Giant cell formation produced by laser microbeam irradiation of chromatin in Chinese hamster cells

A pulsed laser microbeam of wavelength 532 nm was used to produce visible small lesions in the nucleoplasm or in the cytoplasm of V79 Chinese hamster cells. Transmission electron microscopy (TEM) of microirradiated nuclei showed that the lesions were produced within the nucleus and comprised between 0.2 and 0.5% of the total chromatin. Serial sections above and below the lesion site did not reveal any detectable chromatin damage, indicating that a visible lesion was restricted to the focal point of the beam. Whereas cells microirradiated anywhere in the cytoplasm showed normal clonal growth with few exceptions, the cells containing nuclear lesions did not enter mitosis at the time of unirradiated controls. Instead they formed giant cells in a high percentage of cases (72/99). The DNA content of these cells was considerably increased suggesting polyploidization. In some cases, division of giant cells was observed resulting in non-viable daughter cells containing micronuclei. Further evidence that the induction of giant cell formation depends on chromatin damage was obtained by microirradiation of chromosomes in anaphase. Here, giant cell formation was observed in the daughter cell which received microirradiated chromatin, whereas microirradiation of cytoplasm between the moving sets of chromosomes did not affect subsequent divisions of both daughter cells. Our data point out that loss of reproductive integrity and giant cell formation can be induced by damage at many sites of the chromosome complement

\u3cem\u3eMartin v. Mott\u3c/em\u3e and the Establishment of Executive Emergency Authority

In August of 1814, a New York farmer named Jacob E. Mott refused to rendezvous with the militia pursuant to the orders of Governor Daniel D. Tompkins as commanded by President James Madison. In 1818, Mott was court martialed and fined ninety-six dollars. One year later, Mott brought an action in replevin in the New York state courts to recover chattel taken from him by a deputy marshal in lieu of the ninety-six dollars. Both the New York trial and appellate courts sided with Mott. In a unanimous opinion authored by Justice Joseph Story, the Supreme Court of the United States reversed and held the marshal’s avowry sufficient. Justice Story’s opinion reiterated the authority of the federal executive, and began a line of cases that culminated in our modern approach to unilateral executive emergency powers

Measuring trade in value added with Firm-Level Data. NBB Working Paper No 378, November 2019

Global Value Chains have proliferated economic policy debates. Yet a key concept – trade in value added –is likely mismeasured because of sectoral aggregation bias stemming from reliance on inputoutput tables. This paper uses comprehensive firm-level data on both domestic and international transactions to study this bias. We find that sectoral aggregation leads to overstated trade in value added and, correspondingly, understated import content of gross exports. The economic magnitude of the estimated bias varies from moderate to large – at 2-5 p.p. of gross exports for Belgium and 17 p.p. for China. We study how the interplay between within-sector heterogeneities in firm import and export intensities and firm size determine the magnitude of the sectoral aggregation bias

Super-Fast Distributed Algorithms for Metric Facility Location

This paper presents a distributed O(1)-approximation algorithm, with expected-$O(\log \log n)$ running time, in the $\mathcal{CONGEST}$ model for the metric facility location problem on a size-$n$ clique network. Though metric facility location has been considered by a number of researchers in low-diameter settings, this is the first sub-logarithmic-round algorithm for the problem that yields an O(1)-approximation in the setting of non-uniform facility opening costs. In order to obtain this result, our paper makes three main technical contributions. First, we show a new lower bound for metric facility location, extending the lower bound of B\u{a}doiu et al. (ICALP 2005) that applies only to the special case of uniform facility opening costs. Next, we demonstrate a reduction of the distributed metric facility location problem to the problem of computing an O(1)-ruling set of an appropriate spanning subgraph. Finally, we present a sub-logarithmic-round (in expectation) algorithm for computing a 2-ruling set in a spanning subgraph of a clique. Our algorithm accomplishes this by using a combination of randomized and deterministic sparsification.Comment: 15 pages, 2 figures. This is the full version of a paper that appeared in ICALP 201

Plasma and cavitation dynamics during pulsed laser microsurgery in vivo

We compare the plasma and cavitation dynamics underlying pulsed laser microsurgery in water and in fruit fly embryos (in vivo) - specifically for nanosecond pulses at 355 and 532 nm. We find two key differences. First, the plasma-formation thresholds are lower in vivo - especially at 355 nm - due to the presence of endogenous chromophores that serve as additional sources for plasma seed electrons. Second, the biological matrix constrains the growth of laser-induced cavitation bubbles. Both effects reduce the disrupted region in vivo when compared to extrapolations from measurements in water.Comment: 9 pages, 5 figure

An histochemical and ultrastructural analysis of the dermal chromatophores of the variant ranid blue frog

Integument from blue and green areas of the variant blue frog were analyzed biochemically for pteridines and carotenoids. Solvent extraction and absorption spectrophotometry indicated that Β carotene was greatly reduced in the blue skin, and present in high quantities in the green skin of the blue frog. Thin layer and paper chromatography indicated that the pteridines were almost totally lacking in the blue skin, and present in normal quantities in the green skin of the blue frog. Light and electron microscopy indicated that the xanthophore pigment cells were either greatly altered or absent from the blue integument and present in the green integument. The fine structure of the xanthphores of the green integument contained the normal ultrastructural components of xanthopores found in regular green integument. The blue integument contained an abnormal cell type that occupied the position in the dermal chromatophore unit normally held by the xanthophores. The possibility of these cells being abnormal xanthophores or some other cell type is discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/50255/1/1051320205_ftp.pd