27 research outputs found
Test of mode coupling theory for a supercooled liquid of diatomic molecules. II. q-dependent orientational correlators
Using molecular dynamics computer simulations we study the dynamics of a
molecular liquid by means of a general class of time-dependent correlators
S_{ll'}^m(q,t) which explicitly involve translational (TDOF) and orientational
degrees of freedom (ODOF). The system is composed of rigid, linear molecules
with Lennard- Jones interactions. The q-dependence of the static correlators
S_{ll'}^m(q) strongly depend on l, l' and m. The time dependent correlators are
calculated for l=l'. A thorough test of the predictions of mode coupling theory
(MCT) is performed for S_{ll}^m(q,t) and its self part S_{ll}^{(s)m}(q,t), for
l=1,..,6. We find a clear signature for the existence of a single temperature
T_c, at which the dynamics changes significantly. The first scaling law of MCT,
which involves the critical correlator G(t), holds for l>=2, but no critical
law is observed. Since this is true for the same exponent parameter lambda as
obtained for the TDOF, we obtain a consistent description of both, the TDOF and
ODOF, with the exception of l=1. This different behavior for l \ne 1 and l=1
can also be seen from the corresponding susceptibilities
(chi'')_{ll}^m(q,omega) which exhibit a minimum at about the same frequency
omega_{min} for all q and all l \ne 1, in contrast to (chi'')_{11}^m(q,omega)
for which omega'_{min} approx 10 omega_{min} . The asymptotic regime, for which
the first scaling law holds, shrinks with increasing l. The second scaling law
of MCT (time-temperature superposition principle) is reasonably fulfilled for l
\ne 1 but not for l=1. Furthermore we show that the q- and (l,m)-dependence of
the self part approximately factorizes, i.e. S_{ll}^{(s)m}(q,t) \cong
C_l^{(s)}(t) F_s(q,t) for all m.Comment: 11 pages of RevTex, 16 figure
Expression of CD56 isoforms in primary and relapsed adult granulosa cell tumors of the ovary
<p>Abstract</p> <p>Background</p> <p>Adult granulosa cell tumors of the ovary (GCTs) are sex cord stromal tumors of unpredictable behaviour. Up to now, the prediction of the relapsing/malignant potential remains difficult. CD56 (NCAM) in GCTs was previously described in only two studies. However, the expression of its isoforms was not examined.</p> <p>Methods</p> <p>30 GCTs (16 primaries, 14 relapses) were investigated immunohistochemically with antibodies against Pan-CD56 (CD56<sup>Pan</sup>) and the isoform with 140/180 kDa length (CD56<sup>140/180 kDa</sup>). The reaction was assessed with respect to percentage of positive cells and intensity of staining.</p> <p>Results</p> <p>In all GCTs, CD56<sup>Pan </sup>was expressed, but differences were found between primaries and relapses. The percentage of CD56<sup>Pan </sup>positive tumor cells was lower in relapses, whereas CD56<sup>140/180 kDa </sup>showed a higher staining intensity in the latter.</p> <p>Conclusion</p> <p>Expression of CD56 is an additional sensitive and helpful immunohistochemical tool for histopathologists diagnosing a GCT. It does not seem possible to provide a validly individual risk assessement. However, the different expression of CD56 isoforms might indicate important changes in the course to a more malignant behaviour.</p
Test of mode coupling theory for a supercooled liquid of diatomic molecules.I. Translational degrees of freedom
A molecular dynamics simulation is performed for a supercooled liquid of
rigid diatomic molecules. The time-dependent self and collective density
correlators of the molecular centers of mass are determined and compared with
the predictions of the ideal mode coupling theory (MCT) for simple liquids.
