93 research outputs found
Classical theta constants vs. lattice theta series, and super string partition functions
Recently, various possible expressions for the vacuum-to-vacuum superstring
amplitudes has been proposed at genus . To compare the different
proposals, here we will present a careful analysis of the comparison between
the two main technical tools adopted to realize the proposals: the classical
theta constants and the lattice theta series. We compute the relevant Fourier
coefficients in order to relate the two spaces. We will prove the equivalence
up to genus 4. In genus five we will show that the solutions are equivalent
modulo the Schottky form and coincide if we impose the vanishing of the
cosmological constant.Comment: 21 page
Benzofuroxan derivatives N-Br and N-I induce intrinsic apoptosis in melanoma cells by regulating AKT/BIM signaling and display anti metastatic activity in vivo
Abstract\ud
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Background\ud
Malignant melanoma is an aggressive type of skin cancer, and despite recent advances in treatment, the survival rate of the metastatic form remains low. Nifuroxazide analogues are drugs based on the substitution of the nitrofuran group by benzofuroxan, in view of the pharmacophore similarity of the nitro group, improving bioavailability, with higher intrinsic activity and less toxicity. Benzofuroxan activity involves the intracellular production of free-radical species. In the present work, we evaluated the antitumor effects of different benzofuroxan derivatives in a murine melanoma model.\ud
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Methods\ud
B16F10-Nex2 melanoma cells were used to investigate the antitumor effects of Benzofuroxan derivatives in vitro and in a syngeneic melanoma model in C57Bl/6 mice. Cytotoxicity, morphological changes and reactive oxygen species (ROS) were assessed by a diphenyltetrasolium reagent, optical and fluorescence microscopy, respectively. Annexin-V binding and mitochondrial integrity were analyzed by flow cytometry. Western blotting and colorimetry identified cell signaling proteins.\ud
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Results\ud
Benzofuroxan N-Br and N-I derivatives were active against murine and human tumor cell lines, exerting significant protection against metastatic melanoma in a syngeneic model. N-Br and N-I induce apoptosis in melanoma cells, evidenced by specific morphological changes, DNA condensation and degradation, and phosphatidylserine translocation in the plasma membrane. The intrinsic mitochondrial pathway in B16F10-Nex2 cells is suggested owing to reduced outer membrane potential in mitochondria, followed by caspase −9, −3 activation and cleavage of PARP. The cytotoxicity of N-Br and N-I in B16F10-Nex2 cells is mediated by the generation of ROS, inhibited by pre-incubation of the cells with N-acetylcysteine (NAC). The induction of ROS by N-Br and N-I resulted in the inhibition of AKT activation, an important molecule related to tumor cell survival, followed by upregulation of BIM.\ud
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Conclusion\ud
We conclude that N-Br and N-I are promising agents aiming at cancer treatment. They may be useful in melanoma therapy as inducers of intrinsic apoptosis and by exerting significant antitumor activity against metastatic melanoma, as presently shown in syngeneic mice.The present work was supported by Fundação de Amparo a Pesquisa do\ud
Estado de São Paulo (FAPESP) and the Conselho Nacional de Desenvolvimento\ud
Científico e Tecnológico (CNPq)
Twelve-crystal prototype of LiMoO scintillating bolometers for CUPID and CROSS experiments
An array of twelve 0.28 kg lithium molybdate (LMO) low-temperature bolometers
equipped with 16 bolometric Ge light detectors, aiming at optimization of
detector structure for CROSS and CUPID double-beta decay experiments, was
constructed and tested in a low-background pulse-tube-based cryostat at the
Canfranc underground laboratory in Spain. Performance of the scintillating
bolometers was studied depending on the size of phonon NTD-Ge sensors glued to
both LMO and Ge absorbers, shape of the Ge light detectors (circular vs.
square, from two suppliers), in different light collection conditions (with and
without reflector, with aluminum coated LMO crystal surface). The scintillating
bolometer array was operated over 8 months in the low-background conditions
that allowed to probe a very low, Bq/kg, level of the LMO crystals
radioactive contamination by Th and Ra.Comment: Prepared for submission to JINST; 23 pages, 9 figures, and 4 table
Perspectives on global leadership and the Covid-19 crisis
As the world struggled to come to grips with the Covid-19 pandemic, over twenty scholars, practitioners, and global leaders wrote brief essays for this curated chapter on the role of global leadership in this extreme example of a global crisis. Their thoughts span helpful theoretical breakthroughs to essential, pragmatic adaptations by companies
A first test of CUPID prototypal light detectors with NTD-Ge sensors in a pulse-tube cryostat
CUPID is a next-generation bolometric experiment aiming at searching for
neutrinoless double-beta decay with ~250 kg of isotopic mass of Mo. It
will operate at 10 mK in a cryostat currently hosting a similar-scale
bolometric array for the CUORE experiment at the Gran Sasso National Laboratory
(Italy). CUPID will be based on large-volume scintillating bolometers
consisting of Mo-enriched LiMoO crystals, facing thin
Ge-wafer-based bolometric light detectors. In the CUPID design, the detector
structure is novel and needs to be validated. In particular, the CUORE cryostat
presents a high level of mechanical vibrations due to the use of pulse tubes
and the effect of vibrations on the detector performance must be investigated.
In this paper we report the first test of the CUPID-design bolometric light
detectors with NTD-Ge sensors in a dilution refrigerator equipped with a pulse
tube in an above-ground lab. Light detectors are characterized in terms of
sensitivity, energy resolution, pulse time constants, and noise power spectrum.
Despite the challenging noisy environment due to pulse-tube-induced vibrations,
we demonstrate that all the four tested light detectors comply with the CUPID
goal in terms of intrinsic energy resolution of 100 eV RMS baseline noise.
Indeed, we have measured 70--90 eV RMS for the four devices, which show an
excellent reproducibility. We have also obtained outstanding energy resolutions
at the 356 keV line from a Ba source with one light detector achieving
0.71(5) keV FWHM, which is -- to our knowledge -- the best ever obtained when
compared to detectors of any technology in this energy range.Comment: Prepared for submission to JINST; 16 pages, 7 figures, and 1 tabl
Dark Matter detection with the COSINUS experiment
Using a NaI target is essential to test the long-standing
DAMA/LIBRA claim of the detection of a Dark Matter (DM) signal in a model independent way. COSINUS is developing the first cryogenic scintillating calorimeter based on a NaI absorber. This technique provides an event-by-event particle
identification strategy based on a dual-channel readout (heat and light). An excellent energy resolution and a low threshold are essential for a direct detection DMexperiment. In this regard, Transition Edge Sensors (TESs) are an established technology that has already proven its potential in other leading cryogenic DM experiments (like CRESST-III). However, the hygroscopicity of NaI prevents the deposition of the TES sensor directly onto its surface, which would guarantee optimal thermal coupling. For this reason, COSINUS adopted an alternative design for the heat channel readout, called remoTES, which is currently in the R&D phase and has already shown promising results (in terms of energy threshold and resolution) when tested on various absorbers (Si, TeO2)
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