Measurement of the Neutron-Neutron Scattering Length

The ¹S₀ neutron-neutron scattering length aₙₙ characterizes the two-neutron interaction at low energies and therefore is a fundamental quantity in many broad research fields such as nuclear structure physics. There were numerous attempts to determine the scattering length in the past decades, some of them with contradicting results, also including more recent ones. The precise and accurate measurement of aₙₙ still remains challenging and to this day, in contrast to the proton-proton scattering length, no direct measurement via n-n scattering is feasible. In this work, a new approach to measure aₙₙ is presented that makes use of relativistic radioactive ion beams created at high energies, in order to investigate n-n scattering at low energies. The experiment will be conducted at the "Radioactive Ion Beam Factory" of the research institute RIKEN in Japan and aims at the investigation of the free two-neutron system using the knockout reactions ⁶He(p,pα)2n and t(p,2p)2n. Furthermore, single-neutron events resulting from the d(p,2p)n reaction will serve for calibration and validation purposes. In the case of the ⁶He(p,pα)2n reaction, the n-n scattering length is accessible by comparison of the experimentally determined two-neutron relative-energy spectrum to calculations using the effective field theory for halo nuclei, called "Halo EFT". For the t(p,2p)2n reaction, the corresponding calculations will instead be based on pionless EFT. For the purpose of this experiment, the new high-resolution neutron detector HIME is currently developed and constructed at the "Institut für Kernphysik" in Darmstadt, Germany. A prototype of that detector has already been built at RIKEN. In this work, it was taken in operation and tested with electronics from "Gesellschaft für Schwerionenforschung" in Darmstadt. All reactions will take place in inverse kinematics with a beam energy of about 200 MeV/nucleon, resulting in two-neutron systems that move with relativistic velocity in the laboratory system. Thereby, a nearly constant neutron-detection efficiency in the relative-energy region of interest can be achieved. The measurements will be kinematically complete, which allows for a strong background suppression. In order to reach sufficient resolution, the relative-energy spectrum will be reconstructed by direct invariant-mass measurement, requiring coincident two-neutron detection. The analysis methods for the reconstruction of the primary interaction points in the neutron detector, which have been developed in this work, are tested and discussed with simulated data. Due to the limited resolution, efficiency and acceptance of the experimental setup, the measured relative-energy distribution cannot be compared directly to theoretical calculations. Different approaches of solving this issue are presented and discussed with simulated data as well

Shear bond strength of brackets to demineralize enamel after different pretreatment methods

Objective: To compare the influence of demineralized and variously pretreated demineralized enamel on the shear bond strength of orthodontic brackets. Materials and Methods: Sixty bovine enamel specimens were allocated to five groups (n  =  12). Specimens of group 1 were not demineralized and were not pretreated, but served as controls. The other specimens were demineralized to form artificial carious lesions. Samples from group 2 were only demineralized and were kept untreated in artificial saliva. The other samples were pretreated with highly concentrated fluoride preparations (group 3: Elmex Gelee, 1.23% F; group 4: Clinpro White Varnish, 2.23% F) or with an infiltrating resin (group 5: Icon). After respective pretreatments, brackets were adhesively fixed on all specimens with an adhesive system after etching with 35% phosphoric acid and application of a primer and bracket resin cement (Transbond XT). Bracket shear bond strength was evaluated with a universal testing machine. Statistical analysis was performed by one-way analysis of variance followed by a post-hoc Scheffé test. Results: Shear bond strength in control group 1 was statistically significantly greater compared with that in all other groups. Application of the infiltrating resin Icon (group 5) as pretreatment resulted in statistically significantly greater bond strength as compared with pretreatments with fluoride compounds (groups 3 and 4) and treatment provided without pretreatment (group 2). Groups 2, 3, and 4 did not significantly differ from each other. Conclusion: Pretreatment with the infiltrating resin is a beneficial approach to increasing the shear bond strength of brackets to demineralized enamel

