1,229 research outputs found
Phantom scalar-tensor models and cosmological tensions
We study three different extended scalar-tensor theories of gravity by also
allowing a negative sign for the kinetic term for the scalar field in the
Jordan frame. Our scope is to understand how the observational constraints for
these models cope with the volume of the parameter space in which the theory is
healthy. Models with a negative kinetic term lead to decreasing effective
gravitational constant with redshift and behave as an effective relativistic
component with a negative energy density as opposite to their corresponding
version with a standard kinetic term. As a consequence, we find that the
extended branch with a negative sign for the kinetic term correspond in general
to lower and compared to CDM. We find that in all the
cases with a negative sign for the kinetic term studied here, cosmological
observations constrain these models around GR and prefer a volume of the
parameter space in which the theory is not healthy since the scalar field
behave as a ghost also in the related Einstein frame. We show that also in the
phantom branch early modify gravity with a quartic coupling can substantially
reduce the tension fitting the combination of cosmic microwave background
data from Planck, baryon acoustic oscillations from BOSS and eBOSS, and
Supernovae from the Pantheon sample with calibration information by SH0ES.Comment: 33 pages, 11 figures, 6 table
Cosmological effects of the Galileon term in Scalar-Tensor Theories
We study the cosmological effects of a Galileon term in scalar-tensor
theories of gravity. The subset of scalar-tensor theories considered are
characterized by a non-minimal coupling , a kinetic term with
arbitrary sign with , a potential
, and a Galileon term . In addition to the modified dynamics, the Galileon term provides a
screening mechanism to potentially reconcile the models with General Relativity
predictions inside a Vainshtein radius. Thanks to the Galileon term, the
stability conditions, namely ghost and Laplacian instabilities, in the branch
with a negative kinetic term () are fulfilled for a large volume of the
parameter space. Solving numerically the background evolution and linear
perturbations, we derive the constraints on the cosmological parameters in
presence of a Galileon term for different combination of the cosmic microwave
background (CMB) data from Planck, baryon acoustic oscillations (BAO)
measurements from BOSS, and supernovae from the Pantheon compilation. We find
that the Galileon term alters the dynamics of all the studied cases. For a
standard kinetic term (), we find that Planck data and a compilation of
BAO data constrain the Galileon term to small values that allow screening very
inefficiently. For a negative kinetic term (), a Galileon term and a
non-zero potential lead to an efficient screening in a physically viable regime
of the theory, with a value for the Hubble constant today which alleviates the
tension between its CMB and local determinations. For a vanishing potential,
the case with and the Galileon term driving the late acceleration of the
Universe is ruled out by Planck data.Comment: 23 pages, 15 figures, 4 table
An effective 6DoF motion model for 3D-6DoF Monte Carlo Localization
This paper deals with the probabilistic 6DoF motion model of a wheeled road vehicle. It allows to correctly model the error introduced by dead reckoning. Furthermore, to stress the importance of an appropriate motion model, i.e., that different models are not equally good, we show that another model, which was previously developed, does not allow a correct representation of the uncertainty, therefore misguiding 3D-6DoF Monte Carlo Localization. We also present some field experiments to demonstrate that our model allow a consistent determination of the 6DoF vehicle pose
Improved overall survival in dendritic cell vaccination-induced immunoreactive subgroup of advanced melanoma patients
BACKGROUND: We present our experience of therapeutic vaccination using dendritic cells (DC) pulsed with autologous tumor antigens in patients with advanced melanoma. METHODS: Twenty-one pretreated advanced melanoma patients were vaccinated with autologous DC pulsed with 100 μg/ml of autologous-tumor-lysate (ATL) or – homogenate (ATH) and 50 μg/ml of keyhole limpet hemocyanin (KLH). The first 8 patients were treated subcutaneously or intradermally with immature-DC (iDC) (range 4.5 – 82 × 10(6)) and the remaining 13 intradermally with in vitro matured DC (mDC) (range 1.2–26 × 10(6)). Subcutaneous interleukin-2 (3 × 10(6 )IU) was administered from days 3 to 7 of each treatment cycle. RESULTS: Three of the 8 iDC patients obtained stabilizations (SD), each of 6 months' duration. The 13 mDC patients showed 1 complete response (8 months), 1 partial response (3 months), 2 mixed responses (6 and 12 months) and 3 SD (9, 7+, and 3+ months). Overall responses (OR) were observed in 4/21 (19%) patients, or 4/13 (30.7%) considering mDC treatment only. 10/21 (47.6%) patients showed non progressive disease (NPD), with 7/13 (53.8%) cases of NPD for mDC-treated patients. No major toxicities were observed. The positive delayed-type hypersensitivity (DTH) test to ATL/ATH and/or KLH correlated with increased overall survival (OS). Median OS was 24 months (range 3 – 45) for the 10 DTH-positive (1 iDC and 9 mDC) and 5 months (range 3–14) for the 11 DTH-negative patients (P < 0.001). The in vitro evaluation of gamma IFN-secreting T-cells in 10 patients showed good correlation with both DTH (75%) and clinical outcome (70%). CONCLUSION: Vaccination using DC pulsed with ATL/ATH and KLH in advanced melanoma patients is well tolerated and can induce a clinical response, especially when mDC are used. Successful immunization, verified by positive DTH, leads to longer survival
Second-line high-dose chemotherapy in patients with mediastinal and retroperitoneal primary non-seminomatous germ cell tumors: the EBMT experience
Background: Results of second-line chemotherapy in patients with extragonadal non-seminomatous germ cell tumor (NSGCT) appear inferior to results in testicular NSGCT. Patients with retroperitoneal NSGCT achieve a comparable long-term survival rate of 30%, but the salvage rates of patients with mediastinal primary are less than 10%. We conducted a retrospective analysis on patients with mediastinal and retroperitoneal NSGCT treated with second-line high-dose chemotherapy (HDCT) registered with the European Group for Blood and Marrow Transplantation (EBMT). Patients and methods: Between 1987 and 1999, 59 registered patients with retroperitoneal (n=37) and mediastinal (n=22) primary NSGCT, median age 28 years (range 18-60), were treated with second-line HDCT. All had received cisplatin-containing chemotherapy as first-line treatment. Results: Toxic death occurred in three cases (5%). With a median follow-up of 58 months (range 14-114), 18/59 patients (30%) continue to be disease-free. Of three patients who had a disease recurrence after HDCT, one patient achieved a disease-free status with further chemotherapy and surgery. In total, 19 patients (32%) are currently disease-free. Sixteen of 37 patients (43%) with retroperitoneal NSGCT, and three of 22 patients (14%) with mediastinal NSGCT are currently alive and disease-free. Conclusions: Second-line HDCT might represent a possible option for patients with retroperitoneal primary NSGCT. New salvage strategies are needed for patients with mediastinal NSGC
Effect of raloxifene on IGF-I and IGFBP-3 in postmenopausal women with breast cancer
The effect on the IGF system of 60 mg and 600 mg daily of raloxifene administered for 2 weeks prior to surgery was investigated in 37 postmenopausal women with breast cancer. Raloxifene significantly decreased insulin-like growth factor (IGF-I) as compared to placebo (P < 0.05) with no dose–response relationship. No significant change was observed in IGFBP-3, while the IGF-I/IGFBP-3 molar ratio was decreased by treatment, with a statistically significant effect only for the higher dose. Given that high plasma levels of IGF-I have been suggested as a risk factor for breast cancer, these findings provide further support for the potential activity of raloxifene in breast cancer prevention. © 2001 Cancer Research Campaign http://www.bjcancer.co
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