1,721,659 research outputs found
Codimension two min-max minimal submanifolds from PDEs
No full textA fruitful method to construct min-max minimal hypersurfaces, in an ambient closed Riemannian manifold, is given by the Allen-Cahn functional and its natural rescalings. This approach produces minimal hypersurfaces as limiting interfaces in a phase transition between two different states. A natural attempt to carry out this in codimension two is to use the simplified Ginzburg-Landau functional (with no magnetic potential and no external field) and hope (roughly speaking) to capture a minimal submanifold as a limit of the vortices, as the repulsion parameter tends to infinity. It is known since two decades that one always gets a stationary rectifiable varifold in the limit, but it is an open problem to establish its integrality.
After briefly describing the difficulties arising with this functional, we will see how they disappear looking instead at the Yang-Mills-Higgs action (or the full Ginzburg-Landau free energy), with the natural rescalings preserving self-duality, first proposed by Hong-Jost-Struwe in the two-dimensional setting. We will discuss the features of this relaxation of the codimension-two area, which become strikingly similar to those of Allen-Cahn: in particular, integrality of the limit varifold and exponential decay of the energy density (away from vortices) do hold. We also describe how to construct a (codimension two) min-max integer stationary varifold in any ambient closed manifold using this approach. This is joint work with Daniel Stern (Princeton University - University of Toronto)
Quantization and non-quantization of energy for higher-dimensional Ginzburg-Landau vortices
Full text linkGiven a family of critical points for the
complex Ginzburg--Landau energies \begin{align*}
&E_\epsilon(u)=\int_{M}\left(\frac{|du|^2}{2}+\frac{(1-|u|^2)^2}{4\epsilon^2}\right),
\end{align*} on a manifold , with natural energy growth
, it is known that the vorticity
sets converge subsequentially to the support
of a stationary, rectifiable -varifold in the interior,
characterized as the concentrated portion of the limit of the normalized energy
measures.
When or the solutions are energy-minimizing, it is known
moreover that this varifold is integral; i.e., the -density
of takes values in at -a.e. . In the present paper, we show that for a general family of critical points
with in dimension ,
this energy quantization phenomenon only holds where the density is less than
: namely, we prove that the density of the limit
varifold takes values in at -a.e. , and
show that this is sharp, in the sense that for any and , there exists a family of critical points
for in the ball with concentration varifold given
by an -plane with density .Comment: this is the version published on Ars Inveniendi Analytic
Minimal submanifolds from the abelian Higgs model
No full textISSN:0020-9910ISSN:1432-1297ISSN:1432-129
Development of a rapid detection system for orthopoxviruses
No full textDie Famile der Orthopockenviren umschließt neben den zwar ausgerotteten, im Falle
einer nicht auszuschließenden bioterroristischen Ausbringung aber hochgefährlichen
Variolaviren weitere humanpathogene Viren wie das Affenpocken-, das Kuhpockensowie
das Vacciniavirus. Als zoonotische Erreger endemisch in Zentral- und Westafrika,
Europa sowie Südamerika, verursachen Sie lokal begrenzt bis systemisch verlaufende
pustuläre Erkrankungen, welche in Einzelfällen bis zum Tod führen können.
Aufgrund des seltenen Auftretens sind deutschlandweit nur wenige Speziallabore wie
das Robert Koch-Institut in der Lage, den Nachweis einer Orthopockenvirusinfektion
anhand serologischer, Nukleinsäure- oder Partikel-basierter Nachweisverfahren zu
erbringen. Ein im Falle einer bioterroristischen Freisetzung von Variolaviren notwendiges
schnelles, sensitives und einfach durchzuführendes Detektionssystem existiert
bis heute jedoch nicht.
Um diese Lücke zu schließen, war das Ziel dieser Arbeit die Entwicklung eines
Antikörper-basierten Schnelldetektionssystems zum Nachweis von Orthopockenviren.
Durch Testung Oberflächenprotein-spezifischer polyklonaler Antikörper konnte
gezeigt werden, dass das Attachment-Protein A27 am geeignetsten zur Induktion Detektions-
optimierter Antikörper ist. In einem mehrstufigen Screeningverfahren wurden
daher monoklonale Antikörper gegen A27 generiert, deren Bindungsepitope und
Bindungskinetik mittels Peptid-Epitopmapping und Oberflächenplasmonresonanz-
Messung bestimmt wurden. Hierbei zeigte sich, dass gute Zugänglichkeit der Bindungsepitope
sowie schnelle und multivalente Bindung entscheidend für Detektionsoptimierte
Antikörper waren. Die beiden besten Antikörper wurden schließlich auf
der Abicap Vor-Ort-Detektionsplattform implementiert und bezüglich Sensitivität
und Spezifität beim Orthopockenvirusnachweis charakterisiert. Als Ansatzpunkt für
potenzielle Weiterentwicklungen wurden diese zusätzlich in Form rekombinanter single
chain fragment variable Antikörper exprimiert und getestet.
