Incidence of lymph node metastases after piecemeal laser-surgical and en bloc cold steel resection of auricular VX2 carcinoma. A comparative study.

The CO2 laser surgery has become a widely used clinical treatment in otorhinolaryngology. In advanced neoplastic disease of the head and neck it is often difficult and even impossible to expose well the whole tumor through the surgical laryngoscope. In such cases the tumor is usually divided with the CO2 laser in several parts, which are excised separately. This approach seems opposed to the basic principles of oncologic surgery, where the tumor should not be touched in order to avoid local recurrences or metastatic spread. The proponents of the piecemeal resections refer back to few morphological and clinical studies, which show no evidence of increased incidence of metastases after the piecemeal resection. On this background the aim of the present study was to compare the piecemeal laser surgical complete (R0) resection with cold steel complete (R0) en bloc resection of tumors in an animal model. For both surgical approaches the incidence of local recurrences, regional and distant metastases had to be compared. After randomization to the both study arms in 143 male New Zealand White rabbits a VX2 squamous cell carcinoma was induced on the auricle. On day 8 a complete resection of the tumour was performed: for the first group - with cold steel resection en bloc; for the second group the cancer was transected by the CO2 laser following which it was removed in two pieces - piecemeal laser-surgical resection. On the 42nd postoperative day all animals were sacrificed and subjected to evaluation of the tumoral spread. Compared on the incidence of LN metastases the two therapeutic groups showed significant differences. Twenty-five percent of the animals with en bloc cold steel had metastases to regional lymph nodes, whereas forty-seven percent of the laser piecemeal group had metastatic nodal involvement. The incidence of distant metastases was similar for both study groups - 12.3% for the en block resection group and 7.7% for the piecemeal laser resection group. In this experimental setting the piecemeal laser surgical resection achieved better local results, but lead to more metastases (mainly lymphatic ones), than the cold steal en bloc resection. However, it is unlikely that tumor cells disseminated from the resection line itself caused this difference, as the vessels here were occluded by the laser. Mechanisms, which could explain the observed difference include dissemination through the walls of the intratumoral or peritumoral lymphatics. Piecemeal laser resection may decompress intratumoral pressure and release intra and peritumoral lymphatics, causing a flood of tumor emboli. Changes in the permeability and the lymph/blood flow caused by the local laser heat could have similar effect. Additionally mechanical trauma to the tumor mass itself or explosion-like tumor cell spread into the lymphatic network due to the applied laser energy could also precipitate metastases

Potentielle Auswirkung der Genese der Schwerhörigkeit aud die subjektiv empfundene Lebensqualität

Die Pilotstudie der Hals-Nasen und Ohrenklinik der Universität Marburg hatte das Ziel den Einfluss der Ursache der Schwerhörigkeit auf die subjektiv empfundene Lebensqualität der Patienten genauer zu beleuchten. Dazu wurden 100 Patienten anhand der objektiven klinischen Daten in vier Gruppen unterteilt ( Hörsturz, chronische Otitis media, M Menière und Otosklerose).Anhand der Königsteiner Richtlinien wurde der objektive Schweregrad bestimmt. Zusätzlich wurden die Patienten mit dem neu entwickelten Fragebogen zur Erfassung der Lebensqualität (FELAS) bezüglich der subjektiven Lebensqualität in den Rubriken Kommunikation, Aktivitätsminderung und emotionale Einbußen eruiert. In einem ersten Schritt wurden die Gruppen unterschiedlicher Genese mittels der multifaktoriellen Varianzanalsyse auf Unterschiede zwischen den Gruppen bezüglich der Lebensqualität untersucht. Dabei ließen sich keine signifikanten Unterschiede feststellen. Die Ursache der Schwerhörigkeit scheint demnach keinen Einfluss auf die Lebensqualität schwerhöriger Patienten zu haben. Zur Klärung der Frage, ob die klinischen Einteilungen mit der subjektiven Einschätzung korrelieren wurde eine Rang-Korrelation nach Spearman/Brown durchgeführt. Die dabei berechneten Korrelationen lassen eine Einschätzung der Lebensqualität auf Grund der objektiven Daten der klinischen Einteilung nicht zu

Parameter estimation with mixed quantum states

We consider quantum enhanced measurements with initially mixed states. We show very generally that for any linear propagation of the initial state that depends smoothly on the parameter to be estimated, the sensitivity is bound by the maximal sensitivity that can be achieved for any of the pure states from which the initial density matrix is mixed. This provides a very general proof that purely classical correlations cannot improve the sensitivity of parameter estimation schemes in quantum enhanced measurement schemes.Comment: 6 page

Lagrangian circulation on the Southeast US Continental Shelf: Implications for larval dispersal and retention

