304 research outputs found
Planck LFI flight model feed horns
this paper is part of the Prelaunch status LFI papers published on JINST:
http://www.iop.org/EJ/journal/-page=extra.proc5/jinst The Low Frequency
Instrument is optically interfaced with the ESA Planck telescope through 11
corrugated feed horns each connected to the Radiometer Chain Assembly (RCA).
This paper describes the design, the manufacturing and the testing of the
flight model feed horns. They have been designed to optimize the LFI optical
interfaces taking into account the tight mechanical requirements imposed by the
Planck focal plane layout. All the eleven units have been successfully tested
and integrated with the Ortho Mode transducers.Comment: This is an author-created, un-copyedited version of an article
accepted for publication in JINST. IOP Publishing Ltd is not responsible for
any errors or omissions in this version of the manuscript or any version
derived from it. The definitive publisher authenticated version is available
online at 10.1088/1748-0221/4/12/T1200
The Planck-LFI flight model composite waveguides
The Low Frequency Instrument on board the PLANCK satellite is designed to
give the most accurate map ever of the CMB anisotropy of the whole sky over a
broad frequency band spanning 27 to 77 GHz. It is made of an array of 22
pseudo-correlation radiometers, composed of 11 actively cooled (20 K) Front End
Modules (FEMs), and 11 Back End Modules (BEMs) at 300K. The connection between
the two parts is made with rectangular Wave Guides. Considerations of different
nature (thermal, electromagnetic and mechanical), imposed stringent
requirements on the WGs characteristics and drove their design. From the
thermal point of view, the WG should guarantee good insulation between the FEM
and the BEM sections to avoid overloading the cryocooler. On the other hand it
is essential that the signals do not undergo excessive attenuation through the
WG. Finally, given the different positions of the FEM modules behind the focal
surface and the mechanical constraints given by the surrounding structures,
different mechanical designs were necessary. A composite configuration of
Stainless Steel and Copper was selected to satisfy all the requirements. Given
the complex shape and the considerable length (about 1.5-2 m), manufacturing
and testing the WGs was a challenge. This work deals with the development of
the LFI WGs, including the choice of the final configuration and of the
fabrication process. It also describes the testing procedure adopted to fully
characterize these components from the electromagnetic point of view and the
space qualification process they underwent. Results obtained during the test
campaign are reported and compared with the stringent requirements. The
performance of the LFI WGs is in line with requirements, and the WGs were
successfully space qualified.Comment: this paper is part of the Prelaunch status LFI papers published on
JINST: http://www.iop.org/EJ/journal/-page=extra.proc5/jins
Split crest technique for implant treatment of agenesis of the upper lateral incisors: results of a randomized pilot histological and clinical study at 24-month follow-up
Agenesis of lateral incisors, besides the functional issues, represents a great esthetic drawback. The selection of an appropriate treatment is a complex decision, which should consider the stability of the clinical outcomes over time. The aim of the present study was a histological and clinical comparison of two-stage split crest technique (SCT), with bone chips alone or mixed with porcine bone in patients affected by unilateral and bilateral agenesis of the upper lateral incisors. Eleven patients were enrolled, and randomly assigned to receive a treatment with autologous bone chips (group 1) or autologous bone chips mixed 1:1 to porcine-derived xenogenic bone (group 2). After a 2-month healing period, implants were placed and biopsies harvested for histomorphometrical evaluation. Clinical assessment, according to ICOI PISA health scale, and radiographic marginal bone loss evaluation at 12- and 24-month follow-ups were conducted. The histomorphometry showed significantly greater new bone formation (p > 0.0229) in group 2. At 12- and 24-month follow-ups, all the evaluated implants, regardless of the group they were allocated, could be categorized as "success" in the ICOI Pisa Health Scale for Dental Implants, and did not show significant difference in crestal bone loss. To the best of our knowledge, these are the first histological and clinical outcomes indicating that the use of bone chips mixed 1:1 to porcine bone in SCT could be a promising technique for the rehabilitation of patients with agenesis of the upper lateral incisors, although studies with a larger number of patients and implants, and a longer follow up are needed
Planck-LFI radiometers' spectral response
The Low Frequency Instrument (LFI) is an array of pseudo-correlation
radiometers on board the Planck satellite, the ESA mission dedicated to
precision measurements of the Cosmic Microwave Background. The LFI covers three
bands centred at 30, 44 and 70 GHz, with a goal bandwidth of 20% of the central
frequency.
The characterization of the broadband frequency response of each radiometer
is necessary to understand and correct for systematic effects, particularly
those related to foreground residuals and polarization measurements. In this
paper we present the measured band shape of all the LFI channels and discuss
the methods adopted for their estimation. The spectral characterization of each
radiometer was obtained by combining the measured spectral response of
individual units through a dedicated RF model of the LFI receiver scheme.