Systematic evaluation of the features influencing the accuracy of third order measurements

The aims of this study were to evaluate the relationship of third order measurements on dental casts with those on lateral radiographs, and to identify those incisor features on radiographs which can best explain third order measurements on dental casts. Lateral cephalograms and corresponding dental casts were obtained from 39 untreated Caucasians (12 males, 27 females; mean age 19.5 years; standard deviation 3.7 years) with occlusal relationships considered to be ‘normal'. The upper (U1) and lower (L1) incisors were assessed with reference to the occlusal plane perpendicular which was established on the lateral radiographs, including third order angles (U1TR, L1TR) which were also derived from direct dental cast measurements (U1TA, L1TA). Both single regression and multiple linear regression analysis with stepwise variable selection were performed using third order measurements on casts as the dependent variable and crown axis (U1C, L1C), root axis (U1R, L1R), tip-apex connecting line (U1E, L1E), and radiographic third order measurements as independent variables. Single regression analysis indicated an overall difference of 0.02 degrees between radiographic third order inclination and cast assessment in the maxilla (mandible: −2.83 degrees). A change of 1 degree in radiographic third order inclination would produce a change of 0.65 degrees for U1TA and 0.86 degrees for L1TA assessments. Third order measurements on dental casts can best be explained by a linear combination of U1TR and U1E (maxilla) and of L1TR and L1C (mandible) measurements. This study demonstrates the functional enmeshment between two different third order assessments and the most common incisor features on lateral radiographs. Both methods of third order evaluation show sufficient reliability and are appropriate for routine orthodontic practic

Sarcomas of the extremities and the pelvis: comparing local recurrence after incisional and after core-needle biopsy

BACKGROUND The degree of contamination of healthy tissue with tumor cells during a biopsy in bone or soft tissue sarcomas is clearly dependant on the type of biopsy. Some studies have confirmed a clinically relevant contamination of the biopsy tract after incisional biopsies, as opposed to core-needle biopsies. The aim of our prospective study was to evaluate the risk of local recurrence depending on the biopsy type in extremity and pelvis sarcomas. METHODS We included 162 patients with a minimum follow-up of 6 months after wide resection of extremity sarcomas. All diagnostic and therapeutic procedures were performed at a single, dedicated sarcoma center. The excision of the biopsy tract after an incisional biopsy was performed as a standard with all tumor resections. All patients received their follow-up after the conclusion of therapy at our center by means of regional MRI studies and, at a minimum, CT of the thorax to rule out pulmonary metastatic disease. The aim of the study was the evaluation of the influence of the biopsy type and of several other clinical factors on the rate of local recurrence and on the time of local recurrence-free survival. RESULTS One hundred sixty-two patients with bone or soft tissue tumors of the extremities and the pelvis underwent either an incisional or a core-needle biopsy of their tumor, with 70 sarcomas (43.2%) being located in the bone. 84.6% of all biopsies were performed as core-needle biopsies. The median follow-up time was 55.6 months, and 22 patients (13.6%) developed a local recurrence after a median time of 22.4 months. There were no significant differences between incisional and core-needle biopsy regarding the risk of local recurrence in our subgroup analysis with differentiation by kind of tissue, grading of the sarcoma, and perioperative multimodal therapy. CONCLUSIONS In a large and homogenous cohort of extremity and pelvic sarcomas, we did not find significant differences between the groups of incisional and core-needle biopsy regarding the risk of local recurrence. The excision of the biopsy tract after incisional biopsy in the context of the definitive tumor resection seems to be the decisive factor for this result

