Triangle Singularity as the Origin of the a_{1}(1420).

The COMPASS Collaboration experiment recently discovered a new isovector resonancelike signal with axial-vector quantum numbers, the a_{1}(1420), decaying to f_{0}(980)π. With a mass too close to and a width smaller than the axial-vector ground state a_{1}(1260), it was immediately interpreted as a new light exotic meson, similar to the X, Y, Z states in the hidden-charm sector. We show that a resonancelike signal fully matching the experimental data is produced by the decay of the a_{1}(1260) resonance into K^{*}(→Kπ)K[over ¯] and subsequent rescattering through a triangle singularity into the coupled f_{0}(980)π channel. The amplitude for this process is calculated using a new approach based on dispersion relations. The triangle-singularity model is fitted to the partial-wave data of the COMPASS experiment. Despite having fewer parameters, this fit shows a slightly better quality than the one using a resonance hypothesis and thus eliminates the need for an additional resonance in order to describe the data. We thereby demonstrate for the first time in the light-meson sector that a resonancelike structure in the experimental data can be described by rescattering through a triangle singularity, providing evidence for a genuine three-body effect.

Beam-Recoil Polarization Measurement of π

The helicity-dependent recoil proton polarizations P_{x}^{'} and P_{z}^{'} as well as the helicity-independent component P_{y} have been measured in the p(e[over →],e^{'}p[over →])π^{0} reaction at four-momentum transfer Q^{2}≃0.1 GeV^{2}, center-of-mass proton emission angle θ_{p}^{*}≃90°, and invariant mass W≃1440 MeV. This first precise measurement of double-polarization observables in the energy domain of the Roper resonance P_{11}(1440) by exploiting recoil polarimetry has allowed for the extraction of its scalar electroexcitation amplitude at an unprecedentedly low value of Q^{2}, establishing a powerful instrument for probing the interplay of quark and meson degrees of freedom in the nucleon.

The impact and recovery of asteroid 2008 TC(3).

In the absence of a firm link between individual meteorites and their asteroidal parent bodies, asteroids are typically characterized only by their light reflection properties, and grouped accordingly into classes. On 6 October 2008, a small asteroid was discovered with a flat reflectance spectrum in the 554-995 nm wavelength range, and designated 2008 TC(3) (refs 4-6). It subsequently hit the Earth. Because it exploded at 37 km altitude, no macroscopic fragments were expected to survive. Here we report that a dedicated search along the approach trajectory recovered 47 meteorites, fragments of a single body named Almahata Sitta, with a total mass of 3.95 kg. Analysis of one of these meteorites shows it to be an achondrite, a polymict ureilite, anomalous in its class: ultra-fine-grained and porous, with large carbonaceous grains. The combined asteroid and meteorite reflectance spectra identify the asteroid as F class, now firmly linked to dark carbon-rich anomalous ureilites, a material so fragile it was not previously represented in meteorite collections.

High-precision determination of the electric and magnetic form factors of the proton.

New precise results of a measurement of the elastic electron-proton scattering cross section performed at the Mainz Microtron MAMI are presented. About 1400 cross sections were measured with negative four-momentum transfers squared up to Q² = 1 (GeV/c)² with statistical errors below 0.2%. The electric and magnetic form factors of the proton were extracted by fits of a large variety of form factor models directly to the cross sections. The form factors show some features at the scale of the pion cloud. The charge and magnetic radii are determined to be ½ = 0.879(5)stat(4)syst(2)model(4)group fm and ½ = 0.777(13)stat(9)syst(5)model(2)group fm.

Bone densitometry and histomorphometry in patients with hairy cell leukemia.

Tumor necrosis factor alpha, the cytokine that participates in the autocrine growth control of hairy cell leukemia has strong bone resorptive properties. This prompted us to look for bone involvement in HCL. Bone mineral density (BMD) was not decreased in 14 HCL patients who did not have radiographic evidence of bone destruction. Osteopenia was found in only two HCL patients with skeletal complications of the disease and bone pain preceded diagnosis in both cases. Lymphomatous infiltration of the vertebral bodies T 12/L1 was confirmed histologically in the female patient while bilateral necrosis of the femoral head preceded the diagnosis of HCL in the male patient. Histomorphometry of bone biopsy samples was performed in another 12, previously untreated male HCL patients. Trabecular bone volume was found to be reduced in 11, greatly reduced in 5 of them, while osteosclerosis was found in only one patient. The increase of trabecular bone pattern factor, a new parameter for simple quantification of trabecular interconnection indicated a poorly connected trabecular lattice in eight of these 12 patients.

