The Relevant Operators for the Hubbard Hamiltonian with a magnetic field term

The Hubbard Hamiltonian and its variants/generalizations continue to dominate the theoretical modelling of important problems such as high temperature superconductivity. In this note we identify the set of relevant operators for the Hubbard Hamiltonian with a magnetic field term.Comment: 19 pages, RevTe

New expression for the functional transformation of the vector Cramér-Rao lower bound

Assume that it is desired to estimate α = f(θ), where f(·) is an r-dimensional function. This paper derives the general expression for the functional transformation of the vector Cramér-Rao lower bound (CRLB). The derived bound is a tight lower bound on the estimation of uncoupled parameters, i.e., parameters that can be estimated separately. Unlike previous results in the literature, this new expression is not dependent on the inverse of the Fisher's information matrix (FIM) of the untransformed parameters, θ. Thus, it can be applied to scenarios where the FIM for θ is ill-conditioned or singular. Finally, as an application, the derived transformation is applied to determine the exact CRLB for estimation of channel parameters in amplify-and-forward relaying networks.This research was supported under Australian Research Council’s Discovery Projects funding scheme (project number DP110102548)

Labour Market Participation of the Elderly

Generally ageing of population is defined as the relative increase in the number of elderly. This process is the result of declining fertility and increasing life expectancy of elderly population. In today’s Pakistan, fertility has started declining and life expectancy of elderlies has been increasing and it is expected that in future both these processes will gain momentum, resulting into many fold increase in the population of elderly people [Afzal (1999); Sathar and Casterline (1998)]. These developments are expected to have adverse effects on Pakistan’s economy as support and welfare of elderly people will require additional allocation of resources. That is more so because traditionally welfare and socio-economic needs of elderly people remained the responsibility of their children especially the sons. However, the traditional extended/joint family system is fast breaking down and nuclear type of family set up is becoming more common rendering the elderly people helpless [Ali (2000)]. Moreover, in view of an increase in the incidence of poverty in Pakistan, intra-house resource distribution is also becoming scarce leading to a scenario where only productive members are the chief beneficiaries [Qureshi and Arif, (2001)]. On the other hand in Pakistan, the social sector also remained neglected and little progress has been made in the development of health, education, nutrition, housing and physical infrastructure. Moreover, social security and pension scheme for general public is also almost non-existent. Such a situation warrants development of policies especially for elderly people in general and for all those elderlies who can participate and contribute in the economic activities in particular so that economic well-being of these people is ensured.

Synchronization in Cooperative Communication Systems

Cooperative communication is an attractive solution to combat fading in wireless communication systems. Achieving synchronization is a fundamental requirement in such systems. In cooperative networks, multiple single antenna relay terminals receive and cooperatively transmit the source information to the destination. The multiple distributed nodes, each with its own local oscillator, give rise to multiple timing offsets (MTOs) and multiple carrier frequency offsets (MCFOs). Particularly, the received signal at the destination is the superposition of the relays' transmitted signals that are attenuated differently, are no longer aligned with each other in time, and experience phase rotations at different rates due to different channels, MTOs, and MCFOs, respectively. The loss of synchronization due to the presence of MTOs and MCFOs sets up the recovery of the source signal at the destination to be a very challenging task. This thesis seeks to develop estimation and compensation algorithms that can achieve synchronization and enable cooperative communication for both decode-and-forward (DF) and amplify-and-forward (AF) relaying networks in the presence of multiple impairments, i.e., unknown channel gains, MTOs, and MCFOs. In the first part of the thesis, a training-based transmission scheme is considered, in which training symbols are transmitted first in order to assist the joint estimation of multiple impairments at the destination node in DF and AF cooperative relaying networks. New transceiver structure at the relays and novel receiver design at the destination are proposed which allow for the decoding of the received signal in the presence of unknown channel gains, MTOs, and MCFOs. Different estimation algorithms, e.g., least squares (LS), expectation conditional maximization (ECM), space-alternating generalized expectation-maximization (SAGE), and differential evolution (DE), are proposed and analyzed for joint estimation of multiple impairments. In order to compare the estimation accuracy of the proposed estimators, Cramer-Rao lower bounds (CRLBs) for the multi-parameter estimation are derived. Next, in order to detect the signal from multiple relays in the presence of multiple impairments, novel optimal and sub-optimal minimum mean-square error (MMSE) compensation and maximum likelihood (ML) decoding algorithm are proposed for the destination receiver. It has been evidenced by numerical simulations that application of the proposed estimation and compensation methods in conjunction with space-time block codes achieve full diversity gain in the presence of channel and synchronization impairments. Considering training-based transmission scheme, this thesis also addresses the design of optimal training sequences for efficient and joint estimation of MTOs and multiple channel parameters. In the second part of the thesis, the problem of joint estimation and compensation of multiple impairments in non-data-aided (NDA) DF cooperative systems is addressed. The use of blind source separation is proposed at the destination to convert the difficult problem of jointly estimating the multiple synchronization parameters in the relaying phase into more tractable sub-problems of estimating many individual timing offsets and carrier frequency offsets for the independent relays. Next, a criteria for best relay selection is proposed at the destination. Applying the relay selection algorithm, simulation results demonstrate promising bit-error rate (BER) performance and realise the achievable maximum diversity order at the destination

