In Process Citation Stanescu-Siegmund, N; Brunner, H; Schmidt, S A
RöFo : Fortschritte auf dem Gebiet der Röntgenstrahlen und der bildgebende Verfahren
188, Številka:
5
Journal Article
Time has always had a special status in physics because of its fundamental role in specifying the regularities of nature and because of the extraordinary precision with which it can be measured. This ...precision enables tests of fundamental physics and cosmology, as well as practical applications such as satellite navigation. Recently, a regime of operation for atomic clocks based on optical transitions has become possible, promising even higher performance. We report the frequency ratio of two optical atomic clocks with a fractional uncertainty of 5.2 x 10⁻¹⁷. The ratio of aluminum and mercury single-ion optical clock frequencies νAl⁺/νHg⁺ is 1.052871833148990438(55), where the uncertainty comprises a statistical measurement uncertainty of 4.3 x 10⁻¹⁷, and systematic uncertainties of 1.9 x 10⁻¹⁷ and 2.3 x 10⁻¹⁷ in the mercury and aluminum frequency standards, respectively. Repeated measurements during the past year yield a preliminary constraint on the temporal variation of the fine-structure constant α of Formula: see text.
Hintergrund:
Eine langfristige, enterale Ernährung ist bei neurologischen Frührehabilitanden aufgrund ausgeprägter Dysphagien oft erforderlich. Gastrointestinale Intoleranzen wie z.B. Diarrhöen sind ...dabei häufige Komplikationen, belasten den Patienten und führen häufig zu einer Unterbrechung bzw. Reduktion der Nährstoffzufuhr. Eine lebensmittelbasierte Sondennahrung könnte jedoch Diarrhöen reduzieren. Daher wurde in einer offenen, multizentrischen, kontrollierten und randomisierten Interventionsstudie die Verträglichkeit einer lebensmittelbasierten Sondennahrung im Vergleich zu einer handelsüblichen Sondennahrung anhand der Häufigkeit dünnflüssiger Darmentleerungen untersucht.
Methoden:
Neurologische Patienten (n = 117) mit einer Indikation zur längerfristigen Ernährung mittels Magensonde erhielten über 30 Tage entweder eine lebensmittelbasierte Sondennahrung (HIPP; Interventionsgruppe n = 59) oder eine handelsübliche Sondennahrung auf Basis pulverförmiger Rohstoffe (Fresenius; Kontrollgruppe n = 58). Zur Bewertung der gastrointestinalen Toleranz wurde täglich die Anzahl sowie die Qualität der Darmentleerungen anhand der Bristol-Stool-Chart (BSS) erfasst.
Ergebnisse:
Die Patienten der Interventionsgruppe zeigten am häufigsten (37,1%) normal geformte Stuhlgänge (BSS Typ 4), wohingegen die Patienten der Kontrollgruppe am häufigsten (36,5%) dünnflüssige Darmentleerungen (BSS Typ 7) aufwiesen. Die Patienten der Interventionsgruppe wiesen im Vergleich zur Kontrollgruppe signifikant seltener dünnflüssige Darmentleerungen auf (Tabelle 1).
Intervention
Kontrolle
ANCOVA
Mittelwert (adj.)
6,5
17,1
p < 0,0001
95% CI
2,7; 10,3
13,4; 20,8
Zusammenfassung:
Eine enterale Ernährung auf der Basis von Lebensmitteln führt zu signifikant weniger dünnflüssigen Darmentleerungen bei neurologischen Frührehabilitanden. Dies könnte den pflegerischen Aufwand und Behandlungskosten reduzieren. Ob sich zusätzlich ein positiver Effekt auf die rehabilitative Behandlung ergibt, soll Gegenstand zukünftiger Studien sein.
Chemokine CXCL12 and receptor CXCR4 control multiple steps in primary tumor growth and metastasis in breast cancer and more than 20 other human malignancies. Mechanisms that regulate availability of ...CXCL12 in tumor microenvironments will substantially impact cancer progression and ongoing efforts to target the CXCL12-CXCR4 pathway for cancer chemotherapy. We used dual luciferase imaging to investigate CXCR7-dependent scavenging of CXCL12 in breast tumors in vivo and quantify effects of CXCR7 on tumor growth and metastasis of a separate population of CXCR4+ breast cancer cells. In a mouse xenograft model of human breast cancer, in vivo imaging showed that malignant cells expressing CXCR7 reduced bioluminescent CXCL12 secreted in the primary tumor microenvironment. Capitalizing on sensitive detection of bioluminescent CXCL12, we also demonstrated that CXCR7+ cells reduced amounts of chemokine released from orthotopic tumors into the circulation. Immunofluorescence staining of human primary breast cancers showed expression of CXCR4 and CXCR7 on malignant cells in ≈30% of cases. In most cases, CXCR4 and CXCR7 predominantly were expressed on separate populations of malignant cells in a tumor. We modeled these cases of human breast cancer by co-implanting tumor xenografts with CXCR4+ breast cancer cells, human mammary fibroblasts secreting CXCL12, and CXCR7+ or control breast cancer cells. Bioluminescence imaging showed that CXCR7+ breast cancer cells enhanced proliferation of CXCR4+ breast cancer cells in orthotopic tumors and spontaneous metastases. Treatment with a small-molecule inhibitor of CXCR7 chemokine limited the growth of CXCR4+ breast cancer cells in tumors that also contained malignant CXCR7+ cells. These studies establish a new in vivo imaging method to quantify chemokine scavenging by CXCR7 in the tumor microenvironment and identify that CXCR7+ cells promote growth and metastasis of CXCR4+ breast cancer cells.
We assess evidence relevant to Earth's equilibrium climate sensitivity per doubling of atmospheric CO2, characterized by an effective sensitivity S . This evidence includes feedback process ...understanding, the historical climate record, and the paleoclimate record. An S value lower than 2 K is difficult to reconcile with any of the three lines of evidence. The amount of cooling during the Last Glacial Maximum provides strong evidence against values of S greater than 4.5 K. Other lines of evidence in combination also show that this is relatively unlikely. We use a Bayesian approach to produce a probability density (PDF) for S given all the evidence, including tests of robustness to difficult‐to‐quantify uncertainties and different priors. The 66% range is 2.6‐3.9 K for our Baseline calculation, and remains within 2.3‐4.5 K under the robustness tests; corresponding 5‐95% ranges are 2.3‐4.7 K, bounded by 2.0‐5.7 K (although such high‐confidence ranges should be regarded more cautiously). This indicates a stronger constraint on S than reported in past assessments, by lifting the low end of the range. This narrowing occurs because the three lines of evidence agree and are judged to be largely independent, and because of greater confidence in understanding feedback processes and in combining evidence. We identify promising avenues for further narrowing the range in S , in particular using comprehensive models and process understanding to address limitations in the traditional forcing‐feedback paradigm for interpreting past changes.
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