Commensurate-incommensurate transition of cold atoms in an optical lattice

An atomic gas subject to a commensurate periodic potential generated by an optical lattice undergoes a superfluid--Mott insulator transition. Confining a strongly interacting gas to one dimension generates an instability where an arbitrary weak potential is sufficient to pin the atoms into the Mott state; here, we derive the corresponding phase diagram. The commensurate pinned state may be detected via its finite excitation gap and the Bragg peaks in the static structure factor.Comment: 4 pages, 2 figure

Activity of raltitrexed and gemcitabine in advanced pancreatic cancer

Background: Gemcitabine has evolved as standard therapy in advanced pancreatic cancer since the demonstration of a significant clinical benefit. Phase II trials have shown that gemcitabine can be successfully combined with thymidylate synthase (TS) inhibitors such as continuous-infusion 5-fluorouracil (5-FU). However, continuous-infusion 5-FU is inconvenient because of the need for a central venous access. The aim of this study was to assess the efficacy and safety of gemcitabine in combination with raltitrexed (Tomudex), a novel and selective TS inhibitor that has the advantage of a 3-weekly treatment interval and manageable toxicity. Patients and methods: Chemotherapy-naïve patients with measurable advanced pancreatic cancer were treated with raltitrexed 3 mg/m2 as a 15-min infusion on day 1 and gemcitabine 1000 mg/m2 on days 1 and 8, every 21 days. Results: Twenty-five eligible patients (17 male, eight female) with metastatic (21 patients) or locally advanced (four patients) disease entered the study. The median number of courses per patient was four (range 1-14). One patient was not evaluable for response. There were three partial remissions [12%; 95% confidence interval (CI) 2.6% to 31.2%] and nine stable disease situations (36%; 95% CI 18.0% to 57.5%), while the tumours of 12 patients (48%; 95% CI 27.8% to 68.7%) showed progressive disease after three treatment cycles. WHO grade 3/4 toxicity was rare and symptomatic in only one patient, who experienced grade 4 diarrhoea and grade 3 nausea and vomiting. Symptomatic benefit was seen in 12 patients. Median survival was 185 days (95% CI 129-241) with six patients still alive. Conclusions: The efficacy of raltitrexed plus gemcitabine is limited, but compares well with other chemotherapy treatment options in advanced pancreatic cancer. However, this combination is convenient and symptomatic toxicity is rare. Thus, raltitrexed and gemcitabine should be investigated further in combination with drugs interfering with specific molecular target

Die pyloruserhaltende Whipple-Operation: eine Alternative oder heutiger Standard beim Pankreaskarzinom?

Zusammenfassung: Grundlagen: Während die pyloruserhaltende Whipple-Operation eine gute Alternative zur klassischen Operation bei periampullären Tumoren darstellt, ist das Verfahren beim Pankreaskopfkarzinom umstritten. Methodik: Wir haben die Daten von 70 Patienten mit Pankreaskopfkarzinom prospektiv im Hinblick auf die Vorteile des operativen Vorgehens und in bezug auf Lebensqualität und Überlebenszeit untersucht. Ergebnisse: Bei 44 Patienten wurde eine pyloruserhaltende Resektion durchgeführt, bei 26 Fällen eine klassische Whipple-Operation (WO) mit Lymphadenektomie. Es gab bezüglich Alter, Geschlecht und Tumorstadium keine Unterschiede in den beiden Patientengruppen. Die Mittelwerte für die Operationszeit, Blutverlust und Hospitalisationsdauer betrugen bei der pyloruserhaltenden WO 382 min, 1125 ml und 18,3 Tage und bei der klassischen WO 460 min (p<0,05), 1650 ml (p<0,05) und 22 Tage. Die mediane Überprüfzeit betrug 17 Monate (Range 2 bis 28 Monate). In den ersten 3 Monaten postoperativ war der Gewichtsverlauf bei den Patienten mit pyloruserhaltender WO deutlich besser. Die mediane Überlebenszeit war nicht signifikant verschieden mit 12,2 Monaten für die Patienten mit pyloruserhaltender WO und 12,9 Monaten bei den Patienten mit klassischer WO. Schlußfolgerungen: Bei Patienten mit Pankreaskarzinom war die Lebensqualität und Gewichtszunahme postoperativ besser bei solchen mit pyloruserhaltender partieller Duodenopankreatektomie im Vergleich zur klassischen WO. Aufgrund dieser Ergebnisse, der intraoperativen Vorteile und bei gleicher Überlebenszeit sollte dieses Operationsverfahren beim Pankreaskarzinom, wenn immer möglich, bevorzugt werde

