J. Van Es

Yang-Yang thermodynamics on an atom chip

We investigate the behavior of a weakly interacting nearly one-dimensional trapped Bose gas at finite temperature. We perform in situ measurements of spatial density profiles and show that they are very well described by a model based on exact solutions obtained using the Yang-Yang thermodynamic formalism, in a regime where other, approximate theoretical approaches fail. We use Bose-gas focusing [I. Shvarchuck, Phys. Rev. Lett. 89, 270404 (2002)] to probe the axial momentum distribution of the gas and find good agreement with the in situ results.

Clot resolution after 3 weeks of anticoagulant treatment for pulmonary embolism: comparison of computed tomography and perfusion scintigraphy

Little is known about the natural history of clot resolution in the initial weeks of anticoagulant therapy in patients with acute pulmonary embolism (PE). Clot resolution of acute PE was assessed with either computed tomography pulmonary angiography scan (CT‐scan) or perfusion scintigraphy scan (Q‐scan) after 3 weeks of treatment.

How to prevent, treat, and overcome current clinical challenges of VTE

Summary.  Venous thromboembolism (VTE) is most commonly initially treated with low molecular weight heparin (LMWH), fondaparinux, or unfractionated heparin, in combination with vitamin‐K antagonists (VKA) for long‐term treatment. VKA have some drawbacks, however, which has led to the development of new anticoagulants. Most of these new drugs can be administered orally, and have been investigated in several phase III clinical trials. The benefits of these anticoagulants include their stable therapeutic effect, reduced interactions with other medication and food, and, therefore, the reduced need for regular monitoring. The duration of anticoagulant treatment for VTE is usually 3–12 months, but depends on the balance between the risks of recurrent thrombosis, major bleeding, and the patient’s preference. Clinical decision rules to assess the risk of recurrence to tailor the duration of anticoagulant treatment are being investigated. The beneficial aspects of novel anticoagulants may prolong the duration of treatment. VTE treatment should be adjusted in special patient groups, such as in cases of malignancy, renal failure, pregnancy, or obesity. In this review, the current and future aspects of the treatment of VTE are explored.

A simple decision rule including D-dimer to reduce the need for computed tomography scanning in patients with suspected pulmonary embolism.

An ‘unlikely’ clinical decision rule with a negative D‐dimer result safely excludes pulmonary embolism (PE) in 30% of presenting patients. We aimed to simplify this diagnostic approach and to increase its efficiency.

Variable D-dimer thresholds for diagnosis of clinically suspected acute pulmonary embolism

Computed tomography pulmonary angiography (CTPA) is frequently requested using diagnostic algorithms for suspected pulmonary embolism (PE). For suspected deep vein thrombosis, it was recently shown that doubling the D‐dimer threshold in patients with low pretest probability safely decreased the number of ultrasonograms. We evaluated the safety and efficiency of a similar strategy in patients with suspected PE.

Box traps on an atom chip for one-dimensional quantum gases

We present the implementation of tailored trapping potentials for ultracold gases on an atom chip. We realize highly elongated traps with box-like confinement along the long, axial direction combined with conventional harmonic confinement along the two radial directions. The design, fabrication and characterization of the atom chip and the box traps are described. We load ultracold ( 1 µK) clouds of 87Rb in a box trap, and demonstrate Bose-gas focusing as a means to characterize these atomic clouds in arbitrarily shaped potentials. Our results show that box-like axial potentials on atom chips are very promising for studies of one-dimensional quantum gases.

Longitudinal character of atom-chip-based rf-dressed potentials

We experimentally investigate the properties of radio-frequency-dressed potentials for Bose-Einstein condensates on atom chips. The three-dimensional potential forms a connected pair of parallel waveguides. We show that rf-dressed potentials are robust against the effect of small magnetic-field variations on the trap potential. Long-lived dipole oscillations of condensates induced in the rf-dressed potentials can be tuned to a remarkably low damping rate. We study a beam splitter for Bose-Einstein condensates and show that a propagating condensate can be dynamically split in two vertically separated parts and guided along two paths. The effect of gravity on the potential can be tuned and compensated for using a rf-field gradient.

The accuracy of D‐dimer testing in suspected pulmonary embolism varies with the Wells score

van Es J, Beenen LFM, Gerdes VEA, Middeldorp S, Douma RA, Bossuyt PMM. The accuracy of D‐dimer testing in suspected pulmonary embolism varies with the Wells score. J Thromb Haemost 2012; 10: 2630–2.

Is a normal computed tomography pulmonary angiography safe to rule out acute pulmonary embolism in patients with a likely clinical probability