As a consistency check, we also attempted end-to-end spectral measurements of
the integrated radiometer chain in a cryogenic chamber. However, due to
systematic effects in the measurement setup, only qualitative results were
obtained from these tests. The measured LFI bandpasses exhibit a moderate level
of ripple, compatible with the instrument scientific requirements.Comment: 16 pages, 9 figures, this paper is part of the Prelaunch status LFI
papers published on JINST:
http://www.iop.org/EJ/journal/-page=extra.proc5/jins
Nicotinamide inhibits melanoma in vitro and in vivo
Background: Even though new therapies are available against melanoma, novel approaches are needed to overcome resistance and high-toxicity issues. In the present study the anti-melanoma activity of Nicotinamide (NAM), the amide form of Niacin, was assessed in vitro and in vivo. Methods: Human (A375, SK-MEL-28) and mouse (B16-F10) melanoma cell lines were used for in vitro investigations. Viability, cell-death, cell-cycle distribution, apoptosis, Nicotinamide Adenine Dinucleotide+ (NAD+), Adenosine Triphosphate (ATP), and Reactive Oxygen Species (ROS) levels were measured after NAM treatment. NAM anti-SIRT2 activity was tested in vitro; SIRT2 expression level was investigated by in silico transcriptomic analyses. Melanoma growth in vivo was measured in thirty-five C57BL/6 mice injected subcutaneously with B16-F10 melanoma cells and treated intraperitoneally with NAM. Interferon (IFN)-γ-secreting murine cells were counted with ELISPOT assay. Cytokine/chemokine plasmatic levels were measured by xMAP technology. Niacin receptors expression in human melanoma samples was also investigated by in silico transcriptomic analyses. Results: NAM reduced up to 90% melanoma cell number and induced: I) accumulation in G1-phase (40% increase), ii) reduction in S- A nd G2-phase (about 50% decrease), iii) a 10-fold increase of cell-death and 2.5-fold increase of apoptosis in sub-G1 phase, iv) a significant increase of NAD+, ATP, and ROS levels, v) a strong inhibition of SIRT2 activity in vitro. NAM significantly delayed tumor growth in vivo (p ≤ 0.0005) and improved survival of melanoma-bearing mice (p ≤ 0.0001). About 3-fold increase (p ≤ 0.05) of Interferon-gamma (IFN-γ) producing cells was observed in NAM treated mice. The plasmatic expression levels of 6 cytokines (namely: Interleukin 5 (IL-5), Eotaxin, Interleukin 12 (p40) (IL12(p40)), Interleukin 3 (IL-3), Interleukin 10 (IL-10) and Regulated on Activation Normal T Expressed and Secreted (RANTES) were significantly changed in the blood of NAM treated mice, suggesting a key role of the immune response. The observed inhibitory effect of NAM on SIRT2 enzymatic activity confirmed previous evidence; we show here that SIRT2 expression is significantly increased in melanoma and inversely related to melanoma-patients survival. Finally, we show for the first time that the expression levels of Niacin receptors HCAR2 and HCAR3 is almost abolished in human melanoma samples. Conclusion: NAM shows a relevant anti-melanoma activity in vitro and in vivo and is a suitable candidate for further clinical investigations
High Performances Corrugated Feed Horns for Space Applications at Millimetre Wavelengths
We report on the design, fabrication and testing of a set of high performance
corrugated feed horns at 30 GHz, 70 GHz and 100 GHz, built as advanced
prototypes for the Low Frequency Instrument (LFI) of the ESA Planck mission.
The electromagnetic designs include linear (100 GHz) and dual shaped (30 and 70
GHz) profiles. Fabrication has been achieved by direct machining at 30 GHz, and
by electro-formation at higher frequencies. The measured performances on side
lobes and return loss meet the stringent Planck requirements over the large
(20%) instrument bandwidth. Moreover, the advantage in terms of main lobe shape
and side lobes levels of the dual profiled designs has been demonstrated.Comment: 16 pages, 7 figures, accepted for publication in Experimental
Astronom
Dental pulp stem cells bioadhesivity: evaluation on mineral-trioxide-aggregate.
Stem cells are undifferentiated cells that have the capacity to self-renew. They have been discovered in many adult tissues, including teeth. Dental Pulp Mesenchymal Stem Cells (DP-MSCs) are involved in dental repair by activation of growth factors, released after caries and have the ability to regenerate a dentin-pulp-like complex. The molecular/cellular research gives the possibility to grow new tissues and biological structures for clinical applications, providing cells for therapies including cell transplantation and tissue engineering. In this study DP-MSCs were derived from dental pulp of 10 donors. To evaluate material toxicity, after in vitro isolation, the cells were seeded on mineral trioxide aggregate (MTA). Initial light microscopy investigation of cells revealed no signs of cell death due to toxicity or infection, on the contrary the scaffolds supplied an excellent support for cell structures, the cells proliferated and adhered to substrate. Similar observation was seen in scanning electron microscopy, in particular the cells had proliferated and spread, covering a considerable part of the surface of the biomaterials investigated, with an elaborate form of attachment, in fact, the cells formed a continuous layer on the upper surface of the MTA. In conclusion, the aim of this study is to demonstrate that DP-MSCs combined with MTA could be a potential source for regenerative medicine, encouraging further study to evaluate the new-dentin formation
The linearity response of the Planck-LFI flight model receivers
In this paper we discuss the linearity response of the Planck-LFI receivers,
with particular reference to signal compression measured on the 30 and 44 GHz
channels. In the article we discuss the various sources of compression and
present a model that accurately describes data measured during tests performed
with individual radiomeric chains. After discussing test results we present the
best parameter set representing the receiver response and discuss the impact of
non linearity on in-flight calibration, which is shown to be negligible.Comment: this paper is part of the Prelaunch status LFI papers published on
JINST: http://www.iop.org/EJ/journal/-page=extra.proc5/jinst; This is an
author-created, un-copyedited version of an article accepted for publication
in JINST. IOP Publishing Ltd is not responsible for any errors or omissions
in this version of the manuscript or any version derived from it. The
definitive publisher authenticated version is available online at
10.1088/1748-0221/4/12/T12011
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