Landau-Khalatnikov-Fradkin Transformations and the Fermion Propagator in Quantum Electrodynamics

We study the gauge covariance of the massive fermion propagator in three as well as four dimensional Quantum Electrodynamics (QED). Starting from its value at the lowest order in perturbation theory, we evaluate a non-perturbative expression for it by means of its Landau-Khalatnikov-Fradkin (LKF) transformation. We compare the perturbative expansion of our findings with the known one loop results and observe perfect agreement upto a gauge parameter independent term, a difference permitted by the structure of the LKF transformations.Comment: 9 pages, no figures, uses revte

Gauge Dependence of Mass and Condensate in Chirally Asymmetric Phase of Quenched QED3

We study three dimensional quenched Quantum Electrodynamics in the bare vertex approximation. We investigate the gauge dependence of the dynamically generated Euclidean mass of the fermion and the chiral condensate for a wide range of values of the covariant gauge parameter $\xi$. We find that (i) away from $\xi=0$, gauge dependence of the said quantities is considerably reduced without resorting to sophisticated vertex {\em ansatze}, (ii) wavefunction renormalization plays an important role in restoring gauge invariance and (iii) the Ward-Green-Takahashi identity seems to increase the gauge dependence when used in conjunction with some simplifying assumptions. In the Landau gauge, we also verify that our results are in agreement with those based upon dimensional regularization scheme within the numerical accuracy available.Comment: 14 pages, 11 figures, uses revte

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

Transverse Ward-Takahashi Identity, Anomaly and Schwinger-Dyson Equation

Based on the path integral formalism, we rederive and extend the transverse Ward-Takahashi identities (which were first derived by Yasushi Takahashi) for the vector and the axial vector currents and simultaneously discuss the possible anomaly for them. Subsequently, we propose a new scheme for writing down and solving the Schwinger-Dyson equation in which the the transverse Ward-Takahashi identity together with the usual (longitudinal) Ward-Takahashi identity are applied to specify the fermion-boson vertex function. Especially, in two dimensional Abelian gauge theory, we show that this scheme leads to the exact and closed Schwinger-Dyson equation for the fermion propagator in the chiral limit (when the bare fermion mass is zero) and that the Schwinger-Dyson equation can be exactly solved.Comment: 22 pages, latex, no figure

Izvala maternice i rodnice u križanih krava: prevalencija, klinička slika i liječenje preinačenim Bühnerovim postupkom upotrebom infuzijske cjevčice kao šivaćeg materijala.

Eighty-six cows presented for treatment of genital prolapse (uterine - 44 and vaginal - 42) were included in this study. Vaginal prolapse mostly occurred during advanced pregnancy and uterine prolapse following parturition. At the time of examination, most of the animals with uterine prolapse were recumbent, while those with vaginal prolapse were standing. The highest prevalence of genital prolapse was recorded in crossbred Jersey cows around the 2nd parturition during the autumn season. The number of cases with grade 1 vaginal prolapse was highest (52.38%) followed by grade 3 (33.33%) and grade 2 (14.29%) respectively. Grade 1 vaginal prolapse could be managed successfully by exogenous progesterone therapy (500 mg hydroxyprogesterone i.m. two times at weekly interval) along with hind quarter elevation in 45.45% cases (10/22); however, in the remaining 54.55% cases the prolapse was converted to grade 2. A few (27%) animals with uterine prolapse were simultaneously suffering from milk fever, dystocia and retained fetal membranes. In all the cows with grade 2 and 3 vaginal prolapse, and also those with uterine prolapse, the mass was repositioned following the standard technique under caudal epidural analgesia. A modified Bühner’s technique, using sterile infusion set tubing as suture material, was effective in retention of the mass in all the cows. Complications and disfigurement of the vulvar area were not noticed, even in cases where the suture was kept in-situ for a prolonged period.U istraživanje je bilo uključeno 86 krava: 44 s izvalom maternice, a 42 s izvalom rodnice. Izvala rodnice pretežno se javljala u visokom stupnju bređosti, a maternice nakon telenja. Za vrijeme pretrage većina krava s izvalom maternice je ležala, dok su one s izvalom rodnice stajale. Izvala spolnih organa najčešće je ustanovljena u križanih Jersey krava prilikom drugoga telenja i to u jesen. Broj slučajeva prvog stupnja izvale rodnice bio je najveći (52,38%). Slijedi broj izvala trećeg stupnja (33,33%) te drugog stupnja (14,29%). Prvi stupanj izvale rodnice bio je uspješno izliječen u 45,45% slučajeva (10/22) davanjem 500 mg hidroksiprogesterona intramuskularno dvaput tjedno uz podizanje stražnjeg dijela tijela. U ostalih 54,55% slučajeva izvala je prešla u drugi stupanj. U manjeg broja (27%) životinja s izvalom maternice bila je ustanovljena mliječna vrućica, težak porođaj i zaostajanje posteljice. U svih krava s drugim i trećim stupnjem izvale rodnice i onih s izvalom maternice, organi su bili vraćeni u normalan položaj standardnim postupkom uz kaudalnu epiduralnu anesteziju. Preinačen Bühnerov postupak upotrebom sterilne infuzijske cjevčice kao šivaćeg materijala pokazao se učinkovitim u liječenju svih krava. Komplikacije i promjene oblika stidnice nisu primijećene čak ni u slučajevima kad je šav duže vrijeme ostao in situ

