441 research outputs found
Chirality tubes along monopole trajectories
We classify the lattice by elementary 3-cubes which are associated to dual
links occupied by, or free of monopoles. We then compute the quark condensate,
the quark charge and the chiral density on those cubes. By looking at
distributions we demonstrate that monopole trajectories carry considerably more
chirality with respect to the free vacuum.Comment: LATTICE99(topology), 3 pages, eps figure
Are North Atlantic Alaria esculenta and A. grandifolia (Alariaceae, Phaeophyceae) conspecific?
Alaria (Alariaceae, Phaeophyceae) is a common genus of kelps in the northern hemisphere. Fourteen species are currently recognized, of which three, Alaria esculenta (L.) Greville, A. pylaii (Bory de Saint-Vincent) Greville and A. grandifolia J. Agardh, are reported for the cold-temperate North Atlantic Ocean. Alaria esculenta, the type species described originally from the North Atlantic, exhibits a range of biogeographically correlated morphotypes suggesting the possibility of multiple species, subspecies or hybrids. In Ireland we discovered an A. esculenta population with unusually long stipes resembling the type specimen of A. grandifolia described from Spitsbergen by J. Agardh in 1872. These and other plants of A. esculenta h om Ireland were compared with plants from Spitsbergen fitting the description of A. grandifolia, using sexual hybridization relative growth rate measurements and DNA sequence comparisons. Complete interfertility was observed between the different isolates. Three nucleotide substitutions (0.37%) were found in the rbcL and RuBisCo spacer of A. grandifolia, and two in the partial 18S rRNA gene and ITS1 sequences. The relative growth rate at 10 OC of an Irish self-cross was significantly lower than those of all the other crosses. Comparison of RuBisCo spacer sequences of the Spitsbergen A. grandifolia and six A. esculenta isolates showed that A. grandifolia was identical to A. esculenta from Halifax, Canada. The partial 18S rRNA gene and ITS1 sequence of A. grandifolia was identical to that of A. praelonga from Japan and differed by a single substitution from A. esculenta from Scotland and by two nucleotide substitutions from the isolate from Ireland. The intraspecific differences in A. esculenta, together with the hybridization and morphometric results, suggest that A. grandifolia is to be considered conspecific with A. esculenta, and that A. grandifolia is most probably a large deep-water morphological variant subspecies or ecotype of A. esculenta
Searching for KvBLL calorons in SU(3) lattice gauge field ensembles
We discuss Kraan - van Baal - Lee - Lu (KvBLL) solutions of the classical
Yang-Mills equations with temperature in the context of SU(3) lattice gauge
theory. We present discretized lattice versions of KvBLL solutions and other
dyonic structures, obtained by cooling in order to understand their variety and
signature. An analysis of the zero modes of the lattice Dirac operator for
different fermionic boundary conditions gives clear evidence for a KvBLL-like
background of finite T lattice subensembles with Q = +/-1. Using APE-smearing
we are able to study the topological charge density q(x) of the configurations
and to corroborate this interpretation.Comment: Presented at LATTICE 2003 (topology) by C. Gattringer and E.M.
Ilgenfritz, 6 page
New findings for topological excitations in SU(3) lattice gauge theory
We probe the SU(3) vacuum using eigenvectors of the Dirac operator with an
arbitrary phase for the temporal boundary condition. We consider configurations
with topological charge |Q| = 1 near the QCD phase transition and at low
temperatures on a torus. For all our ensembles we show that the zero-mode of
the Dirac operator changes its position as one changes the phase of the
boundary condition. For ensembles near the QCD phase transition our results
closely resemble the behavior of zero-modes for Kraan - van Baal solutions of
the classical Yang-Mills equations where the individual lumps are interpreted
as monopoles. Our findings near T_c and on the torus show that for both cases
an excitation with topological charge |Q| = 1 is built from several separate
lumps.Comment: Typo corrected. To appear in Nuclear Physics
A comprehensive picture of topological excitations in finite temperature lattice QCD
We study spectra, localization properties and local chirality of eigenvectors
of the lattice Dirac operator. We analyze ensembles of quenched SU(3)
configurations on both sides of the QCD phase transition. Our Dirac operator is
a systematic expansion in path length of a solution of the Ginsparg-Wilson
equation. Analyzing the finite volume behavior of our observables and their
scaling with the gauge coupling we come up with a consistent picture of
topological excitations on both sides of the QCD phase transition. Our results
support the interpretation of the dominant gauge field excitations seen by the
Dirac operator as a fluid of instanton-like objects.Comment: 45 pages, 15 figures. r_0 is now used to set the physical scale.
