace settings as it includes words and phrases such as workplace issues, workplace learning, organizational studies, and workplace performance. This is in line with general increased interest in organizational learning in recent years (Higgins & Aspinall, 2011). Therefore, it is concerning that HRDQ seldom reports on an area of workplace learning in a sector that, in many countries throughout the world, encompasses approximately 99% of all businesses, provides over 50% of employment, and can generate around 50% of national turnover (Chartered Institute for Personnel & Development [CIPD], 2015; Coetzer & Perry, 2008; European Commission, 2016; Federation of Small Businesses, 2015; Hamburg, Engert, Anke, & Marin, 2008; Matlay, 2014; Mellett & O'Brien, 2014; U.K. Parliament, 2014; U.S. Census Bureau, 2012). If you have not yet guessed, this area of learning, which is vital to economies across the globe, occurs in small and medium‐sized enterprises (SMEs). Consequently, in this editorial, we seek to explore the extent of this omission, not only in HRDQ but also in other journals, and then investigate possible reasons for this. We hope that by emphasizing both the importance of and the lack of reported research into HRD in SMEs, we will encourage further dialogue and submissions related to this important topic