A Circular Economy Framework based on Organic Wastes Upcycling for Biodiesel Production from Hermetia illucens

The present waste management practices have adverse environmental impacts at the same time costly. Approximately, 80 % of the Malaysian municipal wastes including organic wastes are usual disposed into landfills. Hence, transformation organic wastes not only providing economic and environmental benefits but has given waste a value. This study focused on synthesis of biodiesel from H. illucens pre-pupae fed with fruit waste and food waste. The objective was to evaluate interactions between the variables including catalyst loading, reaction time versus fatty acid methyl esters (FAME) yield (wt %), temperature and methanol to sample mass ratio. The response surface methodology (RSM) was used to investigate the bioconversion optimization process. Optimal biodiesel yield based on fruit waste achieved was 96.15 % at 51ºC; 8.3:1 methanol: mass ratio; 253 min and 15.1 % catalyst. Furthermore, the optimal yield obtained from the second set of optimization using lipids of pre-pupae derived from food waste was achieved at 94.63 %.  The optimum conditions for reaction temperature was 71°C, with methanol to mass ratio of 6.8:1, at reaction time of 254 min and catalyst loading of 7.0 v/v%. The properties of FAME produced were in accordance with EN 14214 and ASTM 6751 biodiesel standards

Prevalence of Dystocia in Sheep and Goats: A Study of 70 Cases (2004-2011)

A total of seventy (70) sheep and goats, suffering from dystocia were included in this retrospective study. At the time of presentation 28.57% of the animals were recumbent. More than half (54.29%) of the total cases were referred after unsuccessful handling. Significantly highest prevalence was recorded in sheep during first lambing, in winter season and in the dams carrying male fetuses (p ≤ 0.05). The average weight of male and female fetuses was 3.14 and 2.75 kg respectively. Foetal dystocia (54.29%) out-numbered maternal causes (37.14%). Both maternal and fetal causes accounted for 8.57% of the dystocia. Head deviation, fore limb flexion, breech presentation, dog sitting position and fetal monstrosities were the common fetal causes. Ring womb, the most common maternal cause of dystocia could be treated by hormones in 33.33% (5/15) cases. Fetuses could be delivered by obstetrical mutation and extraction method in 51.43% (36/70) animals and by caesarean section in the remaining cases. Fetal and dam survival was 23.08% and 94.29% respectively. The average total cost for relieving dystocia in small ruminants by obstetrical mutation and by caesarean (including cost of suture and anaesthesia) was Rs. 215.00 and 570.00 respectively. From this study, it is concluded that in order to obtain high fetal and dam survival and also to reduce the cost of treatment, sheep and goats with dystocia should be presented without undue delay

Prevalence of ultrasonography proved polycystic ovaries in North Indian women with type 2 diabetes mellitus

