Walter Campbell:A distinguished life

An efficient and simple synthesis approach to form stable (68) Ga-labeled nanogels is reported and their fundamental properties investigated. Nanogels are obtained by self-assembly of amphiphilic statistical prepolymers derivatised with chelating groups for radiometals. The resulting nanogels exhibit a well-defined spherical shape with a diameter of 290 +/- 50 nm. The radionuclide (68) Ga is chelated in high radiochemical yields in an aqueous medium at room temperature. The phagocytosis assay demonstrates a highly increased internalization of nanogels by activated macrophages. Access to these (68) Ga-nanogels will allow the investigation of general behavior and clearance pathways of nanogels in vivo by nuclear molecular imaging

The Eastwood-Singer gauge in Einstein spaces

Electrodynamics in curved spacetime can be studied in the Eastwood--Singer gauge, which has the advantage of respecting the invariance under conformal rescalings of the Maxwell equations. Such a construction is here studied in Einstein spaces, for which the Ricci tensor is proportional to the metric. The classical field equations for the potential are then equivalent to first solving a scalar wave equation with cosmological constant, and then solving a vector wave equation where the inhomogeneous term is obtained from the gradient of the solution of the scalar wave equation. The Eastwood--Singer condition leads to a field equation on the potential which is preserved under gauge transformations provided that the scalar function therein obeys a fourth-order equation where the highest-order term is the wave operator composed with itself. The second-order scalar equation is here solved in de Sitter spacetime, and also the fourth-order equation in a particular case, and these solutions are found to admit an exponential decay at large time provided that square-integrability for positive time is required. Last, the vector wave equation in the Eastwood-Singer gauge is solved explicitly when the potential is taken to depend only on the time variable.Comment: 13 pages. Section 6, with new original calculations, has been added, and the presentation has been improve

The Serendipitous Discovery of a Group or Cluster of young Galaxies at z=2.40 in Deep Hubble Space Telescope WFPC2 Images

We report the serendipitous discovery of a group or cluster of young galaxies at $z\simeq$2.40 in a 24-orbit HST/WFPC2 exposure of the field around the weak radio galaxy 53W002. Potential cluster members were identified on ground-based narrow-band redshifted Ly$\alpha$ images and confirmed via spectroscopy. In addition to the known weak radio galaxy 53W002 at z=2.390, two other objects were found to have excess narrow-band Ly$\alpha$ emission at $z\simeq$2.40. Both have been spectroscopically confirmed, and one clearly contains a weak AGN. They are located within one arcminute of 53W002, or $\sim0.23h_{100}^{-1}$Mpc ($q_o$=0.5) at $z\simeq$2.40, which is the physical scale of a group or small cluster of galaxies. Profile fitting of the WFPC2 images shows that the objects are very compact, with scale lengths $\simeq$0\farcs 1 ($\simeq0.39h_{100}^{-1}$kpc), and are rather faint (luminosities < L*), implying that they may be sub-galactic sized objects. We discuss these results in the context of galaxy and cluster evolution and the role that weak AGN may play in the formation of young galaxies.Comment: Accepted for publication in The Astrophysical Journal (Letters). 13 pages of gzip compressed and uuencoded PS. Figures are available at http://www.phys.unsw.edu.au/~spd/bib.htm

Optical/near-infrared selection of red QSOs: Evidence for steep extinction curves towards galactic centers?

We present the results of a search for red QSOs using a selection based on optical imaging from SDSS and near-infrared imaging from UKIDSS. For a sample of 58 candidates 46 (79%) are confirmed to be QSOs. The QSOs are predominantly dust-reddened except a handul at redshifts z>3.5. The dust is most likely located in the QSO host galaxies. 4 (7%) of the candidates turned out to be late-type stars, and another 4 (7%) are compact galaxies. The remaining 4 objects we could not identify. In terms of their optical spectra the QSOs are similar to the QSOs selected in the FIRST-2MASS red Quasar survey except they are on average fainter, more distant and only two are detected in the FIRST survey. We estimate the amount of extinction using the SDSS QSO template reddened by SMC-like dust. It is possible to get a good match to the observed (restframe ultraviolet) spectra, but for nearly all the reddened QSOs it is not possible to match the near-IR photometry from UKIDSS. The likely reasons are that the SDSS QSO template is too red at optical wavelengths due to contaminating host galaxy light and that the assumed SMC extinction curve is too shallow. Our survey has demonstrated that selection of QSOs based on near-IR photometry is an efficent way to select QSOs, including reddened QSOs, with only small contamination from late-type stars and compact galaxies. This will be useful with ongoing and future wide-field near-IR surveys such as the VISTA and EUCLID surveys. [Abridged]Comment: 74 pages, 6 figures. Accepted for for publication in ApJ

