Angular momentum generation in nuclear fission.

When a heavy atomic nucleus splits (fission), the resulting fragments are observed to emerge spinning1; this phenomenon has been a mystery in nuclear physics for over 40 years2,3. The internal generation of typically six or seven units of angular momentum in each fragment is particularly puzzling for systems that start with zero, or almost zero, spin. There are currently no experimental observations that enable decisive discrimination between the many competing theories for the mechanism that generates the angular momentum4-12. Nevertheless, the consensus is that excitation of collective vibrational modes generates the intrinsic spin before the nucleus splits (pre-scission). Here we show that there is no significant correlation between the spins of the fragment partners, which leads us to conclude that angular momentum in fission is actually generated after the nucleus splits (post-scission). We present comprehensive data showing that the average spin is strongly mass-dependent, varying in saw-tooth distributions. We observe no notable dependence of fragment spin on the mass or charge of the partner nucleus, confirming the uncorrelated post-scission nature of the spin mechanism. To explain these observations, we propose that the collective motion of nucleons in the ruptured neck of the fissioning system generates two independent torques, analogous to the snapping of an elastic band. A parameterization based on occupation of angular momentum states according to statistical theory describes the full range of experimental data well. This insight into the role of spin in nuclear fission is not only important for the fundamental understanding and theoretical description of fission, but also has consequences for the γ-ray heating problem in nuclear reactors13,14, for the study of the structure of neutron-rich isotopes15,16, and for the synthesis and stability of super-heavy elements17,18.

Evolution of Octupole Deformation in Radium Nuclei from Coulomb Excitation of Radioactive

There is sparse direct experimental evidence that atomic nuclei can exhibit stable "pear" shapes arising from strong octupole correlations. In order to investigate the nature of octupole collectivity in radium isotopes, electric octupole (E3) matrix elements have been determined for transitions in ^{222,228}Ra nuclei using the method of sub-barrier, multistep Coulomb excitation. Beams of the radioactive radium isotopes were provided by the HIE-ISOLDE facility at CERN. The observed pattern of E3 matrix elements for different nuclear transitions is explained by describing ^{222}Ra as pear shaped with stable octupole deformation, while ^{228}Ra behaves like an octupole vibrator.

[Life-threatening subcutaneous emphysema after minor blow to the neck]. / Lebensbedrohliches Hautemphysem nach banalem Stoß gegen den Hals.

After a minor blow to the neck from the handlebars of a bike, a 5-year-old boy developed a massive subcutaneous emphysema with respiratory distress. Orotracheal intubation was performed. A computed tomography (CT) scan of the neck and thorax showed a pneumomediastinum and a bilateral pneumothorax. No injury to the large airways was identified. The patient was stabilized by insertion of chest tubes and controlled ventilation. The endoscopic examination of the trachea revealed a tear of the pars membranacea, which was successfully treated conservatively. The specific features of the injury and the airway management are discussed based on a review of the current literature.

Development of the cancer-related loneliness assessment tool: Using the findings of a qualitative analysis to generate questionnaire items.

The aim of this research was to develop a tool to identify and assess the qualities of cancer-related loneliness in adult cancer survivors who have completed treatment. In addition to reporting the development of the tool, we explicate the process of using the findings of a qualitative analysis to generate questionnaire items, as currently little guidance exists on this topic. The findings of our qualitative research exploring the experience of loneliness in adult cancer survivors who had completed treatment, together with the findings of our concept analysis of loneliness, were used to develop an assessment tool for cancer-related loneliness following treatment completion. Cognitive testing was undertaken to assess fidelity of comprehension and feasibility in administration. The Cancer-Related Loneliness Assessment Tool is a 10-item self-report questionnaire capturing the essential elements of cancer-related loneliness following treatment completion. Experts believed the questionnaire to be face-valid and usable in clinical practice, and preliminary cognitive testing indicated that the items generate the information intended and individuals have little trouble completing the tool. Following further development work, the tool could be employed to identify cancer-related loneliness following treatment completion. It could also aid with the development/adaptation and evaluation of person-centred interventions to address such loneliness.

