625 research outputs found
Monopoles and flux strings from SU(2) adjoint scalars
We construct, in an SU(2) gauge theory with two adjoint scalars, flux strings
with monopoles attached at the ends. One scalar breaks SU(2) to U(1) and
produces monopoles, the other then breaks the U(1) and produces strings.
Dualizing, we write the theory in terms of effective string variables and show
that the flux in the string is exactly saturated by the monopoles at the ends.Comment: 12 pp. v2: added several references and reworded some statement
Quantized Skyrmion Fields in 2+1 Dimensions
A fully quantized field theory is developped for the skyrmion topological
excitations of the O(3) symmetric CP-Nonlinear Sigma Model in 2+1D. The
method allows for the obtainment of arbitrary correlation functions of quantum
skyrmion fields. The two-point function is evaluated in three different
situations: a) the pure theory; b) the case when it is coupled to fermions
which are otherwise non-interacting and c) the case when an electromagnetic
interaction among the fermions is introduced. The quantum skyrmion mass is
explicitly obtained in each case from the large distance behavior of the
two-point function and the skyrmion statistics is inferred from an analysis of
the phase of this function. The ratio between the quantum and classical
skyrmion masses is obtained, confirming the tendency, observed in semiclassical
calculations, that quantum effects will decrease the skyrmion mass. A brief
discussion of asymptotic skyrmion states, based on the short distance behavior
of the two-point function, is also presented.Comment: Accepted for Physical Review
Curcumin affects HSP60 folding activity and levels in neuroblastoma cells
The fundamental challenge in fighting cancer is the development of protective agents able to interfere with the classical pathways of malignant transformation, such as extracellular matrix remodeling, epithelial\u2013mesenchymal transition and, alteration of protein homeostasis. In the tumors of the brain, proteotoxic stress represents one of the main triggering agents for cell transformation. Curcumin is a natural compound with anti-inflammatory and anti-cancer properties with promising potential for the development of therapeutic drugs for the treatment of cancer as well as neurodegenerative diseases. Among the mediators of cancer development, HSP60 is a key factor for the maintenance of protein homeostasis and cell survival. High HSP60 levels were correlated, in particular, with cancer development and progression, and for this reason, we investigated the ability of curcumin to affect HSP60 expression, localization, and post-translational modifications using a neuroblastoma cell line. We have also looked at the ability of curcumin to interfere with the HSP60/HSP10 folding machinery. The cells were treated with 6, 12.5, and 25 \ub5M of curcumin for 24 h, and the flow cytometry analysis showed that the compound induced apoptosis in a dose-dependent manner with a higher percentage of apoptotic cells at 25 \ub5M. This dose of curcumin-induced a decrease in HSP60 protein levels and an upregulation of HSP60 mRNA expression. Moreover, 25 \ub5M of curcumin reduced HSP60 ubiquitination and nitration, and the chaperonin levels were higher in the culture media compared with the untreated cells. Furthermore, curcumin at the same dose was able to favor HSP60 folding activity. The reduction of HSP60 levels, together with the increase in its folding activity and the secretion in the media led to the supposition that curcumin might interfere with cancer progression with a protective mechanism involving the chaperonin
Toxoplasma gondii in raw milk from Sicily
Toxoplasma gondii tachyzoites shed in milk of infected animals are a potential source of human infection often underestimated. Furthermore, limited risk assessment studies have been carried out to evaluate the transmission of toxoplasmosis by milk consumption. In this frame the availability of few and often not validated analytical methods can be a major shortcoming when investigating the extent of milk contamination and the parasite viability. To address the issue, 1381 samples of raw milk from unknown sero-status cows, donkeys, sheep and goats were examined for the detection of T. gondii DNA by a real time PCR method targeting the 529bp repeating element. The protozoan DNA was detected in 67 samples of cowâs milk (4,93% and 35% individual and herd prevalence respectively) and in one sample of donkey milk. Allegedly, on farm cats cohabitation as well as extensive management in the cattle farms that tested positive, can be accounted for environmental loading and transmission of T. gondii oocysts that are the unique sources of infection for milk-producing animals. Food safety-wise, results are noteworthy since recently raw cowâs milk consumption has become increasingly popular with the spread of automatic raw milk vending machines. Albeit heating treatment before consumption is mandatory for consumers, neglect of this requirement cannot be ruled out and could lead the way for foodborne infection. This is particularly true in view of evidences that T. gondii tachyzoites in experimentally spiked cowâs milk samples could be able to survive in gastric fluids for long enough (1 h) before reaching the intestine and infect the host
Relativistic particle dynamics in D=2+1
We propose a SUSY variant of the action for a massless spinning particles via
the inclusion of twistor variables. The action is constructed to be invariant
under SUSY transformations and -reparametrizations even when an
interaction field is including. The constraint analysis is achieved and the
equations of motion are derived. The commutation relations obtained for the
commuting spinor variables show that the particle states have
fractional statistics and spin. At once we introduce a possible massive term
for the non-interacting model.Comment: 11 page
Isotopic labelling reveals the efficient adaptation of wheat root TCA cycle flux modes to match carbon demand under ammonium nutrition
