Science Progress (2005), 88(1)

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Science Progress (2005), 88(1), 1–16

Concepts of renormalization in physics

JEAN ALEXANDRE

ABSTRACT

A non technical introduction to the concept of renormalization is given, with

an emphasis on the energy scale dependence in the description of a physical

system. We first describe the idea of scale dependence in the study of a

ferromagnetic phase transition, and then show how similar ideas appear in

particle physics. This short review is written for non-particle physicists

and your students aiming at studying Particle Physics.

Keywords: renormalization, ferromagnetic phase transition, particle

physics

Science Progress (2005), 88(1), 17–48

Molecular engineering of surfaces

using self-assembled monolayers

GEORGE M. WHITESIDES, JENNAH K. KRIEBEL

AND J. CHRISTOPHER LOVE

ABSTRACT

The self-assembly of molecules into structurally organized monolayers

(SAMs) uses the flexibility of organic chemistry and coordination chemistry

to generate well-defined, synthetic surfaces with known molecular and

macroscopic properties. The process of designing monolayers with a specified

structure gives a high level of control over the molecular-level composition in

the direction perpendicular to a surface; soft lithographic technique gives

useful (if lower) resolution in the plane of the surface. Alkanethiolates

adsorbed on gold, silver, mercury, palladium and platinum are currently the

best-defined systems of SAMs. They provide substrates for a number of

applications –from studies of wetting and electron transport to patterns for

growing mammalian cells. SAMs have made organic surfaces a central part

of surface science. Understanding the principles by which they form, and

connecting molecular-level structure with macroscopic properties, opens a

wide range of areas to study and exploitation.

Keywords: self-assembled monolayers, SAMs, organic films, alkanethiolates,

molecular electronics, surface science, nanotechnology

Science Progress (2005), 88(1), 49–69

An introduction to RNA-mediated

gene silencing

MARK GEANACOPOULOS

ABSTRACT

Careful analysis of cases where introduction of additional copies of endogenous

genes caused coordinate silencing of both the transgene and the

endogenous gene laid the ground work for the discovery of RNA-mediated

silencing. Silencing begins with the expression and recognition of double-stranded

RNA, which is cleaved into short RNAs that recognize, by

complementarity, sequences that are targets for down regulation. An RNA

target can be regarded (post-transcriptional gene silencing), but the small

RNAs can also direct the sequence-specific modification of DNA and

chromatin. RNA-mediated gene silencing in eukaryotes may have originated

as surveillance mechanism to protect the organism from transposable

elements and viruses and then evolved to specify chromosomal modifications

and to regulate expression of a significant fraction of endogenous genes by

microRNAs. This review seeks to furnish the student and non-expert with

some idea of how RNA-mediated silencing was discovered and a broad

overview of the present state of knowledge.

Keywords: gene silencing, RNA interference, dicer, RISC, RNA-mediated

gene silencing, microRNAs, co-supression