This is done in real as well as in momentum space. One of the main results is
the existence of a unique transition temperature T_c, where the dynamics
crosses over from an ergodic to a quasi-nonergodic behavior. The value for T_c
agrees with that found earlier for the orientational dynamics within the error
bars. In the beta- regime of MCT the factorization of space- and time
dependence is satisfactorily fulfilled for both types of correlations. The
first scaling law of ideal MCT holds in the von Schweidler regime, only, since
the validity of the critical law can not be confirmed, due to a strong
interference with the microscopic dynamics. In this first scaling regime a
consistent description within ideal MCT emerges only, if the next order
correction to the asymptotic law is taken into account. This correction is
almost negligible for q=q_max, the position of the main peak in the static
structure factor S(q), but becomes important for q=q_min, the position of its
first minimum. The second scaling law, i.e. the time-temperature superposition
principle, holds reasonably well for the self and collective density
correlators and different values for q. The alpha-relaxation times tau_q^(s)
and tau_q follow a power law in T-T_c over 2 -- 3 decades. The corresponding
exponent gamma is weakly q-dependent and is around 2.55. This value is in
agreement with the one predicted by MCT from the value of the von Schweidler
exponent but at variance with the corresponding exponent gammaComment: 14 pages of RevTex, 19 figure
The Effect of Optical Conditioning of Preparations with Scan Spray on Preparation Form
Svrha rada: Za primjenu sustava CAD/CAM u ordinacijama dentalne medicine potrebno je odabrati sprej za skeniranje. Njegovom primjenom mijenja se prekrivena preparacija, što može nepovoljno
utjecati na rubno zatvaranje i interno prianjanje restauracije. Zadaća ovog istraživanja bila je odrediti utjecaj spreja na preparacijsku formu procjenom morfologije i debljine triju različitih sprejeva za skeniranje. Materijali i metode: Određivala se površinska morfologija prekrivanja triju (A, B, C) različitih sprejeva za skeniranje uz pomoć konfokalnoga laserskog mikroskopa. Debljina sprejem nanesenog premaza mjerila se na staklenoj pločici i u simuliranim kliničkim uvjetima profilometrom i uređajem za digitalizaciju površine. Podaci su analizirani jednosmjernim testom ANOVA (α = .05). Rezultati: Konfokalni laserski mikroskop prikazao je grubu i nepravilnu sprejem
pokrivenu površinu nakon uporabe svih sprejeva, te se od spreja A preko spreja B do spreja C broj malih zrnaca povećavao. Srednja debljina prekrivanja na staklenoj pločici iznosila je za sprej A 25,3 Μm, za B 18,9 Μm i za C 19,2 Μm. Statistički značajne razlike bile su između sprejeva A i B (p=0,017). U simuliranim kliničkim uvjetima srednja debljina prekrivanja iznosila je za sprej A 15,5 Μm, za B 15,0 Μm i za C 13,3 Μm. Razlika je bila statistički značajna samo između
sprejeva A i C (p=0,033). Zaključak: Premazi nakon korištenja različitih sprejeva imali su drugačije površinske morfologije i različite debljine. Posljedično tome primjena spreja za skeniranje utječe i na konačnu CAD/CAM restauraciju, premda se kliničkim korištenjem postigla prihvatljiva debljina prekrivanja.Objective: CAD/CAM systems require scan spray for chairside sampling of tooth surfaces. However, this leads to alterations of the sprayed preparation and may affect marginal and internal adaption
of the restoration. The aim of this study was to define the effect of scan spray on preparation form by evaluating the morphologies and the thicknesses of three different scan sprays. Materials and Methods: The surface morphology of the coatings of different scan sprays (A, B, C) was evaluated by use of a confocal laser scanning microscope. The thicknesses of spray coatings were measured on a glass plate as well as under simulated clinical conditions using a profilometer and a surface digitalisation device. The data were analysed by a 1-way ANOVA (α = .05). Results: The confocal laser scanning microscopy showed rough and irregular formed coating surfaces of all sprays, whereas an increasing numbers of small spray particles were seen from spray A over spray B to spray C. Mean coating thicknesses on the glass plate were: spray A 25.3 Μm, spray B 18.9 Μm and spray C 19.2 Μm. Significant differences were detected between spray A and B (P = .017). Under simulated clinical conditions median coating thicknesses were: spray A 15.5 Μm, spray B 15.0 Μm and spray C 13.3 Μm. A statistically significant difference could be detected only between spray A and C (P = .033). Conclusions: The coatings of the used scan spray systems showed different surface morphologies and exhibited different thicknesses. Consequently, the application of scan sprays affects the precision of the final CAD/CAM restorations. However, the scan sprays under investigation showed acceptable coating thicknesses for clinical use
Dynamics of the rotational degrees of freedom in a supercooled liquid of diatomic molecules
Using molecular dynamics computer simulations, we investigate the dynamics of
the rotational degrees of freedom in a supercooled system composed of rigid,
diatomic molecules. The interaction between the molecules is given by the sum
of interaction-site potentials of the Lennard-Jones type. In agreement with
mode-coupling theory (MCT), we find that the relaxation times of the
orientational time correlation functions C_1^(s), C_2^(s) and C_1 show at low
temperatures a power-law with the same critical temperature T_c, and which is
also identical to the critical temperature for the translational degrees of
freedom. In contrast to MCT we find, however, that for these correlators the
time-temperature superposition principle does not hold well and that also the
critical exponent gamma depends on the correlator. We also study the
temperature dependence of the rotational diffusion constant D_r and demonstrate
that at high temperatures D_r is proportional to the translational diffusion
constant D and that when the system starts to become supercooled the former
shows an Arrhenius behavior whereas the latter exhibits a power-law dependence.