Figure 7 has been redrawn to make it easier to interpret. To appear in
Nuclear Physics
Trastuzumab and first-line taxane chemotherapy in metastatic breast cancer patients with a HER2-negative tumor and HER2-positive circulating tumor cells:a phase II trial
Purpose: HER2 overexpressing circulating tumor cells (CTCs) are observed in up to 25% of HER2-negative metastatic breast cancer patients. Since targeted anti-HER2 therapy has drastically improved clinical outcomes of patients with HER2-positive breast cancer, we hypothesized that patients with HER2 overexpressing CTCs might benefit from the addition of trastuzumab to chemotherapy. Methods: In this single-arm, phase II trial, patients with HER2-positive CTCs received trastuzumab as addition to first-line treatment with taxane chemotherapy. Patients with detectable CTCs but without HER2 overexpression that received taxane chemotherapy only, were used as control group. The primary outcome measure was progression-free rate at 6 months (PFR6), with a target of 80%. In November 2022, the study was terminated early due to slow patient accrual. Results: 63 patients were screened, of which eight patients had HER2-positive CTCs and were treated with trastuzumab. The median number of CTCs was 15 per 7.5 ml of blood (range 1–131) in patients with HER2-positive CTCs, compared to median 5 (range 1–1047) in the control group. PFR6 was 50% in the trastuzumab group and 54% in the taxane monotherapy group, with no significant difference in median PFS (8 versus 9 months, p = 0.51). Conclusion: No clinical benefit of trastuzumab was observed, although this study was performed in a limited number of patients. Additionally, we observed a strong correlation between the number of evaluable CTCs and the presence of HER2-positive CTCs. We argue that randomized studies investigating agents that are proven to be solely effective in the HER2-positive patient group in patients with HER2-positive CTCs and HER2-negative tissue are currently infeasible. Several factors contribute to this impracticality, including the need for more stringent thresholds, and the rapidly evolving landscape of cancer treatments.</p
Trastuzumab and first-line taxane chemotherapy in metastatic breast cancer patients with a HER2-negative tumor and HER2-positive circulating tumor cells:a phase II trial
Purpose: HER2 overexpressing circulating tumor cells (CTCs) are observed in up to 25% of HER2-negative metastatic breast cancer patients. Since targeted anti-HER2 therapy has drastically improved clinical outcomes of patients with HER2-positive breast cancer, we hypothesized that patients with HER2 overexpressing CTCs might benefit from the addition of trastuzumab to chemotherapy. Methods: In this single-arm, phase II trial, patients with HER2-positive CTCs received trastuzumab as addition to first-line treatment with taxane chemotherapy. Patients with detectable CTCs but without HER2 overexpression that received taxane chemotherapy only, were used as control group. The primary outcome measure was progression-free rate at 6 months (PFR6), with a target of 80%. In November 2022, the study was terminated early due to slow patient accrual. Results: 63 patients were screened, of which eight patients had HER2-positive CTCs and were treated with trastuzumab. The median number of CTCs was 15 per 7.5 ml of blood (range 1–131) in patients with HER2-positive CTCs, compared to median 5 (range 1–1047) in the control group. PFR6 was 50% in the trastuzumab group and 54% in the taxane monotherapy group, with no significant difference in median PFS (8 versus 9 months, p = 0.51). Conclusion: No clinical benefit of trastuzumab was observed, although this study was performed in a limited number of patients. Additionally, we observed a strong correlation between the number of evaluable CTCs and the presence of HER2-positive CTCs. We argue that randomized studies investigating agents that are proven to be solely effective in the HER2-positive patient group in patients with HER2-positive CTCs and HER2-negative tissue are currently infeasible. Several factors contribute to this impracticality, including the need for more stringent thresholds, and the rapidly evolving landscape of cancer treatments.</p
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