Flushable stent-system for internal drainage in occlusive jaundice.

The effectiveness of biliary stents may be reduced as a result of obstruction by tumor material, bile salts or detritus. To circumvent this problem we developed a prosthesis system, which allows flushing and repetitive radiological control via a subcutaneous port. Prostheses were implanted in 26 patients presenting with inoperable occlusive lesions of the bile duct. Patency was regularly monitored by checking the bilirubin and alkaline phosphatase levels and using port-cholangiography. Catheter function was easily maintained in 92% of the patients and ended upon malignancy related death. In case of dysfunction, drainage could generally be restored with intensive flushing. This new flushable stent-system was easily implantable, could be exchanged without renewed percutaneous transhepatic puncture and allowed flushing, external drainage, bile probes for bacteriological examinations and follow up cholangiography via the subcutaneous placed port.

Radiographic aspects in transcatheter contact dissolution of calcified gallbladder concrements.

The present study on 10 patients reports upon an attempt to perform percutaneous contact dissolution of partially calcified gallbladder concrements. These gallstones, which exhibited structural calcifications on CT scans, required time-consuming complex dissolution procedures with transcatheter administration of methyl tert-butyl ether (MTBE) and ethylene diamine tetraacetic acid (EDTA). Insertion of the catheter system (5 F) was performed via a percutaneous transhepatic route. Catheter placement was maintained for a maximum of 4 days. Complete lysis was achieved in seven of the ten cases. In six patients, significant regional or disseminated chemically induced cholecystitis and pericholecystitis could be observed on CT examination. However, on follow-up CT examinations, these changes proved to be completely reversible. It has been demonstrated that tolerance of the gallbladder wall and adjacent tissue layer against the lytic media employed is rather limited and that meticulous controlling of the morphological reaction can be helpful in minimizing complications.

[Bone lesions in chronic pancreatitis]. / Knöcherne Läsionen bei chronischer Pankreatitis.

Case reports of 4 patients with combined pancreatic and bone marrow disease are presented. 3 of them were alcoholics and suffered from chronic pancreatitis and bacterial osteomyelitis, one showed lipolytic lesions of the bone marrow following an acute exacerbation of a chronic lithogenic pancreatitis. X-ray examination of the left hand, both feet and tibiae showed evidence of multifocal small osteolytic defects accompanied by periosteal reaction in the case of lipolytic bone lesions. The appearance resembles that of an osteomyelitis, however, lacking the extensive destruction and sclerotic reaction. These bone lesions were associated with neurological symptoms and subcutaneous nodules. In one patient histological investigation of the bone lesions showed osteomyelitic and lipolytic changes so that there might be an association between both diseases.

[Radiological diagnosis of intraosseous lipoma]. / Aspekte der radiologischen Diagnostik des intraossären Lipoms.

Intraosseous lipomas exhibit a very characteristic radiological appearance. Diagnosis can be derived exclusively from x-ray examinations if a sharply defined cystic lesion with dense central sclerosis and fat-equivalent CT values is detected. When the latter criterion is not markedly pronounced the occurrence of a lipoma-derived, e.g. myxomatous, process can be discussed.

[Modification of the imaging quality of the small intestine by using methylcellulose of different classes of viscosity]. / Beeinflussung der Darstellungsqualität des Dünndarms durch Verwendung von Hydroxymethylzellulosen unterschiedlicher Viskositätsklassen.

In certain diseases originating from the small intestine the peroral application of contrast medium can complete with enteroclysis. The use of methylcellulose MH 1000 proved to be a good compromise between viscosity ans stability of mucosal coating. It allowed good image quality in all segments of the small bowel particularly in the distal ileum. Therefore, this method is clearly indicated in Crohn's disease. Good results were also obtained in delineating tumours, radiation enteritis and ischaemic enteritis. With few patients exhibiting reduced small bowel mobility and/or who are incapable of drinking adequate volumes of contrast medium the results of the oral method are rather unfavourable.

[Angiographic diagnosis in giant cell arteritis of the arm arteries]. / Angiographische Diagnose bei Riesenzellarteriitis der Armarterien.

Three women of 66, 68 and 69 years of age presented with chronic arm claudication caused by giant cell arteritic stenoses and occlusions of their arm arteries. In the early stage of the disease, arteriography revealed smooth or undulatory long-segment narrowings. Subsequently, spindle-shaped filiform stenoses developed. They were unilateral in one patient, bilateral-symmetric in another and like a string of beads in the third. In the end, untreated arteritis resulted in smoothly tapered occlusions of the diseased vessels. In patients with symptoms and signs suggestive of giant cell arteritis, typical arteriographic findings may confirm the diagnosis even if histopathological proof is lacking.

