Duality symmetry and the form fields of M-theory

In previous work we derived the topological terms in the M-theory action in terms of certain characters that we defined. In this paper, we propose the extention of these characters to include the dual fields. The unified treatment of the M-theory four-form field strength and its dual leads to several observations. In particular we elaborate on the possibility of a twisted cohomology theory with a twist given by degrees greater than three.Comment: 12 pages, modified material on the differentia

M-theory and Characteristic Classes

In this note we show that the Chern-Simons and the one-loop terms in the M-theory action can be written in terms of new characters involving the M-theory four-form and the string classes. This sheds a new light on the topological structure behind M-theory and suggests the construction of a theory of `higher' characteristic classes.Comment: 8 pages. Error in gravitational term fixed; minor corrections; reference and acknowledgement adde

The Elliptic curves in gauge theory, string theory, and cohomology

Elliptic curves play a natural and important role in elliptic cohomology. In earlier work with I. Kriz, thes elliptic curves were interpreted physically in two ways: as corresponding to the intersection of M2 and M5 in the context of (the reduction of M-theory to) type IIA and as the elliptic fiber leading to F-theory for type IIB. In this paper we elaborate on the physical setting for various generalized cohomology theories, including elliptic cohomology, and we note that the above two seemingly unrelated descriptions can be unified using Sen's picture of the orientifold limit of F-theory compactification on K3, which unifies the Seiberg-Witten curve with the F-theory curve, and through which we naturally explain the constancy of the modulus that emerges from elliptic cohomology. This also clarifies the orbifolding performed in the previous work and justifies the appearance of the w_4 condition in the elliptic refinement of the mod 2 part of the partition function. We comment on the cohomology theory needed for the case when the modular parameter varies in the base of the elliptic fibration.Comment: 23 pages, typos corrected, minor clarification

Surgical itinerary in parathyroid hyperfunction: 63 cases operated on

Universitatea de Medicină și Farmacie ”Gr. T. Popa”, Iași, Clinica IV-a Chirurgie, Clinica V-a Pediatrie, Al XI-lea Congres al Asociației Chirurgilor „Nicolae Anestiadi” din Republica Moldova și cea de-a XXXIII-a Reuniune a Chirurgilor din Moldova „Iacomi-Răzeșu” 27-30 septembrie 2011Introducere: Multiplele aspecte etiopatogenice și anatomo-clinice ale hiperparatiroidismului (HP): pri-mar (HPP), renal (HPR), familial, din NEM etc. constituie o patologie care realizează o continuă provocare. În afara fenotipului și simptomatologiei polimorfe, a noilor achiziții diagnostice și terapeutice, frapează contrastul dintre incidența/prevalența sindromului în creștere în tările dezvoltate – mai ales pe seama observațiilor asimptomatice - și seriile limitate numeric sau cazurile izolate cu manifestări “istorice”, publicate în literatura națiunilor “în tranziție” sau subdezvoltate. Material și metoda: Din 1986 în clinica noastră au fost operate 63 observații de HP: 20 HPP – adenoame =17, carcinoame=2, paratiromatoza=1 și 43 HPR – HP secundar (HPS)=23 și tertiar=20. Am înregistrat 44 femei și 19 bărbati (raport 2,3/1) cu limite de vârstă 15 – 67 (medie 47) ani. Diagnosticul și indicația chirurgicală au fost stabilite clinic prin prezența suferinței renale – urolitiaza multipla sau recidivata în HPP – insuficiența renală cronică în regim de hemodializa în HPR, sindrom osos manifest – osteoporoza, dureri osoase, chisturi și fracturi, manifestări neuromusculare, psihonevrotice, digestive și cardiovasculare în ambele varietăți. Datele de laborator au obiectivat valori anormale ale calciului seric total și ionizat, fosforului și fosfatazei alcaline și în special ale iPTH iar explorarile localizatoare au inclus ultrasonografia – mai puțin concludentă în leziunile multiglandulare și mai recent scintigrafia cu 99mTc-tetrophosmin. Rezultate: Toate cazurile au fost operate practicându-se exereza simplă în 17 adenoame și “în bloc” cu lobul tiroidian ipsilateral în două cancere (unul fiind o recidivă la 4 ani după indepărtarea unui adenom), într-un adenom chistic intratiroidian ca și în cazul de paratiromatoza (de asemenea recidiva după exere-za extra muros a unui adenom). În observațiile de HPR au fost executate 24 paratiroidectomii subtotale (în 20 observatii reușindu-se exereza standard a 3 si ½ glande, în rest indepartandu-se 3 sau doar 2 paratiroide) si respectiv 19 paratiroidectomii totale (6 cu autotransplant glandular și 13 simple). Din considerente tactice sau pentru leziuni asociate explorarea/exereza chirurgicală a fost extinsă la tiroida (29 cazuri) sau timus (20 cazuri). Examenul anatomopatologic a precizat diagnosticul final în toate obser-vațiile. Rezultatele imediate și în timp au fost bune în special în HPP. Nu au fost hipocalcemii persistente chiar în cazul paratiroidectomiilor extinse dar am notat o paralizie recurentială, un hematom al lojei și recidiva în două cazuri de autotransplant antibrahial ca și cea a unui cancer la 4 ani după extirparea unui adenom (leziune noua ?). Concluzii: Paratiroidectomia – cu rafinamentele sale recente: minim invazivă, endoscopică sau asistată robotic – este singurul tratament eficace și definitiv în HPP și constituie o terapie simptomatică impor- tantă, deși suboptimal, în cazurile de HPR (a căror tratament ideal este transplantul renal). Exerezele paratiroidiene trebuie practicate doar de specialiști antrenați în această chirurgie.Background: Hyperparathyroidism (HP) is a constantly evolving entity with multiple clinical varieties i.e.: primary (HPP), renal (HPR), familial, in MEN etc., proteiform phenotype and symptomatology, continous modernizing diagnosis and therapeutic methods and striking differences in epidemiology between developed nations and the 3rd world’s or “in transition” countries. Material and methods: The study population comprised 63 patients with HP operated on from 1986 in our clinic. There were 20 cases with PHP (17 adenomas, 2 carcinomas and one parathyromatosis) and 43 cases with RHP (23 secondary and 20 tertiary). The series included 44 women and 19 men (ratio 2,3/1), aged 15-67 (range 47) years. As a rule the documentation of signs and symptoms as well as recording of the surgical indications were consistently thorough. The presence of multiple and recurrent urolithiasis in HPP and renal failure on hemodialysis in HPR as well as bone, muscular, neuropsychiatric, digestive and cardiovascular manifestation in both syndromes are constantly described. Laboratory data indicated abnormally levels of serum calcium, phosphorus, alkaline phosphatase but especially of the iPTH. Localisation procedures included ultrasonography less valuable for multiglandular lesions and recently 99mTc-tetrophosmin scan. Results: All the cases were operated on: 17 simple exeresis for adenomas and 4 “en bloc” resections to-gether with the thyroid lobe for two carcinomas, intrathyroid cystic adenoma and parathyromatosis one case each. In HPR 20 patients underwent standard subtotal parathyroidectomy (3 and ½ glands) but in 3 cases only 3 or even 2 glands were founded and 19 total parathyroidectomy respectively (6 with auto- transplantation). Thyroid (n=29) and thymus (20) resections were practiced for associated lesions or tac- tical reasons. Pathology established the final diagnosis. Immediate and late results were good especially in HPP. Persistent hypocalcemia was not encountered even in extended resections but we avow a cervi-cal hematoma,a recurrent laryngeal nerve palsy, two antibrahial recurrences and a carcinoma developed four years after resection of an adenoma (new lesion ?). Conclusions: Parathyroidectomy with its recent refinements in minimally invasive, endoscopic, video- and robotic techniques constitutes the gold standard therapy for HPP and still remains the only permanently effective method offering an improved quality of life in HPR. These operations must be done by high-specialised surgeons

