284 research outputs found
The vibration based diagnostics of ship propulsion systems
The article has been worked out on the basis of the report devoted to the
conducted diagnostic investigations of the ship main propulsion unitās mechanical system.
Gdansk University of Technology has been ordered with such investigations by the repair
Shipyard carrying out the shipās overhaul. Diagnostic tests involved measurements and
analyses of the vibration signals generated in selected constructional kinematic pairs of the
identical (twin) starboard and portside marine propulsion lines. The vibration signals have
been registered at the representative load ranges. By this way the stability of the considered
mechanical unit has been estimated both in a global and local sense. Appearing at that time the
resonance phenomena which result in a kinetic energy dissipation of the ship main
propulsion unitās masses being in a rotational movement have been identified. There
have been also localized places of the largest growth of the changeable internal
tensionsā amplitudes, what considerably constrains cycles number of the load alterations
at which elements transmitting the propulsion torque from engines to propellers crack, as a result
of the material fatigue phenomenon.
The most probable reasons of the mechanical unitās enlarged vibration level have been pointed out
on the basis of a carried out analysis of the alignment results, the specifity of the applied main
engine running on the partial loads as well as the range of constructional changes
that had been made during the propulsion unitās overhaul. Results of the repeated
diagnostic sea trials, carried out after the reduction gearsā modification recommended by the
Authors, confirmed a relevance of the earlier formulated diagnosis. The modification works aimed
to perform a resonance offset by the damping correction of hydraulic devices
additionally founded on the gears frames.
A technology of the marine propulsion shaft lineās transverse and longitudinal vibration
measurements carried out by means of the portable vibration register as well as a method of the
vibration spectral analysis have been focused within the program description of the
performed diagnostic investigations. They represented the base for a diagnostic
inference
about the considered mechanical unitās dynamic state
The importance of preoperative elevated serum levels of CEA and CA15-3 in patients with breast cancer in predicting its histological type.
It is not known whether in patients with breast cancer the occurrence of elevated serum tumour markers depends on its histological type. The aim of the study was to assess relationship between breast cancer histological type and the presence of increased serum levels of CEA and CA 15-3. The study population was 428 patients (all women, mean age 52.5 years), treated at The Department of Surgery of Wroclaw Medical University from 2005 to 2008 due to breast cancer. All of them had their preoperative CA 15-3 and CEA serum concentrations measured. According to the TNM system, 21% of patients were in stage I, 32.5% in stage II, 46.5% in stage III of the disease. In patients with ductal type of the cancer the elevated serum levels of CEA and CA 15-3 were observed in 48.7% and 42.2%, in lobular type in 42.4% and 52.5%, and in non-ductal/tubular types in 48.1% and 40.4% (p=N/S). Stepwise logistic regression analyses showed that ductal breast cancer is related to elevated CEA and normal CA 15-3 serum levels. The histological types of breast cancer are not significantly related to elevated serum levels of CEA and/or CA 15-3
Prognostic value of CA 19-9 level in resectable pancreatic adenocarcinoma.
The prognosis in patients with pancreatic cancer is poor and some authors describe it as a lethal disease. At the time of diagnosis only 14% of patients could be surgically treated and up to 30% of them die within 12 months. Therefore, further clinical investigations on preoperative patient qualification are needed. A total of 81 patients were included into the study. The CA 19-9 concentration was measured before surgery by an automated, commercially available enzyme immunoassay in Axsym analyzer (Abott Diagnostics Laboratory). A value of 37 U/ml was used as the upper limit of normal levels. Tumors were staged according to the Union Against Cancer (UICC) of 2004 and graded during the histological evaluation according to the G0-G4 scale. All patients were monitored every three month via outpatient clinic visits. In the case of missing visit we contacted the families to establish the cause. We assessed perioperative, 12 month, 2 year and 5 year survival. Twelve moth, 2 year and 5 year survival were assessed in the whole studied population and in the group of patients with the exception of these who died during the perioperative period. The total five year survival was 6%. The median time of survival was 467 days (range: 163 - 586 days). The perioperative period was survived by 91.4% patients, 12 months were survived by 71.6% patients, 2 years were survived by 35.8% patients, 5 years were survived by 6.2% patients. The serum Ca 19-9 level was above the normal limit in 80.5% patients. ROC curve analysis revealed that CA 19-9 level of more than 106 U/ml was linked to 2 year survival with 79.3% sensitivity and 74.5% specificity. Preoperative level of CA 19-9 below 106U/ml represents a predictive factor of 2- and 5-year survival, independent of other factors, such as lower size of the tumor, absence of metastases to lymph nodes, female gender of patients. After exclusion of the patients who died in the perioperative period, no relationship could have been disclosed between preoperative CA 19-9 levels and one year survival. The observation points to the chance that patients with higher levels of CA 19-9 harbour micrometastases, the development of which is sufficiently slow to allow for a one-year survival of the patients but which increase the risk of death after two and five years
