This Letter details a measurement of the ionization yield (Q(y)) of 6.7 keV(40)Ar atoms stopping in a liquid argon detector. The Q(y) of 3.6-6.3 detected e(-)/keV, for applied electric fields in the ...range 240-2130 V/cm, is encouraging for the use of this detector medium to search for the signals from hypothetical dark matter particle interactions and from coherent elastic neutrino-nucleus scattering. A significant dependence of Q(y) on the applied electric field is observed and explained in the context of ion recombination.
After the initial correction of congenital talipes equinovarus (CTEV) using the Ponseti method, a subsequent dynamic deformity is often managed by transfer of the tendon of tibialis anterior (TATT) ...to the lateral cuneiform. Many surgeons believe the lateral cuneiform should be ossified before surgery is undertaken. This study quantifies the ossification process of the lateral cuneiform in children with CTEV between one and three years of age.
The length, width and height of the lateral cuneiform were measured in 43 consecutive patients with unilateral CTEV who had been treated using the Ponseti method. Measurements were taken by two independent observers on standardised anteroposterior and lateral radiographs of both feet taken at one, two and three years of age.
All dimensions of the lateral cuneiform on the affected side increased annually but remained smaller than the corresponding dimensions of the unaffected foot (p < 0.01). The lateral cuneiform resembled a 9 mm cube at two years and an 11 mm cube at three years.
At one and two years, the ossification centre of the lateral cuneiform may not be large enough to accommodate a drill hole for tendon transfer. However, by three years, it has undergone sufficient ossification to do so. Cite this article:
2017;99-B:1109-14.
Background
Idiopathic clubfoot correction is commonly performed using the Ponseti method and is widely reported to provide reliable results. However, a relapsed deformity may occur and often is ...treated in children older than 2.5 years with repeat casting, followed by an anterior tibial tendon transfer. Several techniques have been described, including a whole tendon transfer using a two-incision technique or a three-incision technique, and a split transfer, but little is known regarding the biomechanical effects of these transfers on forefoot and hindfoot motion.
Questions/purpose
We used a cadaveric foot model to test the effects of three tibialis anterior tendon transfer techniques on forefoot positioning and production of hindfoot valgus.
Methods
Ten fresh-frozen cadaveric lower legs were used. We applied 150 N tension to the anterior tibial tendon, causing the ankle to dorsiflex. Three-dimensional motions of the first metatarsal, calcaneus, and talus relative to the tibia were measured in intact specimens, and then repeated after each of the three surgical techniques.
Results
Under maximum dorsiflexion, the intact specimens showed 6° (95% CI, 2.2°–9.4°) forefoot supination and less than 3° (95% CI, 0.4°–5.3°) hindfoot valgus motion. All three transfers provided increased forefoot pronation and hindfoot valgus motion compared with intact specimens: the three-incision whole transfer provided 38° (95% CI, 33°–43°; p < 0.01) forefoot pronation and 10° (95% CI, 8.5°–12°; p < 0.01) hindfoot valgus; the split transfer, 28° (95% CI, 24°–32°; p < 0.01) pronation, 9° (95% CI, 7.5°–11°; p < 0.01) valgus; and the two-incision transfer, 25° (95% CI, 20°–31°; p < 0.01) pronation, 6° (95% CI, 4.2°–7.8°; p < 0.01) valgus.
Conclusion
All three techniques may be useful and deliver varying degrees of increased forefoot pronation, with the three-incision whole transfer providing the most forefoot pronation. Changes in hindfoot motion were small.
Clinical Relevance
Our study results show that the amount of forefoot pronation varied for different transfer methods. Supple dynamic forefoot supination may be treated with a whole transfer using a two-incision technique to avoid overcorrection, while a three-incision technique or a split transfer may be useful for more resistant feet. Confirmation of these findings awaits further clinical trials.