Fractional two-branes, toric orbifolds and the quantum McKay correspondence

We systematically study and obtain the large-volume analogues of fractional two-branes on resolutions of orbifolds C^3/Z_n. We study a generalisation of the McKay correspondence proposed in hep-th/0504164 called the quantum McKay correspondence by constructing duals to the fractional two-branes. Details are explicitly worked out for two examples -- the crepant resolutions of C^3/Z_3 and C^3/Z_5.Comment: 34 pages, 2 figures, LaTeX (JHEP3 style); (v2) typos corrected; (v3) sec 3 reorganise

On D0-branes in Gepner models

We show why and when D0-branes at the Gepner point of Calabi-Yau manifolds given as Fermat hypersurfaces exist.Comment: 22 pages, substantial improvements in sections 2 and 3, references added, version to be publishe

Meta-Stable Dynamical Supersymmetry Breaking Near Points of Enhanced Symmetry

We show that metastable supersymmetry breaking is generic near certain enhanced symmetry points of gauge theory moduli spaces. Our model consists of two sectors coupled by a singlet and combines dynamical supersymmetry breaking with an O'Raifeartaigh mechanism in terms of confined variables. All relevant mass parameters, including the supersymmetry breaking scale, are generated dynamically. The metastable vacua appear as a result of a balance between non-perturbative and perturbative quantum effects along a pseudo-runaway direction.Comment: 27 pages, harvmac, 6 figure

Fractional Branes in Non-compact Type IIA Orientifolds

We study fractional D-branes in the Type-IIA theory on a non-compact orientifold of the orbifold C^3/Z_3 in the boundary state formalism. We find that the fractional D0-branes of the orbifold theory become unstable due to the presence of a tachyon, while there is a stable D-instanton whose tachyon gets projected out. We propose that the D-instanton is obtained after tachyon condensation. We evidence this by calculating the Whitehead group of the Abelian category of objects corresponding to the boundary states as being isomorphic to Z_2.Comment: 29 pages, Latex2e minor corrections. references updated. Version accepted in JHE

BPS branes in discrete torsion orbifolds

We investigate D-branes in a Z_3xZ_3 orbifold with discrete torsion. For this class of orbifolds the only known objects which couple to twisted RR potentials have been non-BPS branes. By using more general gluing conditions we construct here a D-brane which is BPS and couples to RR potentials in the twisted and in the untwisted sectors.Comment: 20 pages, LaTe