Measurement of the α-Particle Monopole Transition Form Factor Challenges Theory: A Low-Energy Puzzle for Nuclear Forces?

We perform a systematic study of the α-particle excitation from its ground state 0_{1}^{+} to the 0_{2}^{+} resonance. The so-called monopole transition form factor is investigated via an electron scattering experiment in a broad Q^{2} range (from 0.5 to 5.0  fm^{-2}). The precision of the new data dramatically supersedes that of older sets of data, each covering only a portion of the Q^{2} range. The new data allow the determination of two coefficients in a low-momentum expansion, leading to a new puzzle. By confronting experiment to state-of-the-art theoretical calculations, we observe that modern nuclear forces, including those derived within chiral effective field theory that are well tested on a variety of observables, fail to reproduce the excitation of the α particle.

[Bilateral acetabulum fracture after suffering sport trauma]

This case study describes a 37-year-old male who suffered a bilateral transverse acetabulum fracture with a fracture of the posterior wall and a double-sided dorsal hip dislocation in combination with a left-sided femoral head fracture (Pipkin IV) while skiing in a "fun park". The accurate diagnosis and presurgical planning was made by means of a computed tomography (CT) scan and a subsequent 3D reconstruction. After a primarily executed shielded repositioning of the bilateral hip dislocationearly secondary and anatomical reconstruction of the double-sided acetabulum fracture was possible using the Kocher-Langenbeck approach. A consistent physiotherapy as well as rehabilitation finally led to a positive clinical result for the patient.

Gallstone prevalence and risk factors for gallstone disease in an urban population of children and adolescents

BACKGROUND

At present only a few sonography-based studies have assessed gallstone prevalence and associated risk factors in children and adolescents in randomly selected urban population samples. The aim of the present study was to analyze the prevalence of cholecystolithiasis and associated risk factors in children and adolescents.

METHODS

From a randomly selected urban population sample a total of 307 children and adolescents (157 girls, 150 boys; age 12 - 18 years, mean age 15.1 +/- 2.0 years) were studied using ultrasonography, standardized questionnaires and blood samples.

RESULTS

Three adolescents (one girl, two boys), corresponding to a prevalence of 1.0 %, showed gallstones. One 14-year-old girl and one 17-year-old boy were overweight using Cole's classification. A positive family history and female gender could not be confirmed as risk factors.

CONCLUSION

Obesity appears to be a risk factor in the development of gallstones in childhood and adolescence.

[Clinical experiences and dosage pattern in subcutaneous single-injection digital block technique]

100 patients with injuries to their fingers were treated using the subcutaneous digital block as described by Low et al.. Different dosages ranging from 2 to 3 millilitres of a local anesthetic were required to obtain appropriate anesthesia according to the location of injury. 108 finger injuries were treated, 18 thumb injuries, 90 finger injuries. The anesthetic was administered using a 0.55 x 25 mm needle and injected strictly subcutaneously into the flexor crease at the base of the finger or thumb. Injuries to the palmar aspect of the fingers were anesthetized using 2 ml of a local anesthetic (1% Lidocain), whereas 3 ml were needed for sufficient pain relief in case of injury to the dorsal aspect of the fingers. Injury to the thumb required a higher dosage (3 ml subcutaneously), and only offered sufficient pain relief for palmar injuries. In the case of dorsal injuries, we found that this technique was not sufficient in providing pain relief. Additionally, we performed a deep local nerve block (Oberst), if the patient still felt discomfort or pain. The severity or type of injury did not play a role according to our findings. The subcutaneous finger block as described by Low et al., therefore, is the method of choice treating injuries to the fingers and to the palmar aspect of the thumb, since it offers a decrease in the amount of anesthetic required and increases patient comfort.

Test of low-energy theorems for 1H(--> gamma, pi(0))(H)in the threshold hegion

The photon asymmetry in the reaction 1H(--> gamma,pi(0))(1)H close to threshold has been measured for the first time with the photon spectrometer TAPS using linearly polarized photons from the tagged-photon facility at the Mainz Microtron MAMI. The total and differential cross sections were also measured simultaneously with the photon asymmetry. This allowed determination of the S-wave and all three P-wave amplitudes. The values obtained at threshold are E(0+) = [-1.33+/-0.08(stat)+/-0.03(syst)] x 10(-3)/m(pi(+)), P(1) = [9.47 +/- 0.08(stat) +/- 0.29(syst)] x 10(-3)q/m(2)(pi(+)), P(2) = [-9.46 +/- 0.1(stat) +/- 0.29(syst)] x 10(-3)q/m(2)(pi(+)), and P(3) = [11.48 +/- 0.06(stat) +/- 0.35(syst)] x 10(-3)q/m(2)(pi(+)).

Measurement of the recoil polarization in the p(e-->, e'p-->)pi(0) reaction at the Delta(1232) resonance

The recoil proton polarization has been measured in the p(e-->,e'p-->)pi(0) reaction in parallel kinematics around W = 1232 MeV, Q2 = 0.121 (GeV/c)2, and epsilon = 0.718 using the polarized cw electron beam of the Mainz Microtron. All three proton polarization components, Px/P(e) = (-11.4+/-1.3+/-1.4)%, P(y) = (-43.1+/-1.3+/-2.2)%, and P(z)/P(e) = (56.2+/-1.5+/-2.6)%, could be measured simultaneously. The Coulomb quadrupole to magnetic dipole ratio, CMR = (-6.4+/-0.7(stat)+/-0.8(syst))%, was determined from Px in the framework of the Mainz Unitary Isobar Model. The consistency among the reduced polarizations and the extraction of the ratio of longitudinal-to-transverse response is discussed.