We describe the first demonstration of a sub-keV electron recoil energy threshold in a dual-phase liquid argon time projection chamber. This is an important step in an effort to develop a detector ...capable of identifying the ionization signal resulting from nuclear recoils with energies of order a few keV and below. We obtained this result by observing the peaks in the energy spectrum at 2.82keV and 0.27keV, following the K- and L-shell electron capture decay of 37Ar respectively. The 37Ar source preparation is described in detail, since it enables calibration that may also prove useful in dark matter direct detection experiments. An internally placed 55Fe x-ray source simultaneously provided another calibration point at 5.9keV. We discuss the ionization yield and electron recombination in liquid argon at those three calibration energies.
•We measure sub-keV electron recoils in a dual-phase argon time projection chamber.•Ar-37 is produced via neutron irradiation and used as calibration source.•Ar-37 electron captures at 2.82 and 0.27keV are measured together with Fe-55 x-rays.•Spurious single ionization electrons provided absolute calibration of charge signal.•Modified Thomas–Imel model describes low-energy electron-recoils in liquid Ar.
Detailed understanding of the ionization process in noble liquid detectors is important for their use in applications such as the search for dark matter and coherent elastic neutrino-nucleus ...scattering. The response of noble liquid detectors to low-energy ionization events is poorly understood at this time. We describe a new simulation tool which predicts the ionization yield from electronic energy deposits (E<10keV) in liquid Ar, including the dependence of the yield on the applied electric drift field. The ionization signal produced in a liquid argon detector from 37Ar beta decay and 55Fe X-rays has been calculated using the new model.
The design of a neutron source capable of producing 24 and 70keV neutron beams with narrow energy spread is presented. The source exploits near-threshold kinematics of the 7Li (p,n)7Be reaction while ...taking advantage of the interference ‘notches’ found in the scattering cross-sections of iron. The design was implemented and characterized at the Center for Accelerator Mass Spectrometry at Lawrence Livermore National Laboratory. Alternative filters such as vanadium and manganese are also explored and the possibility of studying the response of different materials to low-energy nuclear recoils using the resultant neutron beams is discussed.
Purpose
Previous reports have demonstrated diminished size of the hindfoot bones in patients with idiopathic clubfoot deformity. However, no study has quantified the percentage of hypoplasia as a ...function of early growth, during the brace phase of Ponseti treatment.
Methods
We measured the dimensions of ossified structures on radiographs in patients with unilateral Ponseti-treated clubfeet to determine changes in the percentage of hypoplasia between two and four years of age.
Results
The degree of hypoplasia varied among the osseous structures in Ponseti-treated clubfeet at age two years, with greater hypoplasia being observed in the talus (7.3%), followed by calcaneus (4.9%) and the cuboid (4.8%). Overall, the degree of hypoplasia diminished by four years, such that the degree of hypoplasia was greatest in the talus (4.2%) and the calcaneus (4.2%) followed by the cuboid (0.6%). At four years of age, the greatest degree of hypoplasia persisted in the talus and calcaneus.
Conclusions
Changes occurred in the size of the ossification of hindfoot bones between two and four years of age, and the observed changes in the percentage of hypoplasia varied among the different structures. At four years of age, the greatest percentage of hypoplasia was observed in the talus and calcaneus at values similar to those previously reported in skeletally mature patients. The results suggested that the relative difference in size of the feet may be expected to remain constant in a child with a unilateral clubfoot after this age.
The behavior of the Indian meal moth Plodia interpunctella on maize genotypes differing in embryo development, both on whole and longitudinally sectioned kernels, was studied. In the test with whole ...kernels, damage was very low or absent, and only viviparous mutants were significantly attacked. However, 100% damage was observed in all genotypes on longitudinally sectioned kernels. In this test, mutant seeds lacking embryos were less damaged and showed the lowest mean number of adult insects. These results indicate that larval penetration is influenced by the embryo properties and first shows that the employment of genetic variants is a valuable approach to study insect behavior and an opportunity to highlight maize genotypes with characteristics that can minimize quality reduction caused by insect attacks. --Keywords: Indian meal moth, maize embryo, maize seed mutants--
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