Towards characterization of photo-excited electron transfer and catalysis in natural and artificial systems using XFELs.

The ultra-bright femtosecond X-ray pulses provided by X-ray Free Electron Lasers (XFELs) open capabilities for studying the structure and dynamics of a wide variety of biological and inorganic systems beyond what is possible at synchrotron sources. Although the structure and chemistry at the catalytic sites have been studied intensively in both biological and inorganic systems, a full understanding of the atomic-scale chemistry requires new approaches beyond the steady state X-ray crystallography and X-ray spectroscopy at cryogenic temperatures. Following the dynamic changes in the geometric and electronic structure at ambient conditions, while overcoming X-ray damage to the redox active catalytic center, is key for deriving reaction mechanisms. Such studies become possible by using the intense and ultra-short femtosecond X-ray pulses from an XFEL, where sample is probed before it is damaged. We have developed methodology for simultaneously collecting X-ray diffraction data and X-ray emission spectra, using an energy dispersive spectrometer, at ambient conditions, and used this approach to study the room temperature structure and intermediate states of the photosynthetic water oxidizing metallo-protein, photosystem II. Moreover, we have also used this setup to simultaneously collect the X-ray emission spectra from multiple metals to follow the ultrafast dynamics of light-induced charge transfer between multiple metal sites. A Mn-Ti containing system was studied at an XFEL to demonstrate the efficacy and potential of this method.

[Spontaneous bone regeneration following ceratocystic odontogenic tumor]. / Spontane Knochenregeneration nach keratozystischem odontogenem Tumor.

A patient presents with a keratocystic odontogenic tumour of the left maxillary sinus. In computed tomography scans, extensive pressure-induced osseous atrophy of the sinus walls is detected. Endoscopic cystectomy of the tumour was performed, with subsequent clinical follow-up. A second computed tomography scan revealed almost complete regeneration of the sinus walls. Where spontaneous regeneration of osseous structures is possible, restraint should be exercised when assessing indications for bony reconstruction during initial conservative surgery such as enucleation.

(97)(37)Rb(60): The Cornerstone of the Region of Deformation around A ∼ 100 [corrected].

Excited states of the neutron-rich nuclei (97,99)Rb were populated for the first time using the multistep Coulomb excitation of radioactive beams. Comparisons of the results with particle-rotor model calculations provide clear identification for the ground-state rotational band of (97)Rb as being built on the πg(9/2) [431] 3/2(+) Nilsson-model configuration. The ground-state excitation spectra of the Rb isotopes show a marked distinction between single-particle-like structures below N=60 and rotational bands above. The present study defines the limits of the deformed region around A∼100 and indicates that the deformation of (97)Rb is essentially the same as that observed well inside the deformed region. It further highlights the power of the Coulomb-excitation technique for obtaining spectroscopic information far from stability. The (99)Rb case demonstrates the challenges of studies with very short-lived postaccelerated radioactive beams.

Yrast 6⁺ seniority isomers of (136,138)Sn.

Delayed γ-ray cascades, originating from the decay of (6⁺) isomeric states, in the very neutron-rich, semimagic isotopes (136,138)Sn have been observed following the projectile fission of a ²³8U beam at RIBF, RIKEN. The wave functions of these isomeric states are proposed to be predominantly a fully aligned pair of f(7/2) neutrons. Shell-model calculations, performed using a realistic effective interaction, reproduce well the energies of the excited states of these nuclei and the measured transition rates, with the exception of the B(E2;6⁺→4⁺) rate of ¹³6Sn, which deviates from a simple seniority scheme. Empirically reducing the νf(7/2)(2) orbit matrix elements produces a 41⁺ state with almost equal seniority 2 and 4 components, correctly reproducing the experimental B(E2;6⁺→4⁺) rate of ¹³6Sn. These data provide a key benchmark for shell-model interactions far from stability.

1p3/2 proton-hole state in 132Sn and the shell structure along N = 82.

