Anomalously large capacitance of a plane capacitor with a two-dimensional electron gas

In electronic devices where a two-dimensional electron gas (2DEG) comprises one or both sides of a plane capacitor, the resulting capacitance $C$ can be larger than the "geometric capacitance" $C_g$ determined by the physical separation $d$ between electrodes. This larger capacitance is known to result from the Coulomb correlations between individual electrons within the low density 2DEG, which lead to a negative thermodynamic density of states (negative compressibility). Experiments on such systems generally operate in the regime where the average spacing between electrons $n^{-1/2}$ in the 2DEG is smaller than $d$, and these experiments observe $C > C_g$ by only a few percent. A recent experiment [1], however, has observed $C$ larger than $C_g$ by almost 40% while operating in the regime $nd^2 << 1$. In this paper we argue that at $nd^2 << 1$ correlations between the electronic charge of opposite electrodes become important. We develop a theory of the capacitance for the full range of $nd^2$. We show that, in the absence of disorder, the capacitance can be $4d/a$ times larger than the geometric value, where $a << d$ is the electron Bohr radius. Our results compare favorably with the experiment of Ref. [1] without the use of adjustable parameters.Comment: 8 pages, 6 figures; revised discussion of the zero density limit; some typos fixe

Subjects, Agents, or Collectives? The Discourse of Youth and Philosophy

The present paper argues that the term "youth", which is traditionally used to refer both to young people of a certain age bracket and to a time of life between childhood and maturity has acquired distinctive yet contradictory meanings since the 19th century, and that the category of people, individuals, or persons that the concept describes or purports to analyze (the so-called young people, teenagers, pubescents, adolescents) may be regarded as subjects in the philosophical sense of being persons capable of intentional behaviour and to whom intentional predicates (beliefs and desires) can be ascribed but not, however, as a collective agent, with the capacity for goal-directed activity (such as, for example, political, social, or national transformation), in spite of the shift in the use of the concept from a singular to a collective noun. The paper argues further that the term "youth" is a vacuous concept, and thus lacks any philosophic or analytic significance or explanatory value in social theory and, especially, in philosophy, and that the discourse of youth which deploys the concept can only sustain the "politics of collective singularity" whereby a singular or a single collective subject or a parasitic structure usurps, or feeds on, the activity and capacity of empirical subjects (young people). The paper draws out the philosophic and practical-political implications of its central arguments - namely that young people, teenagers, pubescents, or adolescents those presumably described by the collective noun, "youth", do not, and cannot, articulate a coherent group - or age-based beliefs, desires, reasons, and action; cannot represent (or be the collective agency of) definite, historically-specific political-economic interests or relations in society; and, that, to the same extent, cannot be an agency of, or for; and indeed cannot be mobilized form; any form of enduring political action or social or national transformation

The meaning of different forms of structural myocardial injury, immune response and timing of infarct necrosis and cardiac repair

Although a decline in the all-cause and cardiac mortality rates following myocardial infarction (MI) during the past 3 decades has been reported, MI is a major cause of death and disability worldwide. From a pathological point of view MI consists in a particular myocardial cell death due to prolonged ischemia. After the onset of myocardial ischemia, cell death is not immediate, but takes a finite period of time to develop. Once complete myocytes’ necrosis has occurred, a process leading to a healed infarction takes place. In fact, MI is a dynamic process that begins with the transition from reversible to irreversible ischemic injury and culminates in the replacement of dead myocardium by a fibrous scar. The pathobiological mechanisms underlying this process are very complex, involving an inflammatory response by several pathways, and pose a major challenge to ability to improve our knowledge. An improved understanding of the pathobiology of cardiac repair after MI and further studies of its underlying mechanisms provide avenues for the development of future strategies directed toward the identification of novel therapies. The chronologic dating of MI is of great importance both to clinical and forensic investigation, that is, the ability to create a theoretical timeline upon which either clinicians or forensic pathologists may increase their ability to estimate the time of MI. Aging of MI has very important practical implications in clinical practice since, based on the chronological dating of MI, attractive alternatives to solve therapeutic strategies in the various phases of MI are developing

