2,497 research outputs found

    The Impact of an Antireflux Catheter on Target Volume Particulate Distribution in Liver-Directed Embolotherapy: A Pilot Study

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    AbstractPurposeTo determine if there are differences in hepatic distribution of embolic particles following infusion with a standard end-hole catheter versus an antireflux microcatheter.Materials and MethodsThis prospective study included nine patients (age, 48–86 y) enrolled for treatment of hepatocellular carcinoma (n = 6), liver-dominant metastatic disease (n = 2), or intrahepatic cholangiocarcinoma (n = 1) with resin yttrium-90 (90Y) microspheres. Before 90Y treatment, each patient received two same-day sequential lobar infusions of technetium 99m (99mTc) macroaggregated albumin (MAA) via a conventional end-hole catheter and an antireflux microcatheter positioned at the same location. Differences in technetium 99m–MAA distribution within tumor and nontarget sites were evaluated by single-photon emission computed tomography (SPECT) on a qualitative and semiquantitative basis. The antireflux microcatheter was used for the ensuing 90Y treatment, with posttreatment 90Y positron emission tomography/computed tomography to assess distribution of 90Y microspheres.ResultsDecreases in hepatic nontarget embolization were found in all patients when the antireflux catheter was used. These decreases ranged from a factor of 0.11 to a factor of 0.76 (mean, 0.42; σ = 0.19), representing a 24%–89% reduction. Increased tumor deposition was also noted in all patients, ranging from a factor of 1.33 to a factor of 1.90 (mean, 1.68; σ = 0.20), representing a relative increase of 33%–90%. Both findings were statistically significant (P < .05).ConclusionsAlthough this pilot study identified differences in the downstream distribution of embolic particles when the antireflux catheter was used, further investigation is needed to determine if these findings are reproducible in a larger patient cohort and, if so, whether they are associated with any clinical impact

    Computational simulation of the predicted dosimetric impact of adjuvant yttrium-90 PET/CT-guided percutaneous ablation following radioembolization

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    Background: 90Y PET/CT post-radioembolization imaging has demonstrated that the distribution of 90Y in a tumor can be non-uniform. Using computational modeling, we predicted the dosimetric impact of post-treatment 90Y PET/CT-guided percutaneous ablation of the portions of a tumor receiving the lowest absorbed dose. A cohort of fourteen patients with non-resectable liver cancer previously treated using 90Y radioembolization were included in this retrospective study. Each patient exhibited potentially under-treated areas of tumor following treatment based on quantitative 90Y PET/CT. 90Y PET/CT was used to guide electrode placement for simulated adjuvant radiofrequency ablation in areas of tumor receiving the lowest dose. The finite element method was used to solve Penne’s bioheat transport equation, coupled with the Arrhenius thermal cell-death model to determine 3D thermal ablation zones. Tumor and unablated tumor absorbed-dose metrics (average dose, D50, D70, D90, V100) following ablation were compared, where D70 is the minimum dose to 70% of tumor and V100 is the fractional tumor volume receiving more than 100 Gy. Results: Compared to radioembolization alone, 90Y radioembolization with adjuvant ablation was associated with predicted increases in all tumor dose metrics evaluated. The mean average absorbed dose increased by 11.2 ± 6.9 Gy. Increases in D50, D70, and D90 were 11.0 ± 6.9 Gy, 13.3 ± 10.9 Gy, and 11.8 ± 10.8 Gy, respectively. The mean increase in V100 was 7.2 ± 4.2%. All changes were statistically significant (P \u3c 0.01). A negative correlation between pre-ablation tumor volume and D50, average dose, and V100 was identified (ρ \u3c − 0.5, P \u3c 0.05) suggesting that adjuvant radiofrequency ablation may be less beneficial to patients with large tumor burdens. Conclusions: This study has demonstrated that adjuvant 90Y PET/CT-guided radiofrequency ablation may improve tumor absorbed-dose metrics. These data may justify a prospective clinical trial to further evaluate this hybrid approach