A low-lying state in 131In82, the one-proton hole nucleus with respect to double magic 132Sn, was observed by its γ decay to the Iπ=1/2- ß-emitting isomer. We identify the new state at an excitation energy of Ex=1353 keV, which was populated both in the ß decay of 131Cd83 and after ß-delayed neutron emission from 132Cd84, as the previously unknown πp3/2 single-hole state with respect to the 132Sn core. Exploiting this crucial new experimental information, shell-model calculations were performed to study the structure of experimentally inaccessible N=82 isotones below 132Sn. The results evidence a surprising absence of proton subshell closures along the chain of N=82 isotones. The consequences of this finding for the evolution of the N=82 shell gap along the r-process path are discussed.

[Current practice of tumour endoscopy in German ENT-clinics]. / Praxis der Tumorendoskopie an deutschen HNO-Kliniken.

BACKGROUND: Second primary carcinomas (SPC) essentially influence therapy and the outcome in head and neck cancer. This study presents the current status of tumour endoscopy in German ENT-clinics. MATERIAL AND METHODS: A standardised questionnaire regarding indication, time of event, examined anatomical region and technique of tumour endoscopy was compiled, sent to all German ENT-clinics (n=159) and subsequently analysed. RESULTS: In 94-100% of the clinics, tumour endoscopy is being conducted when primary carcinoma lies within oral cavity, pharynx, larynx or is a CUP-syndrome. In 80%, 2-stage surgical procedure is preferred. Nasal cavity and tracheobronchial system (47%, 74%) are often not included in the examination. When primary cancer is seen, in 7% of the clinics a standardised biopsy of unsuspicious anatomic areas is conducted. In CUP-syndrome, unsuspicious surfaces within the pharynx do not undergo routine biopsy in 10-20% of the clinics. In tracheobronchoscopy (63.0%) and esophagoscopy (93.3%) rigid scopes are mainly used. 65% of the clinics conduct endoscopy as follow-up care. CONCLUSION: Practice of tumour endoscopy in German ENT-clinics is widespread but does not follow standardised mechanisms. Current international literature shows that there is no common consensus on value and techniques of tumour endoscopy, however, due to highly developed radiological diagnostics, risks of rigid endoscopies and unknown incidence of second primary tumours it is discussed more and more negative. To establish future guidelines, controlled studies or analysis of large populations seem to be necessary.

Evidence for a smooth onset of deformation in the neutron-rich Kr isotopes.

The neutron-rich nuclei 94,96Kr were studied via projectile Coulomb excitation at the REX-ISOLDE facility at CERN. Level energies of the first excited 2(+) states and their absolute E2 transition strengths to the ground state are determined and discussed in the context of the E(2(1)(+)) and B(E2;2(1)(+)→0(1)(+)) systematics of the krypton chain. Contrary to previously published results no sudden onset of deformation is observed. This experimental result is supported by a new proton-neutron interacting boson model calculation based on the constrained Hartree-Fock-Bogoliubov approach using the microscopic Gogny-D1M energy density functional.

Transition metal phthalocyanines: insight into the electronic structure from soft x-ray spectroscopy.

Transition metal phthalocyanines (MPc's) are an interesting class of material, and their magnetic and electronic properties are determined by the orbital occupation of the transition metal 3d orbitals incorporated in the molecules center. Thus, the ground state configuration of the transition metal center is very important for a complete understanding of these materials. We present experimental data taken using x-ray absorption and x-ray photoemission spectroscopy together with a theoretical interpretation of MPc series with M=Zn, Cu, Ni, Co, Fe, and Mn. The combination of these methods allows us to narrow down possible dominating ground state configurations and shed a brighter light on the electronic structure of these complexes.

[Significance of frozen section diagnosis for the management of laryngeal tumors]. / Bedeutung der Schnellschnittdiagnostik für das Management laryngealer Tumoren.