We discuss the origin for the difference in the temperature dependence of D (or
the relaxation times of C_l^(s) and D_r. Finally we present results which show
that at low temperatures 180 degree flips of the molecule are an important
component of the relaxation dynamics for the orientational degrees of freedom.Comment: 17 pages of RevTex, 12 figure
Adjuvant Radiotherapy in Patients with Squamous Cell Carcinoma of the Oral Cavity or Oropharynx and Solitary Ipsilateral Lymph Node Metastasis (pN1) : A Prospective Multicentric Cohort Study
(1) Background: Evaluation of impact of adjuvant radiation therapy (RT) in patients with
oral squamous cell carcinoma of the oral cavity/oropharynx (OSCC) of up to 4 cm (pT1/pT2) and
solitary ipsilateral lymph node metastasis (pN1). A non-irradiated group with clinical follow-up was
chosen for control, and survival and quality of life (QL) were compared; (2) Methods: This prospective
multicentric comprehensive cohort study included patients with resected OSCC (pT1/pT2, pN1,
and cM0) who were allocated into adjuvant radiation therapy (RT) or observation. The primary
endpoint was overall survival. Secondary endpoints were progression-free survival and QL after
surgery; (3) Results: Out of 27 centers, 209 patients were enrolled with a median follow-up of 3.4 years.
An amount of 137 patients were in the observation arm, and 72 received adjuvant irradiation. Overall
survival did not differ between groups (hazard ratio (HR) 0.98 [0.55–1.73], p = 0.94). There were fewer
neck metastases (HR 0.34 [0.15–0.77]; p = 0.01), as well as fewer local recurrences (HR 0.41 [0.19–0.89];
p = 0.02) under adjuvant RT. For QL, irradiated patients showed higher values for the symptom scale
pain after 0.5, two, and three years (all p < 0.05). After six months and three years, irradiated patients
reported higher symptom burdens (impaired swallowing, speech, as well as teeth-related problems
(all p < 0.05)). Patients in the RT group had significantly more problems with mouth opening after
six months, one, and two years (p < 0.05); (4) Conclusions: Adjuvant RT in patients with early SCC of
the oral cavity and oropharynx does not seem to influence overall survival, but it positively affects
progression-free survival. However, irradiated patients report a significantly decreased QL up to
three years after therapy compared to the observation group
Small intestinal mucosa expression of putative chaperone fls485
<p>Abstract</p> <p>Background</p> <p>Maturation of enterocytes along the small intestinal crypt-villus axis is associated with significant changes in gene expression profiles. <it>fls485 </it>coding a putative chaperone protein has been recently suggested as a gene involved in this process. The aim of the present study was to analyze <it>fls48</it>5 expression in human small intestinal mucosa.</p> <p>Methods</p> <p><it>fls485 </it>expression in purified normal or intestinal mucosa affected with celiac disease was investigated with a molecular approach including qRT-PCR, Western blotting, and expression strategies. Molecular data were corroborated with several <it>in situ </it>techniques and usage of newly synthesized mouse monoclonal antibodies.</p> <p>Results</p> <p>fls485 mRNA expression was preferentially found in enterocytes and chromaffine cells of human intestinal mucosa as well as in several cell lines including Rko, Lovo, and CaCo2 cells. Western blot analysis with our new anti-fls485 antibodies revealed at least two fls485 proteins. In a functional CaCo2 model, an increase in fls485 expression was paralleled by cellular maturation stage. Immunohistochemistry demonstrated fls485 as a cytosolic protein with a slightly increasing expression gradient along the crypt-villus axis which was impaired in celiac disease Marsh IIIa-c.</p> <p>Conclusions</p> <p>Expression and synthesis of fls485 are found in surface lining epithelia of normal human intestinal mucosa and deriving epithelial cell lines. An interdependence of enterocyte differentiation along the crypt-villus axis and fls485 chaperone activity might be possible.</p