The metal absorption systems of the Hubble Deep Field South QSO

The Hubble Deep Field South (HDFS) has been recently selected and the observations are planned for October 1998. We present a high resolution (FWHM $\simeq 14$ \kms) spectrum of the quasar J2233--606 ($z_{em}\simeq2.22$) which is located 5.1 arcmin East of the HDFS. The spectrum obtained with the New Technology Telescope redward of the Lyman--$\alpha$ emission line covers the spectral range 4386--8270 \AA. This range corresponds to redshift intervals for CIV and MgII intervening systems of $z=1.83-2.25$ and $z=0.57-1.95$ respectively. The data reveal the presence of two complex intervening CIV systems at redshift $z=1.869$ and $z=1.943$ and two complex associated ($z_{abs} \approx z_{em}$) systems. Other two CIV systems at $z=1.7865$ and $z=2.077$, suggested by the presence of strong Lyman--$\alpha$ lines in low resolution ground based and Hubble Space Telescope (HST) STIS observations (Sealey et al. 1998) have been identified. The system at $z=1.943$ is also responsible for the Lyman limit absorption seen in the HST/STIS spectrum. The main goal of the present work is to provide astronomers interested in the Hubble Deep Field South program with information related to absorbing structures at high redshift, which are distributed along the nearby QSO line of sight. For this purpose, the reduced spectrum, obtained from three hours of integration time, has been released to the astronomical community.Comment: revisited version accepted for publication by Astronomical Journal; minor changes; typographical errors corrected; results and discussion unchange

Using Gravitational Lensing to study HI clouds at high redshift

We investigate the possibility of detecting HI emission from gravitationally lensed HI clouds (akin to damped Lyman-$\alpha$ clouds) at high redshift by carrying out deep radio observations in the fields of known cluster lenses. Such observations will be possible with present radio telescopes only if the lens substantially magnifies the flux of the HI emission. While at present this holds the only possibility of detecting the HI emission from such clouds, it has the disadvantage of being restricted to clouds that lie very close to the caustics of the lens. We find that observations at a detection threshold of 50 micro Jy at 320 MHz (possible with the GMRT) have a greater than 20% probability of detecting an HI cloud in the field of a cluster, provided the clouds have HI masses in the range 5 X 10^8 M_{\odot} < M_{HI} < 2.5 X 10^{10} M_{\odot}. The probability of detecting a cloud increases if they have larger HI masses, except in the cases where the number of HI clouds in the cluster field becomes very small. The probability of a detection at 610 MHz and 233 MHz is comparable to that at 320 MHz, though a definitive statement is difficult owing to uncertainties in the HI content at the redshifts corresponding to these frequencies. Observations at a detection threshold of 2 micro Jy (possible in the future with the SKA) are expected to detect a few HI clouds in the field of every cluster provided the clouds have HI masses in the range 2 X 10^7 M_{\odot} < M_{HI} < 10^9 M_{\odot}. Even if such observations do not result in the detection of HI clouds, they will be able to put useful constraints on the HI content of the clouds.Comment: 21 pages, 7 figures, minor changes in figures, accepted for publication in Ap

A controlled study of the effect of domiciliary tuberculosis chemotherapy programme in a rural community in South India

