Evaluation of immune status in patients with breast cancer in Sokoto, Northwestern, Nigeria

Background: Breast cancer is a major public health problem especially in Sub-Saharan Africa, Nigeria inclusive. It is a leading cause of cancer- related deaths worldwide. The present study assessed the immune status of breast cancer patients using CD4+ T cell count, CD8+ T cell count, CD4+/CD8+ ratio and some leucocytes.Methods: A total of sixty nine (69) subjects that comprised of forty six (46) breast cancer patients attending the Breast Clinic of Usmanu Danfodiyo University Teaching Hospital, Sokoto and twenty three (23) age- and gender-marched apparently healthy individuals as controls were included in the study.Results: The CD4+ T cells (cell/ μl) and CD8+ T cells (cell/ μl) were enumerated using Flow Cytometric method, while CD4/CD8 ratio was calculated from the values obtained from the CD4+ T cells and CD8+ T cells. Even though, there were no significant differences in CD4+ T cells, CD8+ T cells and CD4+/CD8+ ratio based on breast cancer stages and therapy types.Conclusions: It is hereby concluded that, the monocyte counts and CD4+/CD8+ ratio were higher in breast cancer patients and this could be used to differentiate the breast cancer patients from the normal control subjects

Energy-Driven Computing: Rethinking the Design of Energy Harvesting Systems

Energy harvesting computing has been gaining increasing traction over the past decade, fueled by technological developments and rising demand for autonomous and battery-free systems. Energy harvesting introduces numerous challenges to embedded systems but, arguably the greatest, is the required transition from an energy source that typically provides virtually unlimited power for a reasonable period of time until it becomes exhausted, to a power source that is highly unpredictable and dynamic (both spatially and temporally, and with a range spanning many orders of magnitude). The typical approach to overcome this is the addition of intermediate energy storage/buffering to smooth out the temporal dynamics of both power supply and consumption. This has the advantage that, if correctly sized, the system ‘looks like’ a battery-powered system; however, it also adds volume, mass, cost and complexity and, if not sized correctly, unreliability. In this paper, we consider energy-driven computing, where systems are designed from the outset to operate from an energy harvesting source. Such systems typically contain little or no additional energy storage (instead relying on tiny parasitic and decoupling capacitance), alleviating the aforementioned issues. Examples of energy-driven computing include transient systems (which power down when the supply disappears and efficiently continue execution when it returns) and power-neutral systems (which operate directly from the instantaneous power harvested, gracefully modulating their consumption and performance to match the supply). In this paper, we introduce a taxonomy of energy-driven computing, articulating how power-neutral, transient, and energy-driven systems present a different class of computing to conventional approaches

Constraint on the QED Vertex from the Mass Anomalous Dimension γm=1\gamma_m = 1

We discuss the structure of the non-perturbative fermion-boson vertex in quenched QED. We show that it is possible to construct a vertex which not only ensures that the fermion propagator is multiplicatively renormalizable, obeys the appropriate Ward-Takahashi identity, reproduces perturbation theory for weak couplings and guarantees that the critical coupling at which the mass is dynamically generated is gauge independent but also makes sure that the value for the anomalous dimension for the mass function is strictly 1, as Holdom and Mahanta have proposed.Comment: 8 pages, LaTeX, October 199

The non-perturbative three-point vertex in massless quenched QED and perturbation theory constraints

Dong, Munczek and Roberts have shown how the full 3-point vertex that appears in the Schwinger-Dyson equation for the fermion propagator can be expressed in terms of a constrained function $W_1$ in massless quenched QED. However, this analysis involved two key assumptions: that the fermion anomalous dimension vanishes in the Landau gauge and that the transverse vertex has a simplified dependence on momenta. Here we remove these assumptions and find the general form for a new constrained function $U_1$ that ensures the multiplicative renormalizability of the fermion propagator non-perturbatively. We then study the restriction imposed on $U_1$ by recent perturbative calculations of the vertex and compute its leading logarithmic expansion. Since $U_1$ should reduce to this expansion in the weak coupling regime, this should serve as a guide to its non-perturbative construction. We comment on the perturbative realization of the constraints on $U_1$.Comment: 18 pages, Latex, 2 figure

Vacuum Polarization and Dynamical Chiral Symmetry Breaking: Phase Diagram of QED with Four-Fermion Contact Interaction

We study chiral symmetry breaking for fundamental charged fermions coupled electromagnetically to photons with the inclusion of four-fermion contact self-interaction term. We employ multiplicatively renormalizable models for the photon dressing function and the electron-photon vertex which minimally ensures mass anomalous dimension = 1. Vacuum polarization screens the interaction strength. Consequently, the pattern of dynamical mass generation for fermions is characterized by a critical number of massless fermion flavors above which chiral symmetry is restored. This effect is in diametrical opposition to the existence of criticality for the minimum interaction strength necessary to break chiral symmetry dynamically. The presence of virtual fermions dictates the nature of phase transition. Miransky scaling laws for the electromagnetic interaction strength and the four-fermion coupling, observed for quenched QED, are replaced by a mean-field power law behavior corresponding to a second order phase transition. These results are derived analytically by employing the bifurcation analysis, and are later confirmed numerically by solving the original non-linearized gap equation. A three dimensional critical surface is drawn to clearly depict the interplay of the relative strengths of interactions and number of flavors to separate the two phases. We also compute the beta-function and observe that it has ultraviolet fixed point. The power law part of the momentum dependence, describing the mass function, reproduces the quenched limit trivially. We also comment on the continuum limit and the triviality of QED.Comment: 9 pages, 10 figure

Biological activities of a new compound isolated from the aerial parts of Vitex agnus castus L.