Aneurysmal bone cyst: results of an off label treatment with Denosumab

Background The treatment of aneurysmal bone cysts (ABCs) has evolved and less invasive methods have been tried. Denosumab is a monoclonal antibody which inhibits osteoclasts. It has been shown to be effective in giant cell tumour of bone (GCT) of bone and hence promises some effect also in ABC. We report on 6 patients treated with Denosumab and compare our results to the cases already published. Methods Data of 6 patients with ABCs and patients whose treatment included Denosumab were retrospectively analyzed. Denosumab was used at a dose of 120 mg on days 1, 8, 15 and 29, and every 4 weeks thereafter. In some of these patients the dose was reduced at the end of the treatment. Clinical and radiological responses were evaluated. Results In 4 female and 2 male patients with a mean age of 17 years (range: 6–30 years) the lesions were located in the sacrum (2), in distal radius, distal femur, talus and pelvis. One of the sacral lesions healed after 12 months and has stayed stable for 3 years since. The second patient received 2 years of therapy with recalcification, but recurred 1 year later and is under renewed therapy. The pelvic lesion improved but recurred. This patient has a 13-years history of intermittent therapy including surgery, two pregnancies and remains in a stable situation. The lesion of the talus did not improve with Denosumab after surgery and was complicated by destruction of the ankle joint with osteoarthritis. Recurrent lesions of the distal femur and the distal radius, previously treated by curettage and bone grafting healed under Denosumab and have remained stable for 2 and 3 years, respectively. One case of severe hypercalcemia was observed in a 7-year old child 6 months after discontinuation of Denosumab. Conclusion Denosumab provides a treatment option for ABCs in anatomically critical locations. Adjuvant application might reduce the rate of local recurrence. In young patients, severe rebound hypercalcemia months after discontinuation of Denosumab may occur

Hematopoietic islands mimicking osteoblastic metastases within the axial skeleton

Background Hyperplasia of the hematopoietic bone marrow in the appendicular skeleton is common. In contrast, focal hematopoietic islands within the axial skeleton are a rare entity and can confuse with osteoblastic metastases. This study aimed to characterize typical MRI and CT findings of hematopoietic islands in distinction from osteoblastic metastases to help both radiologists and clinicians, on the one hand, not to overdiagnose this entity and, on the other hand, to decide on a reasonable work-up. Methods We retrospectively analyzed the imaging findings of 14 hematopoietic islands of the axial skeleton in ten patients (nine females, median age = 65.5 years [range, 49–74]) who received both MRI and CT at initial diagnosis between 2006 and 2020. CT-guided biopsy was performed in five cases to confirm the diagnosis, while the other five patients received long-term MRI follow-up (median follow-up = 28 months [range, 6–96 months]). Diffusion-weighted imaging was available in three, chemical shift imaging respectively 18 F- fluorodeoxyglucose PET/CT in two, and Technetium 99 m skeletal scintigraphy in one of the patients. Results All lesions were small (mean size = 1.72 cm 2 ) and showed moderate hypointense signals on T1- and T2-weighted MRI sequences. They appeared isointense to slightly hyperintense on STIR images and slightly enhanced after gadolinium administration. To differentiate this entity from osteoblastic metastases, CT provides important additional information, as hematopoietic islands do not show sclerosis. Conclusions Hematopoietic islands within the axial skeleton can occur and mimic osteoblastic metastases. However, the combination of MRI and CT allows for making the correct diagnosis in most cases

Neoadjuvant or adjuvant sirolimus for malignant metastatic or locally advanced perivascular epithelioid cell tumors: two case reports

Perivascular epithelioid cell tumors (PEComas) are very rare mesenchymal tumors, characterized by the presence of perivascular epithelioid cells. Despite their often benign nature, malignant variants with a locally aggressive growth pattern and even distant metastases are known. We describe two cases of malignant PEComas. The first patient had an extensive peritoneal spread and a history of multiple resections, and received the mechanistic target of rapamycin inhibitor sirolimus in a postoperative setting as maintenance therapy. The second patient presented with locally advanced disease in the iliac fossa and was treated with sirolimus in a neoadjuvant setting and achieved complete remission. Both patients have been under treatment for 18 and 52 months, respectively, and are currently in complete remission. These two cases indicate that mechanistic target of rapamycin inhibition for malignant PEComas could be a safe and successful treatment strategy in a neoadjuvant setting with an acceptable toxicity profile