Quantum phases of atomic boson-fermion mixtures in optical lattices

The zero-temperature phase diagram of a binary mixture of bosonic and fermionic atoms in an one-dimensional optical lattice is studied in the framework of the Bose-Fermi-Hubbard model. By exact numerical solution of the associated eigenvalue problems, ground state observables and the response to an external phase twist are evaluated. The stiffnesses under phase variations provide measures for the boson superfluid fraction and the fermionic Drude weight. Several distinct quantum phases are identified as function of the strength of the repulsive boson-boson and the boson-fermion interaction. Besides the bosonic Mott-insulator phase, two other insulating phases are found, where both the bosonic superfluid fraction and the fermionic Drude weight vanish simultaneously. One of these double-insulator phases exhibits a crystalline diagonal long-range order, while the other is characterized by spatial separation of the two species.Comment: 4 pages, 3 figures, using REVTEX

Does preoperative analysis of intrahepatic venous anastomoses improve the surgeon's intraoperative decision making? Pilot data from a case report

<p>Abstract</p> <p>Background</p> <p>Three-dimensional (3D) visualization is thought to improve the anatomical understanding of clinicians, thus improving patient safety.</p> <p>Case presentation</p> <p>A 58-year-old male was admitted to our hospital in April 2007 with a suspected metastasis of a sigmoid cancer in the Couinaud segment (CS) 7. The anatomical situation of this patient was analyzed using both a CT scan and 3D images. The initial CT scan revealed that the proximal part of the middle hepatic vein was completely missing and the metastasis in the CS 7 was closely attached to the right hepatic vein. After analyzing additional 3D images, it became clear that due to the close proximity of metastasis and right hepatic vein, the resection of the right hepatic vein was inevitable. Based on this 3D analysis, it was decided to perform a right-sided hemihepatectomy. In this case report, 3D visualization resulted in a faster and clearer understanding of the unique anatomical situation in a patient with complicated liver anatomy than transversal CT images.</p> <p>Conclusion</p> <p>The here presented data shows for the first time 3D visualization of intravenous anastomoses in the human liver. The information offered by 3D visualization is not redundant but rather serves as a true source of additional information, indicating the potential benefit of 3D visualization in surgical operation planning.</p

Three-body interactions with cold polar molecules

We show that polar molecules driven by microwave fields give naturally rise to strong three-body interactions, while the two-particle interaction can be independently controlled and even switched off. The derivation of these effective interaction potentials is based on a microscopic understanding of the underlying molecular physics, and follows from a well controlled and systematic expansion into many-body interaction terms. For molecules trapped in an optical lattice, we show that these interaction potentials give rise to Hubbard models with strong nearest-neighbor two-body and three-body interaction. As an illustration, we study the one-dimensional Bose-Hubbard model with dominant three-body interaction and derive its phase diagram.Comment: 8 pages, 4 figure

To whom do the results of the multicenter, randomized, controlled INSECT trial (ISRCTN 24023541) apply? - assessment of external validity

A response to Seiler et al: Interrupted or continuous slowly absorbable sutures for closure of primary elective midline abdominal incisions: a multicenter randomized trial (INSECT: ISRCTN24023541). Ann Surg 2009, 249(4):576-582