The frozen section procedure for immediate intraoperative pathological diagnosis represents a pivotal method in tumor diagnosis. In laryngeal tumors the most frequent indication for the use of this method is the documentation of the residual tumor status, while intraoperative consultation with the purpose of primary tumor diagnosis is less common. The specimen management employed in each case should be chosen depending on the clinical question: while the collection of a maximum amount of tissue is advisable for the determination of the residual tumor status, sparing a portion of the remaining tissue for possible future examinations is advisable in the case of primary tumor diagnosis. Moreover, intraoperative frozen section diagnosis with no immediate consequences should be avoided.

[Intraductal application of Levovist® in salivary glands of animals]. / Intraduktale Applikation von Levovist® in Speicheldrüsenausführungsgänge am Tiermodell.

BACKGROUND: Several methods are well established for the imaging of salivary glands. Excluding the invasive method sialendoscopy all other methods show the salivary duct system inadequately. The aim of this study is to demonstrate a method to visualize the salivary duct system by B-mode ultrasound. MATERIAL AND METHODS: In 10 parotid glands of common pig cadavers the ultrasound contrast agent Levovist (®), which is galactose stabilized by palmitic acid was applied into the main salivary ducts while simultaneously performing a transcutaneous B-mode ultrasound. RESULTS: In all cadavers a visualization of the salivary duct system could be achieved by the application of Levovist (®) because of contrast enhancement. This effect arises as a result of an increased reflection of ultrasound waves on the surface of the microbubbles contained in the contrast agent. CONCLUSION: A reproducible visualization of the salivary duct system with B-mode ultrasound is possible by an intraductal application of an ultrasound contrast agent. In future this could be established as a reliable and fast method for imaging of the salivary ducts without ionizing radiation for the patient.

[Sialendoscopy--learning curve and nation-wide survey in German ENT-departments]. / Sialendoskopie--Lernkurve und Verbreitung in deutschen HNO-Kliniken.

BACKGROUND: Sialendoscopy is an established, minimal-invasive technique to diagnose and treat obstructive diseases of major salivary glands. Knowledge on learning curve and distribution in Germany is limited. MATERIAL UND METHODS: An 11 item questionnaire on Sialendoscopy was sent to all 159 German ent-hospitals. To determine the learning curve, all patients that underwent sialendoscopy during a 1-year-period after invention of sialendoscopy in our department were prospectively followed and evaluated. RESULTS: Sialendoscopy is currently performed in a minority (24%) of ent-departments in Germany. Denial was justified by technical problems, a lack of cost-benefit and small number of patients in descending order. A significant reduction of intervention time (61.0 ± 32.7 min to 43.2 ± 33.6 min, p=0.013) and less frequent aborted operations were noted after comparison of the first vs. the second half amount of interventions as indicators of a learning curve. Complications were not found to be significantly raised in the first half of interventions. CONCLUSION: The fact that sialendoscopy is provided in only a minority of ent-departments will in the future most likely be overcome by technical improvements. A learning curve has to be anticipated.

5f covalency from x-ray resonant Raman spectroscopy.

X-ray resonant Raman spectroscopy (XRRS), a variant of resonant inelastic x-ray scattering, has been used to investigate the two prototype systems, UF4and UO2. Both are U5f2and each is an example of 5f localized, ionic behavior and 5f localized, covalent behavior, respectively. From the M5XRRS measurements, the 5f band gap in each can be directly determined and, moreover, a clear and powerful sensitivity to 5f covalency emerges.

Discovery of the shape coexisting 0+ state in 32 Mg by a two neutron transfer reaction.

The "island of inversion" nucleus 32 Mg has been studied by a (t, p) two neutron transfer reaction in inverse kinematics at REX-ISOLDE. The shape coexistent excited 0+ state in 32 Mg has been identified by the characteristic angular distribution of the protons of the Δ L=0 transfer. The excitation energy of 1058 keV is much lower than predicted by any theoretical model. The low γ-ray intensity observed for the decay of this 0+ state indicates a lifetime of more than 10 ns. Deduced spectroscopic amplitudes are compared with occupation numbers from shell-model calculations.