A new compound trivially named vitexcarpan was isolated from the ethyl acetate fraction of Vitex agnus castus. The structure of compound was elucidated with the help of spectroscopic techniques: 13C NMR, 1H NMR, heteronuclear multiple bond correlation (HMBC), heteronuclear multiple quantum coherence (HMQC), nuclear overhauser effect spectroscopy (NOESY) and correlation spectroscopy (COSY). The isolated compound was screened for possible urease, chymotrypsin and anti-inflammatory activities. The results showed that the compound possess moderate inhibitory activity against urease (43.3 %) and chymotrypsin (39.8 %) enzymes. Vitexcarpan also showed moderate (48 %) in vitro antiinflammatory activity using activated human neutrophils.Keywords: Vitex agnus castus, vitexcarpan urease, chymotrypsin, anti-inflammator

The nonperturbative propagator and vertex in massless quenched QED_d

It is well known how multiplicative renormalizability of the fermion propagator, through its Schwinger-Dyson equation, imposes restrictions on the 3-point fermion-boson vertex in massless quenched quantum electrodynamics in 4-dimensions (QED$_4$). Moreover, perturbation theory serves as an excellent guide for possible nonperturbative constructions of Green functions. We extend these ideas to arbitrary dimensions $d$. The constraint of multiplicative renormalizability of the fermion propagator is generalized to a Landau-Khalatnikov-Fradkin transformation law in $d$-dimensions and it naturally leads to a constraint on the fermion-boson vertex. We verify that this constraint is satisfied in perturbation theory at the one loop level in 3-dimensions. Based upon one loop perturbative calculation of the vertex, we find additional restrictions on its possible nonperturbative forms in arbitrary dimensions.Comment: 13 pages, no figures, latex (uses IOP style files

Longitudinal and transverse fermion-boson vertex in QED at finite temperature in the HTL approximation

We evaluate the fermion-photon vertex in QED at the one loop level in Hard Thermal Loop approximation and write it in covariant form. The complete vertex can be expanded in terms of 32 basis vectors. As is well known, the fermion-photon vertex and the fermion propagator are related through a Ward-Takahashi Identity (WTI). This relation splits the vertex into two parts: longitudinal (Gamma_L) and transverse (Gamma_T). Gamma_L is fixed by the WTI. The description of the longitudinal part consumes 8 of the basis vectors. The remaining piece Gamma_T is then written in terms of 24 spin amplitudes. Extending the work of Ball and Chiu and Kizilersu et. al., we propose a set of basis vectors T^mu_i(P_1,P_2) at finite temperature such that each of these is transverse to the photon four-momentum and also satisfies T^mu_i(P,P)=0, in accordance with the Ward Identity, with their corresponding coefficients being free of kinematic singularities. This basis reduces to the form proposed by Kizilersu et. al. at zero temperature. We also evaluate explicitly the coefficient of each of these vectors at the above-mentioned level of approximation.Comment: 13 pages, uses RevTe

Oštećenja u aluminiju proizvedena zračenjem iz CO2 i Nd:YAG lasera

The change in the electrical properties of pure aluminium (Al 99.999%) after exposure to CO2 (energy = 2.5 J/pulse, wavelength = 10.6 µm, pulse duration = 200 nsec) and Nd:YAG (energy = 10 mJ/pulse, wavelength = 1.06 µm and pulse duration = 12 nsec) laser radiation is investigated. The samples were exposed to laser radiations for different numbers of pulses. The change in electrical characteristics of Al is studied under different ambient conditions, after irradiating the samples in air, vacuum and hydrogen at different pressures. After exposure, the electrical conductivity of Al is measured by the four probe method. The electrical conductivity decreases with increasing number of pulses. The damage in air and in hydrogen is more pronounced than in vacuum which can be attributed to collisionnal sputtering of Al by plasma ions of air molecules and hydrogen, respectively. The change in the conductivity in hydrogen is pressure-dependent. Some theoretical considerations are also made, e.g. the phonon speed in Al during the photon interaction, minimal melting and evaporation energy per volume, damage threshold energy, penetration depth, the mass of heated volume and average temperature rise at the Al surface during laser irradiation.Proučavamo promjene električnih svojstava čistog aluminija (Al 99.999%) nakon obasjavanja CO2 (energija = 2.5 J/puls, valna duljina = 10.6 µm, trajanje pulsa = 200 nsec) i Nd:YAG (energija = 10 mJ/puls, valna duljina = 1.06 µm, trajanje pulsa = 12 nsec) laserima. Uzorci su izloženi različitim brojevima pulseva. Proučavali smo promjene električne vodljivosti Al s uzorcima u zraku, vakuumu i u vodiku. Nakon obasjavanja mjerili smo električnu vodljivost metodom četiriju spojišta. Električna se vodljivost smanjuje nakon povećanog broja pulseva. Oštećenja u zraku i vodiku veća su nego u vakuumu, što se pripisuje sudarnom rasprašivanju Al ionima molekula zraka odnosno vodika u plazmi. Promjena vodljivosti uzoraka obasjanih u vodiku ovisna je o tlaku. Razmotrili smo neke teorijske rezultate, npr. fononsku brzinu u Al tijekom obasjavanja, minimalnu energiju taljenja i isparavanja po jedinici volumena, energijski prag oštećenja, dubinu prodiranja, masu zagrijanog volumena i prosječno povećanje temperature površine Al tijekom obasjavanja