Democracy and National Development: A Focus on Nigeria

Democracy is a government form based on the general consent, is seen to becoming common in global nations; and that if the tenet is followed it facilitates national development. This study used the content analysis method to examine democracy in Nigeria and national development. It was found that some pre-colonial administrations in Nigeria had embraced democratic tenets before the colonials master came; the difference, however, border on structural arrangements. It was found that the version of western democracy has not adapted the Nigeria environment making its practice difficult and also difficult to attain national development. It was also found that the phase Nigeria democracy passed, especially, during the military regimes has not provided opportunities for development. The ethnic diversity of Nigeria and inabilities of leadership to manage it was found to pose legislative influence on democracy and national development. It was found that Nigeria environment lacks the absorptive capacity to accommodate liberal democracy considering the death of institutions and the skewed electoral process. It was found that absence of effective democracy in Nigeria disarticulated the pre-colonial democratic structure, and the exclusivist approach to liberal democracy and the rule of the game, manifest in incessant agitations, militancy, insurgency, banditry, and general underdevelopment. It was also suggested that a change in leadership approach is necessary, more importantly, to allow a breath of democratic participation in policy-making for national development. It was also recommended that all forms of discriminations are addressed and that constitutionalism should be upheld

The therapeutic potential of melatonin on neuronal function during normal ageing in male rats

Background: Ageing is a common factor in the onset neuronal dysfunction and neurodegenerative diseases. Serum level of melatonin (N-acetyl-5-methoxytryptamine), a free radical scavenger, reduces significantly during normal ageing and in neurodegeneration. Methods: To test the therapeutic potential of melatonin on function during normal ageing, we carried out an assessment of neuronal function in six months, nine months, twelve months and twenty-four months old male Sprague Dawley (SD) rats with 0.1mg/kg exogenous melatonin. Data was analyzed using one way analysis of variance (ANOVA) and Student-Knewman Keuls post-hoc test. Results: In six months old SD rats, melatonin treatment for two months restored motor function in the Chimney test. Furthermore, melatonin administration improved exploratory behavior and motor activity in ageing rats in the Elevated plus Maze (EPM) task. Finally, only 33% of melatonin treated rats had died at the termination of the experiment while all controls had 100% mortality. Conclusion: Melatonin may be a beneficial therapeutic agent to improve neuronal function during normal ageing.Keywords: Melatonin, neuronal function, motor function, normal agein

Effects of Intra-Row Spacing on Herbage Yields of Two Groundnut (Arachis hypogaea L.) Varieties in Sokoto, Semi-Arid Zone, Nigeria

Field experiments were conducted during 2009 and 2010 rainy seasons at the Dry Land Teaching and Research Farm of the Usmanu Danfodiyo University, Sokoto to study the effects of intra-spacing on herbage yields of two groundnut (Arachis hypogaea L.) varieties in Sokoto, in the semi-arid zone of Nigeria. Treatments consisted of factorial combinations of three intra-row spacing (10, 20 and 30 cm) and two groundnut varieties (Ex-Dakar and RMP-12) laid out in a randomized complete block design replicated three times. Data was collected in respect of haulm and total dry matter yield. Results revealed that, the closest intra-row spacing (10 cm) significantly (P&lt;0.05) produced higher herbage yield than the wider intra-row spacing (20 cm and 30 cm) Ex- Dakar was superior to RMP-12 in terms of total dry matter, while RMP-12 was superior to Ex-Dakar in terms of haulm yield. The closest intra-row spacing (10 cm) was the best for optimum herbage yield production.Key wards: Groundnut, yield, Intra-row spacing, variety and Semi- arid

Growth and yield response of irrigated maize (Zea mays L.) to the application of different rates of inorganic fertilizer and poultry manure

The growth and yield response of irrigated maize (Zea mays L.) under varying levels of inorganic fertilizer and poultry manure was evaluated during 2019/2020 dry season at two locations (Teaching and Research Farm of the Department of Crop Science, Kaduna State University, Kafanchan Campus and Kadawa, Irrigation Research Farm of Ahmadu Bello University Zaria, Nigeria) using a complete randomized block design with three replications. The experimental treatments consist of varying quantities of poultry manure: 1.5, 3.0, and 4.5 tonnes per hectare that were incorporated in to the soil along with four levels of inorganic fertilizer 0, 100, 120, and 140 kg N ha-1 . The results of the field trials showed that all growth and yield parameters were significantly affected by poultry manure rate in both Kafanchan and Kadawa. However, the effect of poultry manure on maize plant height and cob diameter was not significant in Kafanchan. The application of inorganic fertilizer had a positive and significant influence on all maize growth and yield attributes in both locations. Irrigated maize yield showed significant increase with increasing quantities of inorganic fertilizer and poultry manure in both Kafanchan and Kadawa. The results of the field trial indicated that a combination of 120 kg N ha-1 inorganic fertilizer and 3.0 t ha-1 poultry manure is desirable for optimum irrigated maize yield in Kafanchan and Kadawa. Keywords: Maize, Irrigation, Poultry manure, Mineral fertilizer; Grain yiel