Proper carbon (C) supply is essential for nitrogen (N) assimilation especially when plants are grown under ammonium (NH4+) nutrition. However, how C and N metabolic fluxes adapt to achieve so remains uncertain. In this work, roots of wheat (Triticum aestivum L.) plants grown under exclusive NH4+ or nitrate (NO3â) supply were incubated with isotope-labelled substrates (15NH4+, 15NO3â, or [13C]Pyruvate) to follow the incorporation of 15N or 13C into amino acids and organic acids. Roots of plants adapted to ammonium nutrition presented higher capacity to incorporate both 15NH4+ and 15NO3â into amino acids, thanks to the previous induction of the NH4+ assimilative machinery. The 15N label was firstly incorporated into [15N]Gln vĂa glutamine synthetase; ultimately leading to [15N]Asn accumulation as an optimal NH4+ storage. The provision of [13C]Pyruvate led to [13C]Citrate and [13C]Malate accumulation and to rapid [13C]2-OG consumption for amino acid synthesis and highlighted the importance of the anaplerotic routes associated to tricarboxylic acid (TCA) cycle. Taken together, our results indicate that root adaptation to ammonium nutrition allowed efficient assimilation of N thanks to the promotion of TCA cycle open flux modes in order to sustain C skeleton availability for effective NH4+ detoxification into amino acids
Photoperiod Manipulation Reveals a Light-Driven Component to Daily Patterns of Ventilation in Male C57Bl/6J Mice
Obstructive sleep apnea is a common sleep disorder that increases risk for cardiovascular disease and mortality. The severity of sleep-disordered breathing in obstructive sleep apnea patients fluctuates with the seasons, opening the possibility that seasonal changes in light duration, or photoperiod, can influence mechanisms of breathing. Photoperiod can have profound effects on internal timekeeping and can reshape metabolic rhythms in mammals. While the daily rhythm in ventilation is largely shaped by the metabolic rate, less is known about whether ventilatory rhythms are altered in accordance with metabolism under different photoperiods. Here, we investigate the relationship between ventilation and metabolism under different photoperiods using whole-body plethysmography and indirect calorimetry. We find that the daily timing of ventilation is chiefly synchronized to dark onset and that light cues are important for maintaining daily ventilatory rhythms. Moreover, changes in ventilatory patterns are not paralleled by changes in oxygen consumption, energy expenditure, or respiratory exchange rate under different photoperiods. We conclude that ventilatory patterns are not only shaped by the metabolic rate and circadian timing but are also influenced by other light-driven factors. Collectively, these findings have clinical implications for the seasonal variations in sleep-disordered breathing found in individuals with obstructive sleep apnea
The Whitham Deformation of the Dijkgraaf-Vafa Theory
We discuss the Whitham deformation of the effective superpotential in the
Dijkgraaf-Vafa (DV) theory. It amounts to discussing the Whitham deformation of
an underlying (hyper)elliptic curve. Taking the elliptic case for simplicity we
derive the Whitham equation for the period, which governs flowings of branch
points on the Riemann surface. By studying the hodograph solution to the
Whitham equation it is shown that the effective superpotential in the DV theory
is realized by many different meromorphic differentials. Depending on which
meromorphic differential to take, the effective superpotential undergoes
different deformations. This aspect of the DV theory is discussed in detail by
taking the N=1^* theory. We give a physical interpretation of the deformation
parameters.Comment: 35pages, 1 figure; v2: one section added to give a physical
interpretation of the deformation parameters, one reference added, minor
corrections; v4: minor correction
Loop-Corrected Compactifications of the Heterotic String with Line Bundles
We consider the E8 x E8 heterotic string theory compactified on Calabi-Yau
manifolds with bundles containing abelian factors in their structure group.
Generic low energy consequences such as the generalised Green-Schwarz mechanism
for the multiple anomalous abelian gauge groups are studied. We also compute
the holomorphic gauge couplings and induced Fayet-Iliopoulos terms up to
one-loop order, where the latter are interpreted as stringy one-loop
corrections to the Donaldson-Uhlenbeck-Yau condition. Such models generically
have frozen combinations of Kaehler and dilaton moduli. We study concrete
bundles with structure group SU(N) x U(1)^M yielding quasi-realistic gauge
groups with chiral matter given by certain bundle cohomology classes. We also
provide a number of explicit tadpole free examples of bundles defined by exact
sequences of sums of line bundles over complete intersection Calabi-Yau spaces.
This includes one example with precisely the Standard Model gauge symmetry.Comment: 47 pages, 6 figures, LaTeX, v2: stability discussion in sect. 2.1
slightly extended, refs. added, v3: normalization of Green-Schwarz term
correcte
Adding flavor to AdS/CFT
Coupling fundamental quarks to QCD in the dual string representation
corresponds to adding the open string sector. Flavors therefore should be
represented by space-time filling D-branes in the dual 5d closed string
background. This requires several interesting properties of D-branes in AdS.
D-branes have to be able to end in thin air in order to account for massive
quarks, which only live in the UV region. They must come in distinct sets,
representing the chiral global symmetry, with a bifundamental field playing the
role of the chiral condensate. We show that these expectations are born out in
several supersymmetric examples. To analyze most of these properties it is not
necessary to go beyond the probe limit in which one neglects the backreaction
of the flavor D-branes.Comment: 14 pages, LaTeX; references adde
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