To study thc ellicttq of a domiciliary drug-therapy programme in the control of tuberculosis in a rural community, an investigation was set lip in 1958 under the auspices of the Indian Council of Medlenl I{C!IClln:h ill 12 towns with populations ranging from 6000 to 25000, all within 160 km of Madanapallc (Andhra Pradt'Sh). The prevalences of bacillary and radioloj.(ic~ll cases of pulmonary tuberculosis in adults (llgcd 15 )T or more) were estimated in .. ch town by carrying out a hase-Iine random sample survey iu 1959; also, the prevalences of tuberculous infcl'tion in all schoolchildrt,n aged 5 to 9yr wen' estimated. These thn.'t' in.dices of prevalence were used to rank the 12 towns and tben ndomlyallocate them into two l'omparable groups of 6 towns each, designated as 'Ireatment' and '~:ontmJ' tOWIlS. In treatment tOWIIS, intensi"e case finding ,,-as undertaken hy means of 2 X-ray surveys (suney I during 1960-61 and survey II during 1962-64) l'ovcring alllldults, sputum examinations by microSl'op' Hnd culture when indicated, and eriodic follow lip of all 'suspect' cases with X-ray and SPlltuDl examinations. All bacillary cases were offered domiciliary treatment for onc ~'ear with isoniazid and PAS in the J treatment IOWll~ (selected at random) a.nd with isoniazid alone in the other 3 town.·,. Of 148 2easc~ eligible for trcat-at ment in tJlC 6 treatment towns, 15 per l'en.t refused treatment nd 29 per cent discontin.ued chemotherapy prematurely. In lhe rontrol towns, 0.0 spcdal faeililies for di~gn()sis 01' calment ,vere introduced, and patients w~'re left to the routine treatment facilities aV:lilahk' locally. A tuberculosis prcntlcm:e survey (~ul'l'ey Ill) t'O\'cri~ all adults was 1.1lrried out iD 9.1112 towns during 1965-68, am! lhi:; ~:l." followed hy a random tuberculin sample survey during 1966-69. The overall results of treatment at the end of one year ,,'eJ'e.' (i) among cases initially positive hy micro~opy, 10 per' nt died, 33 per locnt rcmllincd sputum-positive IUld 51 per cent became sputum-negative in INH-PAS towns, the mrl'lsponding percentages fur INH lowns being 15, 48 and 37 per cent respectivel~'; (ii): moug cases initially positive by culture ()nJy, 6 per ent died, 26 J1er cent remained sputum-posithc and 68 per cent became sputum negative in lNH-PAS towns, tbe correspondi percentages for tile INH town~ being 1, 38 an. 55 IJer cent respectively. All the bacillary cases (treated or untrcatt'lf) were followed up and their status at the end of 5 yr was 40.4 per cent dead, 18.2 per cent sputum-positive and 41.4 pCT cent sputum-ne'~ative. Spntum status at one year had considerable prognostic value. Of 532 sputum-negative ea .. at one year, 18 per l'ent were dead, 16 per CCDt sputuDl-posithe and 66 per cent sputum-ncgath'e 5 yr aftenvards, where'd!! the corresponding percentagt'S for (JIC 319 sputum-positive cases at one year were 56, 20 llnd 24 respectively. There was an intennl of about 2l ~'r between sunc)' [ and survey [[ and ahout 4 yr between survey [J and survey 111 in the 6 treatmellt towns. The prevalence of badllary cases in these sUr\'eys was age-standardised, cousidering separately l'UseS found hy microscopy and cases found by culture only. The lJlean prevalence of cases (Wsitive hy microscopy in the 6 treatment towns was 6.81 per thousand in survey I and it decre~sed significanUy (P < 0,01) to 5.01 in survey nand 4.83 in survey Ill. Change of culture technique during the course of the investi~ation complicated the interpretation of prcva· lenl'C:l of culture-positive cases. BetwCCR the 1959 base-line survey and tbe resurvey in 1965·68, the prevalence ()f smear-positive tuberculosis decreas~d from 5.92 per thousand adults to 4.78 in the 6 treatment towns, and similarly from 5.72 to 4.21 in the 6 control towns. The prcvalenl-e of 'culture only-positive' cases was 3.85 and 2.44 per thousand adults in the treatment and control towns respectively at the base-line survey and (with the more sesnsitive culture technique) 4.92 and 4.82 per thousand adults at the resurvey in 1965·68. Lastly, tho tuberculin survey in 1966·69 did not I" .,'ell! any' significant differences between the tr t· ment and the control towns. The inability ofthe domiciliary treatment programme to make an impact on the prevalefl:lc of tuberculosis in the rural community around Madanapalle is a finding that has cOllsidera lie siJ,(nilicance in the context of the tubercUlosis control programme in fndia; the rl'asons for the failure aud its implications are discussed

Rotating light, OAM paradox and relativistic complex scalar field

Recent studies show that the angular momentum, both spin and orbital, of rotating light beams possesses counter-intuitive characteristics. We present a new approach to the question of orbital angular momentum of light based on the complex massless scalar field representation of light. The covariant equation for the scalar field is treated in rotating system using the general relativistic framework. First we show the equivalence of the U(1) gauge current for the scalar field with the Poynting vector continuity equation for paraxial light, and then apply the formalism to the calculation of the orbital angular momentum of rotating light beams. If the difference between the co-, contra-, and physical quantities is properly accounted for there does not result any paradox in the orbital angular momentum of rotating light. An artificial analogue of the paradoxical situation could be constructed but it is wrong within the present formalism. It is shown that the orbital angular momentum of rotating beam comprising of modes with opposite azimuthal indices corresponds to that of rigid rotation. A short review on the electromagnetism in noninertial systems is presented to motivate a fully covariant Maxwell field approach in rotating system to address the rotating light phenomenon.Comment: No figure