A normal computed tomography pulmonary angiography (CTPA) remains a controversial criterion for ruling out acute pulmonary embolism (PE) in patients with a likely clinical probability. We set out to determine the risk of VTE and fatal PE after a normal CTPA in this patient category and compare these risk to those after a normal pulmonary angiogram of 1.7 % (95 %CI 1.0-2.7 %) and 0.3 % (95 %CI 0.02-0.7 %). A patient-level meta-analysis from 4 prospective diagnostic management studies that sequentially applied the Wells rule, D-dimer tests and CTPA to consecutive patients with clinically suspected acute PE. The primary outcome was the 3-month VTE incidence after a normal CTPA. A total of 6,148 patients were included with an overall PE prevalence of 24 %. The 3-month VTE incidence in all 4,421 patients in whom PE was excluded at baseline was 1.2 % (95 %CI 0.48-2.6) and the risk of fatal PE was 0.11 % (95 %CI 0.02-0.70). In patients with a likely clinical probability the 3-month incidences of VTE and fatal PE were 2.0 % (95 %CI 1.0-4.1 %) and 0.48 % (95 %CI 0.20-1.1 %) after a normal CTPA. The 3-month incidence of VTE was 6.3 % (95 %CI 3.0-12) in patients with a Wells rule >6 points. In conclusion, this study suggests that a normal CTPA may be considered as a valid diagnostic criterion to rule out PE in the majority of patients with a likely clinical probability, although the risk of VTE is higher in subgroups such as patients with a Wells rule >6 points for which a closer follow-up should be considered.

Performance of four clinical decision rules in patients with malignancy and suspected pulmonary embolism.

A substantial proportion (4–10%) of patients with suspected pulmonary embolism (PE) has a malignancy [1]. Conversely, patients with malignancy have a 4 to 7-fold increased risk of developing PE, particularly patients with metastatic disease, in whom the incidence varies from 4% to 20% [2]. PEworsens the prognosis in these vulnerable patients, because of the increased morbidity and mortality [3]. In the diagnostic strategy of PE, standardized clinical decision rules (CDRs) are commonly used to assess the probability of PE, with variables quantifying the likelihood of the diagnosis. Several CDRs have been derived and validated [4–7]. Themost commonCDR is theWells score, consisting of items obtained fromhistory, physical examination and a subjective item: a physician should judge if an alternative diagnosis is more likely than PE [8]. The Revised Geneva Score (RGS) is comparable, but lacks the subjective item and assigns different weight to the different variables [9]. In order to simplify the calculation of the scores, the Wells score and RGS have both been simplified: all items are now assigned with one point instead of the different weight per item in the original scores [4,5]. These four CDRs (Wells score, RGS, simplified Wells and simplified RGS) have recently been validated prospectively in patients with suspected PE and all showed a similar safety and clinical utility in excluding PE in combination with a negative D-dimer [10]. Interestingly, the subjective item: alternative diagnosis less likely than PE seemed predictive for PE in patients with malignancy [11]. Since the original and simplified Wells scores contain this item, these CDRs might exclude PE more often in patients with malignancy compared with the (simplified) RGS. However, because the item active malignancy is present in all CDRs, and D-dimer levels are often above the cut-off level in patients with malignancy, this diagnostic strategy is less specific for this high-risk category [11,12]. We assessed the performance of the four CDRs in excluding PE combined with a negative D-dimer test in patients with suspected PE and a malignancy. We performed a post-hoc analysis from a prospective multicentre cohort study of patients with clinically suspected PE, the design of which was described earlier [10]. Briefly, the dichotomized Wells score (cut-off value 4), simplified Wells score (cut-off value 1) and dichotomized RGS (cut-off value 5) and simplified RGS (cut-off value 2) were calculated and combinedwithhigh-sensitivityquantitativeD-dimer test.ACTscanwasperformed inpatientswitha likelyprobabilitybasedon at least one of the CDRs or if theD-dimer was elevated. In case of anunlikelyCDRwith all scores andanormalD-dimer result, PE was considered to be excluded. Patients were followed for 3 months. For the current analysis, we assessed patients who had a histological diagnosis of cancer, who were treated with chemoor radiation therapy within 6 months prior to study enrollment. We calculated the percentage of patients in whom PE could be excluded by an unlikely CDR and a negative Ddimer result (< 500 lg L). False-negative rates were calculated, defined as the number of patients in whom PE was diagnosed during additional diagnostic evaluation or during 3 months follow-up, despite anunlikelyCDRandanegativeDdimer level. Furthermore, we calculated the sensitivity, specificity and negative predictive value (NPV) of eachCDR.The 95% confidence intervals (CI) were calculated around the observed incidences.All analyseswere performedusingSPSSversion16.0 (SPSS, Chicago, IL, USA). Of807consecutivepatientswith suspectedPE,114 (14%)had a malignancy, of whom 34 patients (30%) were diagnosed with PE.Themeanagewas 60 years and58%were female (Table 1). First,we lookedat the resultsof theCDRswithout taking theDdimer test results into account. In patients with a malignancy, significantly more patients had an unlikely CDR using the original Wells score (58%, 95% CI 49–67) compared with the simplified Wells score (19%; 95% CI, 13–28) and both the original and simplified RGS (32%; 95% CI, 21–37). Nonetheless, the prevalence of PE in patients with an unlikely score did notdiffer significantlybetween the fourCDRs:Wells 18%(95% CI, 11–29); simplified Wells score 9% (95% CI, 2–28); RGS 24% (95% CI, 13–40); simplified RGS 22% (95% CI, 12–38). The sensitivity of the simplified Wells score (94%; 95% CI, 81–98) was higher compared with the other three CDRs: Wells score 65% (95% CI, 48–95%), RGS 74% (95% CI, 57–84%), Correspondence: Josien van Es, Department of Vascular Medicine, Academic Medical Centre, meibergdreef 9, Amsterdam 1011 AR, the Netherlands. Tel.: +31 20 5668675; fax: +31 20 5669343. E-mail: j.vanes@amc.uva.nl