BACKGROUND: Polycystic ovaries (PCO) and their clinical expression (the polycystic ovary syndrome [PCOS]) as well as type 2 diabetes mellitus (T2DM) are common medical conditions linked through insulin resistance. We studied the prevalence of PCO and PCOS in women with diet and/or oral hypoglycemic treated T2DM and non-diabetic control women. DESIGN: Prospective study. METHODS: One hundred and five reproductive age group women with diet and /or oral hypoglycemic treated T2DM were the subjects of the study. Sixty age-matched non-diabetic women served as controls. Transabdominal ultrasonographic assessment of the ovaries was used to diagnose PCO. Clinical, biochemical and hormonal parameters were also noted. RESULTS: Ultrasonographic prevalence of PCO was higher in women with diabetes than in non-diabetic subjects (61.0% vs. 36.7%, P < 0.003) whereas that of PCOS was 37.1% in diabetic subjects and 25% in non-diabetic controls (P > 0.1). Diabetic women with PCO had diabetes of significantly longer duration than those without PCO (4.19±2.0 versus 2.9±1.6 yrs; p < 0.05). Among both diabetic and non-diabetic women, those with PCO had significantly higher plasma LH, LH/FSH ratio, total testosterone and androstenedione levels. CONCLUSION: This study demonstrates a higher prevalence of PCO in women with T2DM as compared to non-diabetic subjects

Enhancement of precise gene editing by the association of Cas9 with homologous recombination factors

The CRISPR-Cas9 system is used for genome editing in mammalian cells by introducing double-strand breaks (DSBs) which are predominantly repaired via non-homologous end joining (NHEJ) or to lesser extent by homology-directed repair (HDR). To enhance HDR for improving the introduction of precise genetic modifications, we tested fusion proteins of Cas9 nuclease with HDR effectors to enforce their localization at DSBs. Using a traffic-light DSB repair reporter (TLR) system for the quantitative detection of HDR and NHEJ events in human HEK cells we found that Cas9 fusions with CtIP, Rad52, and Mre11, but not Rad51C promote HDR up to twofold in human cells and significantly reduce NHEJ events. We further compared, as an alternative to the direct fusion with Cas9, two components configurations that associate CtIP fusion proteins with a Cas9-SunTag fusion or with guide RNA that includes MS2 binding loops. We found that the Cas9-CtIP fusion and the MS2-CtIP system, but not the SunTag approach increase the ratio of HDR/NHEJ 4.5–6-fold. Optimal results are obtained by the combined use of Cas9-CtIP and MS2-CtIP, shifting the HDR/NHEJ ratio by a factor of 14.9. Thus, our findings provide a simple and effective tool to promote precise gene modifications in mammalian cells

Drug resistance profile and biofilm forming potential of Pseudomonas aeruginosa isolated from contact lenses in Karachi-Pakistan

BACKGROUND: The contaminated contact lens provides Pseudomonas aeruginosa an ideal site for attachment and biofilm production. Continuous contact of the eye to the biofilm-infested lens can lead to serious ocular diseases, such as keratitis (corneal ulcers). The biofilms also prevent effective penetration of the antibiotics, which increase the chances of antibiotic resistance. METHODS: For this study, 22 Pseudomonas aeruginosa isolates were obtained from 36 contact lenses and 14 contact lens protective fluid samples. These isolates were tested against eight commonly used antibiotics using Kirby-Bauer disk diffusion method. The biofilm forming potential of these isolates was also evaluated using various qualitative and quantitative techniques. Finally, a relationship between biofilm formation and antibiotic resistance was also examined. RESULTS: The isolates of Pseudomonas aeruginosa tested were found resistant to most of the antibiotics tested. Qualitative and quantitative biofilm analysis revealed that most of the isolates exhibited strong biofilm production. The biofilm production was significantly higher in isolates that were multi-drug resistant (p < 0.0001). CONCLUSION: Our study indicates that multi-drug resistant, biofilm forming Pseudomonas aeruginosa isolates are mainly involved in contact lens associated infections. This appears to be the first report from Pakistan, which analyzes both antibiotic resistance profile and biofilm forming potential of Pseudomonas aeruginosa isolates from contact lens of the patients with contact lens associated infections