    Kapitalstrukturen börsennotierter Aktiengesellschaften - Deutschland und USA im Vergleich

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    Bisherige Evidenz ĂŒber Kapitalstrukturunterschiede zwischen Deutschland und den USA deutet auf eine durchschnittlich höhere Verschuldung deutscher Unternehmen hin. Die vergangenen Jahre waren in Deutschland jedoch durch eine Förderung der Eigenkapitalfinanzierung seitens des deutschen Gesetzgebers und der Regulierungsbehörden geprĂ€gt. Die vorliegende Arbeit untersucht, inwieweit sich diese Änderungen tatsĂ€chlich auf den Verschuldungsgrad deutscher Unternehmen auswirken und ob es zu einer AnnĂ€herung an amerikanische Unternehmen kommt. Zu diesem Zweck werden durchschnittliche Verschuldungsgrade von US-amerikanischen und deutschen börsennotierten Gesellschaften ĂŒber einen Zeitraum von 10 Jahren verglichen. Die Untersuchung zeigt, dass diese Änderungen vor allem den Verschuldungsgrad von Unternehmen beeinflusst haben, die erst in den letzten Jahren an einer deutschen Börse notiert wurden. Bei am deutschen Kapitalmarkt etablierten Unternehmen hingegen lĂ€sst sich keine aufgrund der neuen Rahmenbedingungen vorgenommene Anpassung der Verschuldungspolitik erkennen. Abstract Existing comparative evidence on corporate capital structure decisions in the U.S. and Germany traditionally reveals that German firms chose substantially higher levels of debt financing. Within the past years, however, Germany has experienced repeated initiatives by both legislative and regulatory bodies to promote equity finance. This paper tries to shed first light on how these initiatives affect the debt-equity-decision of German corporations and whether a convergence of German leverage levels to Anglo-American financing patterns can be observed. For this purpose we compare capital structures for a panel of U.S. and German public corporations over the past 10 years. The obtained evidence suggests that aggregate leverage ratios do indeed converge. Yet this development is primarily driven by recent German IPOs which seem to respond to the revamped institutional setting by choosing higher levels of equity. Established German corporations, by contrast, do not seem to have systematically adapted their financing patterns over the past decade

    Wheat photosystem II heat tolerance responds dynamically to short- and long-term warming

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    Wheat photosynthetic heat tolerance can be characterized using minimal chlorophyll fuorescence to quantify the critical temperature (Tcrit) above which incipient damage to the photosynthetic machinery occurs. We investigated intraspecies variation and plasticity of wheat Tcrit under elevated temperature in feld and controlled-environment experiments, and assessed whether intraspecies variation mirrored interspecifc patterns of global heat tolerance. In the feld, wheat Tcrit varied diurnally—declining from noon through to sunrise—and increased with phenological deïżœvelopment. Under controlled conditions, heat stress (36 °C) drove a rapid (within 2 h) rise in Tcrit that peaked after 3–4 d. The peak in Tcrit indicated an upper limit to PSII heat tolerance. A global dataset [comprising 183 Triticum and wild wheat (Aegilops) species] generated from the current study and a systematic literature review showed that wheat leaf Tcrit varied by up to 20 °C (roughly two-thirds of reported global plant interspecies variation). However, unlike global patterns of interspecies Tcrit variation that have been linked to latitude of genotype origin, intraspecifc variation in wheat Tcrit was unrelated to that. Overall, the observed genotypic variation and plasticity of wheat Tcrit suggest that this trait could be useful in high-throughput phenotyping of wheat photosynthetic heat toleranc