Das etablierte Detektionssystem war in der Lage, alle getesteten humanpathogenen
Orthopockenviren mit hoher Sensitivität von bis zu 1,75×10^2 PFU/ml in 45 Minuten
zu detektieren, wobei der Nachweis aus klinischem Material sowie einem verblindetem
Probenpanel ohne Kreuzreaktivitäten möglich war. Durch die schnelle und einfache
Durchführbarkeit bei gleichzeitig hoher Sensitivität eignet sich das Abicap-System
sehr gut für die Vor-Ort-Testung sowohl bioterroristischer als auch klinischer Proben.
Darüber hinaus können die in dieser Arbeit gewonnenen Erkenntnisse zur Generierung
Detektions-optimierter Antikörper auf anderer Erreger übertragen werden.Besides the eradicated Variola virus, which in the case of an unlikely but non excludable
bioterrorist attack nevertheless remains highly dangerous, the Orthopoxvirus
family contains further viruses pathogenic for humans like Monkeypox, Cowpox,
and Vaccinia virus. As zoonotic agents, they are endemic in Central and Western
Africa, Europe, and South America, causing mainly local to systemic pustular
diseases which, in rare cases, can lead to death. Due to their rare incidence, only
a few specialized laboratories like the Robert Koch-Institute are able to diagnose
orthopoxvirus infections via serological, nucleic acid, or virus-particle based detection
methods. However, to date there is no fast, sensitive and simple rapid on-site
detection system, which in the case of bioterrorist release of Variola virus would be
needed.
To fill this gap, the aim of this work was to develop an antibody-based rapid detection
system for Orthopoxviruses. By testing surface protein-specific polyclonal antibodies,
we could show that the attachment protein A27 is most suited for induction
of detection-optimized antibodies. Hence, a multi-level screening was used to generate
A27-specific monoclonal antibodies whose binding epitopes and kinetics were
determined by peptide epitope mapping and surface plason resonance measurement.
Hereby, high accessibility of binding epitopes as well as rapid and multivalent binding
were hallmarks for detection-optimized antibodies. Finally, two outperforming antibodies
were implemented on the Abicap onsite detection platform and characterized
regarding their sensitivity and specificity in Orthopoxvirus detection. Additionally,
as a starting point for further optimization, both antibodies were expressed as recombinant
single-chain variable fragments.
The established rapid detection system was able to detect all tested Orthopoxviruses
pathogenic to humans with high sensitivity down to 1.75×10^2 PFU/ml within 45
minutes. Detection was possible from clinical samples and a blinded sample panel
without cross-reactivity. Due to rapid and simple handling at sustained high sensitivity,
the Abicap-platform is highly suited for onsite testing in a bioterrorist as well
as a clinical context. Furthermore, findings regarding the generation of detectionoptimized
antibodies gained during this work could be transferred to other agents
Structural and variable-temperature NMR studies of 9-diisopropylphosphanylanthracenes and 9,10-bis(diisopropylphosphanyl)anthracenes and their oxidation products
No full textThe diisopropylphosphanyl-substituted anthracenes i-Pr(2)P(C(14)H(9)) (1a), i-Pr(2)P(C(14)H(8))Br (2a), and (i-Pr(2)P)(2)(C(14)H(8)) (3a) and some of their oxidation products were prepared from 9-bromoanthracene and 9,10-dibromoanthracene, respectively. Low-temperature (1)H NMR spectra of the 9-monophosphanyl-substituted anthracenes la and 2a are in accordance with a staggered conformer, while above room temperature dynamic processes occur. The low-temperature NMR spectrum of the 9,10-diphosphanylanthracene 3a indicates the presence of two different rotational isomers. The rotational barrier for la was determined from variable-temperature (1)H NMR spectra to be 56 kJ mol(-1) (Delta G(298K)). The crystal structure determinations show the solid-state conformers to be consistent with the prevailing conformer at low temperature
Etude du suivi régional de la qualité de service par les méthodes d'analyse de données
No full textJambu Michel, Tan Suy Ho, Stern Daniel, Birenbaum Jean. Etude du suivi régional de la qualité de service par les méthodes d'analyse de données. In: NETCOM : Réseaux, communication et territoires / Networks and Communication Studies, vol. 2 n°2, décembre 1988. Le colloque international « Communications et territoires », Issy-les-Moulineaux / Paris-Sorbonne, 21-23 janvier 1988. pp. 144-191
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Solvent-Separated and Contact Ion Pairs of Parent Lithium Trimethyl Zincate
No full textDeutsche Forschungsgemeinschaf
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