[Scintigraphy using erythrocytes labeled in vivo with 99mTc. Detection of an intestinal hemorrhage following a duodenum-preserving resection of the pancreas head]. / Die Szintigraphie mit 99mTc-in-vivo-markierten Erythrozyten. Nachweis einer intestinalen Blutung nach duodenumerhaltender pankreaskopfresektion.

Following resection of the head of the pancreas while preserving the duodenum a gastrointestinal haemorrhage was localised by red blood cells labeled in vivo with technetium-99m. The previously performed endoscopy and angiography were normal. The haemorrhage in the region of the pancreatico-jejunal anastomosis was confirmed intraoperatively. If intermittent bleedings are suspected, scintigraphy should be performed as a routine measure besides endoscopy and angiography.

[Biliary obstruction: MR-cholangiography with a rapid gradient-echo sequence (2D CE-Fast)]. / Biliäre Obstruktion: MR-Cholangiographie mit einer schnellen Gradientenecho-Sequenz (2D CE-Fast).

Magnetic resonance (MR) was used to delineate the biliary tree in patients with obstructive jaundice originating from various types of malignant or benign processes at different locations. With the aid of a rapid sequential gradient-echo acquisition (CE-Fast) and 3D post-processing, heavily T2-weighted images could be obtained to identify the site of obstruction in ten out of eleven patients. Slices were acquired during breath-holding periods of about 12 sec with a total examination time of 10-15 min. The three-dimensional display reliably demonstrated the dilated bile ducts in pre-stenotic areas whereas in the majority of cases post-stenotic ductal segments could not be visualised.

[Transvenous DSA of the extracranial cerebral arteries. Causes of reduced image quality based on a critical analysis of 1000 patients]. / Transvenöse DSA der extrakraniellen Hirnarterien. Ursachen einer reduzierten Bildqualität nach kritischer Analyse an 1000 Patienten.

In this study images of 1000 patients examined via transvenous DSA were analysed and the image quality scrutinised for each vascular region while determining the causes of image quality reduction. The results show that the diagnostic image quality was 98% (excellent/good 79%, fair: 19%) for a. carotis communis, 94% (69 and 25%, respectively) for carotid bifurcation, 84% (54%, 30%) for distal int. carotid arteries, 91% (65%, 26%) for vertebral arteries and 74% (45%, 29%) for basilar artery. Reasons for image quality reduction were artifacts due to movements by the patients, and were also due to vascular superposition. Reduced left ventricular function resulting in prolonged circulation time and dilution of contrast material was frequently combined with an advanced age of the patients (greater than 75 years). Our studies suggest that transvenous DSA is not useful in patients with significantly reduced cardiac output who do not cooperate properly and are of advanced age. It may, therefore, be omitted to avoid unnecessary stress and high cost. In such cases intraarterial DSA or conventional angiography is indicated.

[Intra-arterial DSA of the hand arteries in the diagnosis of inflammatory connective tissue diseases]. / Die intraarterielle DSA der Handarterien in der Diagnostik entzündlicher Bindegewebserkrankungen.

Seventy-five patients with suspected rheumatic diseases underwent intraarterial DSA of the hand arteries. In 81% of the patients we were able to establish the diagnosis of vasculitis according to angiographic criteria. Neither clinical nor chemical or immunological features allowed the diagnosis of an inflammatory disease of joint and perivascular tissue at this time. However, histological examination and immunofluorescence microscopy confirmed the angiographic findings and showed signs of an immune complex vasculitis. A strong predictor for an abnormal angiogram of the hand arteries is the presence of Sicca's and Raynaud's Syndrome in addition to rheumatoid joint pain.

[Venous occlusions distant to the shunt as malfunction factors during hemodialysis]. / Shuntferne venöse Okklusionen als Störungsfaktoren bei der Hämodialyse.

On 78 patients with dysfunction of haemodialysis vascular access (predominantly poor flow) systematic radiographic evaluation was performed. In all cases arteriography was carried out, followed by venous angiography in patients exhibiting occlusion of the arteriovenous fistula or the graft, respectively. In 11 cases (14%) occlusion or significant stenosis of far proximal venous vessels (axillary and/or subclavian vein) could be detected. It is suggested that consecutive deterioration of central venous runoff may induce or aggravate malfunctioning of the shunt and, moreover, may contribute to recurrent thrombosis of arteriovenous fistulae or grafts.