SMYD1, the myogenic activator, is a direct target of serum response factor and myogenin
SMYD1 is a heart and muscle specific SET-MYND domain containing protein, which functions as a histone methyltransferase and regulates downstream gene transcription. We demonstrated that the expression of SMYD1 is restricted in the heart and skeletal muscle tissues in human. To reveal the regulatory mechanisms of SMYD1 expression during myogenesis and cardiogenesis, we cloned and characterized the human SMYD1 promoter, which contains highly conserved serum response factor (SRF) and myogenin binding sites. Overexpression of SRF and myogenin significantly increased the endogenous expression level of Smyd1 in C2C12 cells, respectively. Deletion of Srf in the heart of mouse embryos dramatically decreased the expression level of Smyd1 mRNA and the expression of Smyd1 can be rescued by exogenous SRF introduction in SRF null ES cells during differentiation. Furthermore, we demonstrated that SRF binds to the CArG site and myogenin binds to the E-box element on Smyd1 promoter region using EMSA and ChIP assays. Moreover, forced expression of SMYD1 accelerates myoblast differentiation and myotube formation in C2C12 cells. Taken together, these studies demonstrated that SMYD1 is a key regulator of myogenic differentiation and acts as a downstream target of muscle regulatory factors, SRF and myogenin
Fracture of disordered solids in compression as a critical phenomenon: I. Statistical mechanics formalism
This is the first of a series of three articles that treats fracture
localization as a critical phenomenon. This first article establishes a
statistical mechanics based on ensemble averages when fluctuations through time
play no role in defining the ensemble. Ensembles are obtained by dividing a
huge rock sample into many mesoscopic volumes. Because rocks are a disordered
collection of grains in cohesive contact, we expect that once shear strain is
applied and cracks begin to arrive in the system, the mesoscopic volumes will
have a wide distribution of different crack states. These mesoscopic volumes
are the members of our ensembles. We determine the probability of observing a
mesoscopic volume to be in a given crack state by maximizing Shannon's measure
of the emergent crack disorder subject to constraints coming from the
energy-balance of brittle fracture. The laws of thermodynamics, the partition
function, and the quantification of temperature are obtained for such cracking
systems.Comment: 11 pages, 2 figure
Rupture by damage accumulation in rocks
The deformation of rocks is associated with microcracks nucleation and
propagation, i.e. damage. The accumulation of damage and its spatial
localization lead to the creation of a macroscale discontinuity, so-called
"fault" in geological terms, and to the failure of the material, i.e. a
dramatic decrease of the mechanical properties as strength and modulus. The
damage process can be studied both statically by direct observation of thin
sections and dynamically by recording acoustic waves emitted by crack
propagation (acoustic emission). Here we first review such observations
concerning geological objects over scales ranging from the laboratory sample
scale (dm) to seismically active faults (km), including cliffs and rock masses
(Dm, hm). These observations reveal complex patterns in both space (fractal
properties of damage structures as roughness and gouge), time (clustering,
particular trends when the failure approaches) and energy domains (power-law
distributions of energy release bursts). We use a numerical model based on
progressive damage within an elastic interaction framework which allows us to
simulate these observations. This study shows that the failure in rocks can be
the result of damage accumulation
Measuring our universe from galaxy redshift surveys
Galaxy redshift surveys have achieved significant progress over the last
couple of decades. Those surveys tell us in the most straightforward way what
our local universe looks like. While the galaxy distribution traces the bright
side of the universe, detailed quantitative analyses of the data have even
revealed the dark side of the universe dominated by non-baryonic dark matter as
well as more mysterious dark energy (or Einstein's cosmological constant). We
describe several methodologies of using galaxy redshift surveys as cosmological
probes, and then summarize the recent results from the existing surveys.
Finally we present our views on the future of redshift surveys in the era of
Precision Cosmology.Comment: 82 pages, 31 figures, invited review article published in Living
Reviews in Relativity, http://www.livingreviews.org/lrr-2004-
Report and preliminary results of SONNE Cruise SO 145/2 [SO145/2], Talcahuano (Chile) - Arica (Chile), February 4 - February 29, 2000
Mathematical Model of Stem Cell Differentiation and Tissue Regeneration with Stochastic Noise
- ā¦