    Dimensionality effects in restricted bosonic and fermionic systems

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    The phenomenon of Bose-like condensation, the continuous change of the dimensionality of the particle distribution as a consequence of freezing out of one or more degrees of freedom in the low particle density limit, is investigated theoretically in the case of closed systems of massive bosons and fermions, described by general single-particle hamiltonians. This phenomenon is similar for both types of particles and, for some energy spectra, exhibits features specific to multiple-step Bose-Einstein condensation, for instance the appearance of maxima in the specific heat. In the case of fermions, as the particle density increases, another phenomenon is also observed. For certain types of single particle hamiltonians, the specific heat is approaching asymptotically a divergent behavior at zero temperature, as the Fermi energy Ï”F\epsilon_{\rm F} is converging towards any value from an infinite discrete set of energies: Ï”ii≄1{\epsilon_i}_{i\ge 1}. If Ï”F=Ï”i\epsilon_{\rm F}=\epsilon_i, for any i, the specific heat is divergent at T=0 just in infinite systems, whereas for any finite system the specific heat approaches zero at low enough temperatures. The results are particularized for particles trapped inside parallelepipedic boxes and harmonic potentials. PACS numbers: 05.30.Ch, 64.90.+b, 05.30.Fk, 05.30.JpComment: 7 pages, 3 figures (included

    Leveraging Generative AI for Clinical Evidence Summarization Needs to Ensure Trustworthiness

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    Evidence-based medicine promises to improve the quality of healthcare by empowering medical decisions and practices with the best available evidence. The rapid growth of medical evidence, which can be obtained from various sources, poses a challenge in collecting, appraising, and synthesizing the evidential information. Recent advancements in generative AI, exemplified by large language models, hold promise in facilitating the arduous task. However, developing accountable, fair, and inclusive models remains a complicated undertaking. In this perspective, we discuss the trustworthiness of generative AI in the context of automated summarization of medical evidence

    Possible realization of Josephson charge qubits in two coupled Bose-Einstein condensates

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    We demonstrate that two coupled Bose-Einstein condensates (BEC) at zero temperature can be used to realize a qubit which is the counterpart of Josephson charge qubits. The two BEC are weakly coupled and confined in an asymmetric double-well trap. When the "charging energy" of the system is much larger than the Josephson energy and the system is biased near a degeneracy point, the two BEC represent a qubit with two states differing only by one atom. The realization of the BEC qubits in realistic BEC experiments is briefly discussed.Comment: 4 pages; comments are welcome / Corrected typos in Eq. (16); a note adde

    Novel mutations in TARDBP (TDP-43) in patients with familial amyotrophic lateral sclerosis.

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    The TAR DNA-binding protein 43 (TDP-43) has been identified as the major disease protein in amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration with ubiquitin inclusions (FTLD-U), defining a novel class of neurodegenerative conditions: the TDP-43 proteinopathies. The first pathogenic mutations in the gene encoding TDP-43 (TARDBP) were recently reported in familial and sporadic ALS patients, supporting a direct role for TDP-43 in neurodegeneration. In this study, we report the identification and functional analyses of two novel and one known mutation in TARDBP that we identified as a result of extensive mutation analyses in a cohort of 296 patients with variable neurodegenerative diseases associated with TDP-43 histopathology. Three different heterozygous missense mutations in exon 6 of TARDBP (p.M337V, p.N345K, and p.I383V) were identified in the analysis of 92 familial ALS patients (3.3%), while no mutations were detected in 24 patients with sporadic ALS or 180 patients with other TDP-43-positive neurodegenerative diseases. The presence of p.M337V, p.N345K, and p.I383V was excluded in 825 controls and 652 additional sporadic ALS patients. All three mutations affect highly conserved amino acid residues in the C-terminal part of TDP-43 known to be involved in protein-protein interactions. Biochemical analysis of TDP-43 in ALS patient cell lines revealed a substantial increase in caspase cleaved fragments, including the approximately 25 kDa fragment, compared to control cell lines. Our findings support TARDBP mutations as a cause of ALS. Based on the specific C-terminal location of the mutations and the accumulation of a smaller C-terminal fragment, we speculate that TARDBP mutations may cause a toxic gain of function through novel protein interactions or intracellular accumulation of TDP-43 fragments leading to apoptosis
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