Harvardiana : March Song

https://digitalcommons.library.umaine.edu/mmb-vp/4967/thumbnail.jp

Production of intense, coherent, tunable narrow‐band lyman‐alpha radiation

Nearly transform limited pulses of 1216 Å radiation have been generated by sum frequency generation in 0.1 to 10 torr of mercury vapor. The summed input beams, consisting of photons at 3127 Å and 5454 Å originate in 1 MHz band‐width ring‐dye laser oscillators. The beams are amplified in pulsed‐dye amplifiers pumped by the frequency doubled output of a Nd:YAG laser. The 3127 Å photons are tuned to be resonant with the two‐photon 61S to 71S mercury transition. The VUV radiation can be tuned by varying the frequency of the third non‐resonant photon. We have also observed difference frequency generation at 2193 Å and intense fluorescence from the 61P state at 1849 Å. We have studied the intensity and linewidth dependence of the 1849 Å fluorescence and 1216 Å sum frequency signals on input beam intensity, mercury density, and buffer gas pressure and composition.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87716/2/49_1.pd

High intrinsic radiosensitivity of a newly established and characterised human embryonal rhabdomyosarcoma cell line.

A new human rhabdomyosarcoma cell line (HX170c) has been established from a paratesticular embryonal tumour in a 5-year-old male. The cells grew as an adherent monolayer with a doubling time of 32 h and showed pleomorphic features. Intermediate filament analysis revealed the line to be mesenchymal in origin (reactivity to vimentin and desmin antibodies). The line was tumorigenic in nude mice, possessed elevated levels of creatine phosphokinase (mainly of the MM isoenzyme form) and had a near diploid mean chromosome number of 50. In vitro cell cloning determinations gave colony forming efficiencies of 0.01% in soft agar and 24% in a monolayer anchorage-dependent assay. Radiosensitivity determinations using a monolayer clonogenic assay with feeder layer support showed the cells to be among the more radiosensitive human tumour cell types (surviving fraction at 2 Gy of 0.26) that have been investigated. Furthermore, experiments utilising continuous low dose rate radiation at 3.2 cGy min-1, showed that, under these experimental conditions, the cells possessed only a very low capacity to recover from radiation-induced damage (dose reduction factor at 1% cell survival of 1.07 for 150 versus 3.2 cGy min-1). As other human tumour cells of an embryonal cell origin (e.g. neuroblastoma and germ cell tumours of the testis) have also been shown to be radiosensitive it appears that sensitivity to radiation may be a common property of this group of tumours

KNEE SEPARATION DISTANCE AND QUADRICEPS AND HAMSTRINGS STRENGTH DURING DROP VERTICAL JUMP LANDINGS

Non-contact anterior cruciate ligament (ACL) injury is common particularly in female athletes during jump landing tasks. Ligament dominance occurs when the muscles cannot control knee movement sufficiently thus increasing medial knee motion. Preferential use of the quadriceps during landing and greater strength compared to the hamstrings also increase the load placed on the ACL (Dugan, 2005). Noyes et al. (2005) measured knee separation distance during jump landings finding an increase after neuromuscular training. The aim of this study was to examine the relationship between knee separation distance during drop jump landing and hamstrings and quadriceps strength in female athletes