[Magnetic resonance tomographic imaging of pulsatile CSF movement in communicating hydrocephalus before and after shunt placement]. / Magnetresonanztomographische Darstellung der Liquorpulsbewegung bei Hydrozephalus communicans vor und nach Shuntanlage.

16 patients with hydrocephalus communicans and 5 healthy volunteers were examined to demonstrate the pattern of the pulsatile CSF flow. After implantation of a CSF shunt system the same patients were examined again to show the influence of the shunt on the CSF pulsations. We used a flow-sensitised, cardiac-gated 2D FLASH sequence and analysed the phase and magnitude images. It could be shown that most patients (n = 12) had a hyperdynamic pulsatile flow preoperatively. After shunt implantation the pulsatile CSF motion and the clinical symptoms were improved in 8 of these patients. MRI of pulsatile CSF flow movement seems to be a helpful noninvasive tool to estimate the prognosis of a shunt implantation in patients with hydrocephalus communicans.

[Sonographic findings in lateral ligament lesions of the upper ankle joint following conservative and operative therapy]. / Sonographische Befunde bei lateralen Bandläsionen des oberen Sprunggelenkes nach konservativer und operativer Therapie.

72 patients with injury of the ankle joint were examined with ultrasound after therapy. Sonographic findings were assessed by plain x-ray films and stress views. In 39 patients an injury of the lateral ligament was treated by surgery and in 33 patients without surgery. 40 patients showed a scar of the lateral ligaments. Patients treated without surgery and showing a scar in ultrasound demonstrated a smaller tilt of the talus in stress views than patients without scars. Measurement of stability was not possible. In conclusion, sonography is a valuable tool in examining the ankle joint after therapy. With regard to stability, stress films cannot be replaced by sonography.

[Clinical potentialities and limitations of two- and three-dimensional time-of-flight MR angiography in the diagnosis of carotid stenosis]. / Klinische Möglichkeiten und Grenzen der zwei- und dreidimensionalen Time-of-Flight-MR-Angiographie in der Diagnostik der Karotisstenose.

For diagnosing a carotid artery stenosis, 26 patients underwent MR angiography. A spin echo (SE) sequence with presaturation on which the flowing blood appears with low signal intensity was applied, as well as a two- and three-dimensional gradient echo (GRE) sequence with flow compensation, showing blood flow with high signal intensity. Subsequently, projection angiograms were made from the MR images with a maximum intensity projection algorithm. Degree, length and localisation of a carotid artery stenosis were reviewed. To find out the clinical usability, the results of the MR angiograms were compared subsequently with the findings of intravenous digital subtraction angiography (i.v. DSA). In comparison with DSA a correlation in the degree of stenosis was noticed in 42 out of 48 SE-, in 39 out of 52 2-D GRE and in 41 out of 48 3-D GRE sequence angiograms. The length of 34 moderate and severe stenoses, demonstrated by DSA, was overestimated 5 times with the SE-sequence, 9 times with the 3-D and 23 times with the 2-D GRE sequence. MR angiography with a 3-D GRE sequence is suitable for screening for carotid artery stenosis. In cases of severe stenosis an SE sequence should be performed for more precise delineation of the stenotic lesion.

[Magnetic resonance tomography of the liver with TurboFLASH and segmented acquisition. Fast imaging with flexible image contrast]. / Magnetresonanztomographie der Leber mit TurboFLASH und segmentierter Akquisition. Schnelle Bildgebung mit variablem Bildkontrast.

The value of a fast imaging sequence in diagnosing focal liver lesions was assessed in 43 patients. The sequence (TurboFLASH with segmented acquisition) allows the acquisition of T1- and T2-weighted images within a breath-hold interval. Lesion-liver contrast was compared with T2-weighted spin-echo, T1-weighted gradient-echo, and single shot TurboFLASH sequences. All lesions that were seen with the latter sequences were also visible on the segmented TurboFLASH images. Contrast on the segmented TurboFLASH images was similar to that of T2-weighted spin-echo sequences and superior to T1-weighted gradient-echo sequences. Signal of fat could be nulled at an inversion time of 10 ms, signal from liver tissue could be nulled at an inversion time of 300 ms. By minimising the liver signal, the lesions could be "highlighted". This was not possible with the other imaging sequences. The segmented TurboFLASH technique allows breath-hold imaging of the liver with arbitrary image contrast. The lesion-liver contrast is comparable to time-consuming T2-weighted spin-echo sequences.