Erratum: Emittance Preservation in an Aberration-Free Active Plasma Lens [Phys. Rev. Lett. 121, 194801 (2018)].

This corrects the article DOI: 10.1103/PhysRevLett.121.194801.

Emittance Preservation in an Aberration-Free Active Plasma Lens.

Active plasma lensing is a compact technology for strong focusing of charged particle beams, which has gained considerable interest for use in novel accelerator schemes. While providing kT/m focusing gradients, active plasma lenses can have aberrations caused by a radially nonuniform plasma temperature profile, leading to degradation of the beam quality. We present the first direct measurement of this aberration, consistent with theory, and show that it can be fully suppressed by changing from a light gas species (helium) to a heavier gas species (argon). Based on this result, we demonstrate emittance preservation for an electron beam focused by an argon-filled active plasma lens.

A compact, low cost Marx bank for generating capillary discharge plasmas.

We describe in detail a low power Compact Marx Bank (CMB) circuit that can provide 20 kV, 500 A pulses of approximately 100-200 ns duration. One application is the generation of capillary discharge plasmas of density ≈1018 cm-3 used in laser plasma accelerators. The CMB is triggered with a high speed solid state switch and gives a high voltage output pulse with a ns scale rise time into a 50 Ω load (coaxial cable) with <4 ns voltage jitter. Its small size (10 cm × 25 cm × 5 cm) means that it can be placed right next to the capillary discharge in the target chamber to avoid the need to impedance match. The electrical energy required per discharge is <1 J, and the CMB can be run at shot repetition rates of ≳1 Hz. This low power requirement means that the circuit can easily be powered by a small lead acid battery and, therefore, can be floated relative to laboratory earth. The CMB is readily scalable and pulses >45 kV are demonstrated in air discharges.

Congenital hypothyroidism.

This paper presents a case report of congenital hypothyroidism that illustrates some of the issues in screening for this disorder. Congenital hypothyroidism has several causes, the most common of which is thyroid dysgenesis. Most affected infants have no historical clues or physical findings to suggest diagnosis. Neonatal screening combining thyroxine and thyrotropin screening have resulted in increased detection, although false-negatives do occur, and the physician must carefully observe all newborns for the findings of congenital hypothyroidism. Early treatment improves the prognosis considerably. This paper reviews the pathophysiology, diagnosis, and treatment of congenital hypothyroidism.

Group G streptococcal colonization and sepsis in neonates.

Group G streptococci were isolated from the blood of seven neonates over a five-year period at the New York Hospital. All but two were born near term. All presented clinically with signs and symptoms of neonatal sepsis. Only one case was associated with a major complication--epidermolysis bullosa; this patient died. Two presented as late-onset sepsis at 11 and 12 days of age. Six of the seven responded promptly to antibiotic therapy. A one-year survey was carried out of colonization with groups B and G streptococci at the time of discharge (day 3). Colonization with group G streptococci varied between 41 and 76% of babies each month. Group B streptococcal colonization ranged between 1 and 11%. Statistical analysis suggested that colonization with these organisms may be a mutually exclusive phenomenon.