Lagrangian characterization of continental shelf circulation provides estimates of the retention and transport of particulate and dissolved substances. In this paper, we quantify the retentive characteristics of the Southeast U.S. Continental Shelf by comparing observed and numerical (modeled) drifters released throughout 2000 and 2001. Agreement between the observed and computed drifter trajectories shows that retention on this shelf can be up to two months at any point during the year. These results have important implications for ecological and fisheries applications and indicate that the populations of marine organisms in this region might be relatively closed (i.e., with weak exchange) during some periods of the year

A novel, low-volume method for organ culture of embryonic kidneys that allows development of cortico-medullary anatomical organization

Here, we present a novel method for culturing kidneys in low volumes of medium that offers more organotypic development compared to conventional methods. Organ culture is a powerful technique for studying renal development. It recapitulates many aspects of early development very well, but the established techniques have some disadvantages: in particular, they require relatively large volumes (1-3 mls) of culture medium, which can make high-throughput screens expensive, they require porous (filter) substrates which are difficult to modify chemically, and the organs produced do not achieve good cortico-medullary zonation. Here, we present a technique of growing kidney rudiments in very low volumes of medium-around 85 microliters-using silicone chambers. In this system, kidneys grow directly on glass, grow larger than in conventional culture and develop a clear anatomical cortico-medullary zonation with extended loops of Henle. © 2010 Sebinger et al

Report from the Expert Panel on the evaluation of the VRZs during the 2018/19 fishing season

In July 2018 ARK (the Association of Responsible Krill harvesting companies) launched a set of voluntary measures, known as ARK’s Commitment, which were proposed to improve the long-term sustainability of the krill fishery. The Commitment was initiated with support from Greenpeace, WWF and The Pew Charitable Trusts as a precautionary action whilst CCAMLR developed spatial management of the krill fishery in Area 48. The Commitment, which took the form of Voluntary Restriction Zones (VRZs), was implemented for the 2018-19 fishing season. The krill fishing fleet associated with ARK agreed to avoid fishing in an area of up to 40 km from penguin colonies in Subarea 48.1 during the penguin breeding season

Recurrence for discrete time unitary evolutions

We consider quantum dynamical systems specified by a unitary operator U and an initial state vector \phi. In each step the unitary is followed by a projective measurement checking whether the system has returned to the initial state. We call the system recurrent if this eventually happens with probability one. We show that recurrence is equivalent to the absence of an absolutely continuous part from the spectral measure of U with respect to \phi. We also show that in the recurrent case the expected first return time is an integer or infinite, for which we give a topological interpretation. A key role in our theory is played by the first arrival amplitudes, which turn out to be the (complex conjugated) Taylor coefficients of the Schur function of the spectral measure. On the one hand, this provides a direct dynamical interpretation of these coefficients; on the other hand it links our definition of first return times to a large body of mathematical literature.Comment: 27 pages, 5 figures, typos correcte

An outlook on self-assessment of homework assignments in higher mathematics education

Abstract Background We discuss first experiences with a new variant of self-assessment in higher mathematics education. In our setting, the students of the course have to mark a part of their homework assignments themselves and they receive the corresponding credit without that any later changes are carried out by the teacher. In this way, we seek to correct the imbalance between student-centered learning arrangements and assessment concepts that keep the privilege to grade (or mark) completely with the teacher. Results We present results in the form of student feedback from a course on functional analysis for third- and fourth-year students. Moreover, we analyze marking results from two courses on real analysis. Here, we compare tasks marked by the teacher and tasks marked by the students. Conclusions Our experiments indicate that students can benefit from self-assessment tasks. The success depends, however, on many different factors. Promising for self-assessment seem to be small learning groups and tasks in which a priori weaker students can catch up with stronger students by increasing their practising time

Quantum correlated twin atomic beams via photo-dissociation of a molecular Bose-Einstein condensate

We study the process of photo-dissociation of a molecular Bose-Einstein condensate as a potential source of strongly correlated twin atomic beams. We show that the two beams can possess nearly perfect quantum squeezing in their relative numbers.Comment: Corrected LaTeX file layou

The role of hydrodynamics in explaining variability in fish populations

A review of the physical processes present in coastal regions and their effect on pelagic stages of flatfish populations is presented. While quantitative understanding of processes affecting cross-shelf transport and exchange continues to be a fundamental problem shared by physical oceanographers and fisheries scientists studying the early life history of flatfish, advances in hydrodynamic and coupled physical-biological models have made it possible to begin to examine population-level implications of environmental processes. There is now a need to rank these processes in terms of their impact on recruit strength. Existing paradigms provide testable frameworks for explaining the role of physical variability in the observed population patterns, abundance and variability. Identifying explicit links between physical variability and recruitment could result in new approaches to fisheries management strategies