Dyslipidemia: A Frequently Missed Disorder in Type 2 Diabetes Mellitus

Background: Dyslipidemia and type 2 diabetes mellitus a deadly combination need early diagnosis, proper management, and regular follow up.Aims of the study: Is to find the proportion, pattern, and factors related to dyslipidemia in patients with type 2 diabetes mellitus.Methodology: A cross sectional study on 74 patients with Type 2 diabetes mellitus attending the diabetes clinic in Al-Hindeya General Hospital to evaluate them for the prevalence of dyslipidemia. The patients underwent a series of investigations including serum lipid profile, fasting blood sugar, and glycated hemoglobin among others.Results: Dyslipidemia reported in 73% of the studied group. Elevated low density lipoprotein, triglycerides, total cholesterol, and reduced high density lipoprotein were noted in 28, 22, 16, and 16 patients, respectively. Patients' age above 50 years significantly associated with elevated mean TG (P-value=0.04), TC (P-value=0.001), and reduced mean HDL-C (P-value=0.004). Poor glycemic control significantly associated with elevated mean TG (P-value=0.04). Disease duration more than 5 years adversely affects mean TG level (P-value=0.01). Obesity showed highly significant correlation with elevated mean TG (P-value=0.001), TC (P-value=0.006), and LDL-C (P-value=0.001). Insulin therapy showed highly significant association with elevated mean TC (P-value=0.006) and reduced mean HDL-C (P-value=0.001). Patient gender did not affect the prevalence of dyslipidemia.  Conclusions: Dyslipidemia detected in 73% of the patients and manifested by variable combinations of elevated low density lipoproteins, triglycerides, total cholesterol, and reduced high density lipoprotein. Older age, poor glycemic control, longer disease duration, obesity, and using insulin therapy are significantly associated with dyslipidemia. Keywords: Type 2 diabetes mellitus, dyslipidemia, triglycerides, total cholesterol, high density lipoprotein cholesterol, low density lipoprotein cholesterol

Between the metropole and the postcolony: On the dynamics of rights

Recent analyses have critically evaluated the connection of abstract rights with territorial nation-states. This article extends those findings by analyzing the way discourses of rights (human, political, national) are interconnected. It is argued that the system of relations that rights establish between their norms and concrete sociopolitical practices allows rights to function as overall machinery, one that both produces and governs subjects. From this perspective, this article establishes that: (a) since rights depend for their legal guarantee on the power of nation-states, they are a normative standard which coincides with the political power of a nation-state; (b) since rights require a certain ethic from subjects in order that their exercise of rights be legally protectable, they govern subjects through inclusion, that is, by structuring fields of action in order that a certain “proper” conduct may take place; (c) since the nation-state framework with which rights are connected operates in a postcolonial order, the functioning of rights is also connected with the discursive dynamics of postcoloniality. The empirical focus of the discussion is on Pakistan. The first section focuses on the use of human rights’ discourse in order to counter drone attacks in Pakistan’s tribal belt. The conundrums that human rights in this context generate are then filled in by acknowledging “rights” of a state (i.e. political sovereignty and territorial integrity), which is the focus of second section. The third section comments on the way national and political rights correspond to the notions of “citizenship” and “belongingness,” which in turn shapes the conduct of subjects in a contextually apt manner