Survival and prognostic factors in conventional G1 chondrosarcoma

Background Chondrosarcoma is the second most frequent malignant bone tumor. Grade I chondrosarcoma (syn.: atypical cartilaginous tumor) is classified as an intermediately and locally aggressive neoplasm and typically is treated less aggressively (i.e., by intralesional curettage). Does the data regarding local recurrence (LR) and metastatic disease justify this? Methods From 1982 to 2014, 37 consecutive patients with G1 chondrosarcoma had been resected or curetted. The margin was defined as R0 (wide resection) or R1 (marginal resection). All patients were followed for evidence of local recurrence or metastatic disease. Overall and recurrence-free survival were calculated, and various potentially prognostic factors were evaluated. Results In 23 patients (62%), the tumor was widely (R0) resected, whereas in 14 patients, (38%) the resection was marginal (R1). Overall survival was 97% after 5 years, 92% after 10 years, and 67% after 20 years. Five-year local recurrence-free survival was 96%. Ten-year local recurrence-free survival was 83%. Local recurrence-free survival showed a significant correlation to margin status but no correlation to location or age. None of the patients with local recurrence died during the follow-up. One patient had metastatic disease at initial presentation, and a further five patients developed metastatic disease during follow-up. Metastatic disease proofed to be a highly significant factor for survival but was not correlated to local recurrence. Conclusions There was no significant correlation between the outcome and the primary tumor location. Marginal resection was a risk factor for LR, but there was no significant difference in the overall survival in patients with or without LR. Metastatic disease (16%) was more common than expected from the literature and a significant predictor for poor overall survival

Diagnostic and prognostic impact of desmocollins in human lung cancer

Desmosomes are intercellular junctions that confer strong cell-cell adhesion. Two main members of desmosomal cadherins, desmogleins (DSGs) and desmocollins (DSCs), are involved in carcinogenesis. However, their role in human lung cancer remained elusive. The aims of this study were to analyse the expression of DSCs and to evaluate their clinical application in lung cancer

Loss of p16(INK4a) is associated with reduced patient survival in soft tissue tumours, and indicates a senescence barrier

Aims: p16(INK4a) is an important factor in carcinogenesis, and its expression is linked to oncogene-induced senescence. Very recently it was shown that upregulation and downregulation of p16 indicates a senescence barrier in the serrated route of colorectal cancer. However, in soft tissue sarcoma (STS), the senescence mechanism is still not understood. In this study, we analysed a well characterised cohort of STS for p16(INK4a) expression and correlated the results with clinicopathological parameters including survival. Methods: Tissue microarrays (TMA) of 183 soft tissue and bone tumours were analysed immunohistochemically. Furthermore, mRNA expression of p16(INK4a) was evaluated in four sarcoma cell lines, and a demethylation test was performed by treatment with 5-aza-2 \grq-deoxycytide. Results: On protein level, expression of p16(INK4a) was observed in undifferentiated pleomorphic sarcoma (UPS) in 69.1%, leiomyosarcoma in 85.7%, synovial sarcoma in 77.8%, liposarcoma in 88.9%, angiosarcoma in 60.9% and MPNST in 22.2%. Loss of p16(INK4a) was observed in high grade sarcomas and showed a significant correlation with reduced patient survival (p=0.032). On DNA level, one out of four sarcoma cell lines exhibited a methylated p16(INK4a) promoter analysed by methylation-specific PCR. p16(INK4a) mRNA and protein expression was restored after demethylation using 5-aza-2′-deoxycytide. Conclusions: Upregulation of p16(INK4a) might be associated with the induction of senescence and indicates a senescence barrier. Downregulation of p16(INK4a) is found in malignant progression, and is significantly correlated with reduced patient survival. Downregulation of p16(INK4a) may be explained by DNA-hypermethylation in sarcoma cells