bluuebunny/crossref_metadata_2025 huggingface dataset:
Postpartum Hemorrhage Prevention: A Case Study in Northern Rural Honduras
Authors: Low Lisa Kane , Bailey Joanne Motiño , Sacks Emma , Medina Lilian , Piñeda Hector Oqueli Lopez
Published: January 2008

Postpartum hemorrhage (PPH) is the leading cause of maternal mortality globally. Safe Motherhood policies have been directed towards the reduction of PPH by recommending active management of third‐stage labor as the standard of care. One component of active management involves routine use of a uterotonic agent within 1 minute of the delivery of the baby. A case study at Clínica Materno‐Infantil, a free‐standing public birth center in Honduras, is presented, focusing on methods to reduce PPH. The nursing staff was trained to estimate blood loss and in methods to manage PPH, including elements of active management of the third stage of labor. Medical records were reviewed and an analysis of PPH management compared to estimated blood loss (EBL) was conducted. There was no significant correlation between PPH management techniques and EBL (r = .368). There was a statistically significant (P < .001) correlation between oxytocin administration and lower EBL (r = –.232), indicating that there was less blood loss when oxytocin was administered. At Clínica Materno‐Infantil, routine use of a uterotonic agent appears beneficial and further implementation of active management of the third stage of labor appears warranted.
STATES WITH MIDWIFERY REIMBURSEMENT LAWS FAVORABLY AFFECT MIDWIFERY PRACTICE AND NEONATAL/INFANT MORTALITY RATES
Authors: Bond Sharon , Bond Sharon
Published: January 2008

Miller AR. The impact of midwifery‐promoting public policies on medical interventions and health outcomes. Adv Econ Anal Pol 2006; 6(1):Article 6. Available at: www.bepress.combejeapadvancesvol6iss1art6.
ELECTIVE INDUCTIONS IN PRIMIPARAS INCREASE LIKELIHOOD OF CESAREAN
Authors: Bond Sharon
Published: January 2008

Wilson BL. Assessing the effects of age, gestation, socioeconomic status, and ethnicity on labor inductions. J Nurs Scholarsh 2007;39(3):208–13.
A comparative study of the filamentation and Weibel instabilities and their cumulative effect. I. Non-relativistic theory
Authors: LAZAR M. , SMOLYAKOV A. , SCHLICKEISER R. , SHUKLA P. K.
Published: January 2008

A comparative study of the electromagnetic instabilities in anisotropic unmagnetized plasmas is undertaken. The instabilities considered are the filamentation and Weibel instability, and their cumulative effect. Dispersion relations are derived and the growth rates are plotted systematically for the representative cases of non-relativistic counterstreaming plasmas with isotropic or anisotropic velocity distributions functions of Maxwellian type. The pure filamentation mode is attenuated by including an isotropic Maxwellian distribution function. Moreover, it is observed that counterstreaming plasmas can be fully stabilized by including bi-Maxellian distributions with a negative thermal anisotropy. This effect is relevant for fusion plasma experiments. Otherwise, for plasma streams with a positive anisotropy the filamentation and Weibel instabilities cumulate leading to a growth rate by orders of magnitude larger than that of a simple filamentation mode. This is noticeable for the quasistatic magnetic field generated in astrophysical sources, and which is expected to saturate at higher values and explain the non-thermal emission observed.
Determination of new types of DNA lesions in human sperm
Authors: Badouard C. , Ménézo Y. , Panteix G. , Ravanat J.L. , Douki T. , Cadet J. , Favier A.
Published: January 2008

Careful attention has been focused recently on DNA quality in human IVF. Therefore a variety of methods has been developed to evaluate DNA integrity, especially concerning fragmentation. Using liquid chromatography and mass spectrometry (LC/MS/MS) for our best sperm samples, we have established reference values for several oxidative lesions, in order to gain insights into the cause of DNA lesions. Besides 8-oxodeoxyguanosine, we found rather high levels of two ethenonucleosides: 1,N6-ethenoadenosine and 1,N2-ethenoguanosine. These compounds probably arise from a reaction with 4-hydroxy-2-nonenal, the main aldehyde compound released during lipid peroxidation, or after occupational exposure to vinyl chloride. The quantity of chlorinated bases detected is low. All of this decay has to be repaired by the oocytes at the time of fertilization or immediately after. This aspect should not be overlooked in assisted reproductive technology, in order to understand risks and limitations.
Heparin effect onin vitronuclear maturation of bovine oocytes
Authors: Flores-Alonso Juan Carlos , Lezama-Monfil Leticia , Sánchez-Vázquez María Luisa , Reyes Rosalina , Delgado Néstor M.
Published: January 2008

Oocytes undergo numerous biochemical and morphological changes during their development from preantral to preovulatory phases.In vitrostudies have suggested several compounds that might induce oocyte maturation. Heparin is a natural component of ooplasm, follicular fluid and uterine fluid and previous studies indicated that it might act as a chromatin maturation factor in bovine oocytes. We tested this hypothesisin vitroby timing germinal vesicle breakdown (GVBD) and first polar body (PB) formation without any other natural or introduced factors that might influence the rate of oocyte maturation. We also determined if these oocytes could be fertilized.

Bovine oocytes were incubated in a salt medium and TCM 199 supplemented with different concentrations of heparin for 24 h at 37.5 °C in a humidified atmosphere of 5% CO2. With 1.0 and 6.5 mg/ml heparin, the time of GVBD was reduced from 4.7 ± 1.1 h to about 1.5 h and the time of first PB formation was reduced from 22.0 ± 1.1 h to 9.0–11.0 h in salt medium. In TCM 199, only 6.5 mg/ml heparin significantly reduced the time of PB formation. In both incubation media, 1.0 and 6.5 mg/ml heparin induced GVBD, extrusion of the first PB and formation of the metaphase II nucleus. Moreover, heparin did not interfere with the fertilization of oocytes matured in TCM 199. Based on the results, we propose that heparin plays an important role in the rearrangement of the oocyte chromatin and acts as an oocyte maturation factor.
Production of buffalo embryos using oocytes from in vitro grown preantral follicles
Authors: Gupta P.S.P. , Ramesh H.S. , Manjunatha B.M. , Nandi S. , Ravindra J.P.
Published: January 2008

The present study examines the use of buffalo preantral follicles as a source of oocytes for in vitro embryo production. Preantral follicles were isolated from abattoir-derived buffalo ovaries and were grown for 100 days in five different culture systems: (1) minimum essential medium (MEM); (2) coconut water; (3) MEM + ovarian mesenchymal cell (OMC) co-culture; (4) MEM + granulosa cell (GC) co-culture; or (5) MEM + cumulus cell (CC) co-culture. Low growth rates for the preantral follicles were observed when follicles were cultured in MEM or coconut water medium. Moderate growth rates were seen for OMC and GC co-cultures, and high rates of growth were observed when follicles were grown in CC co-culture. The survival of preantral follicles was low in the MEM culture (<25%), but was over 75% in the other culture systems. Oocytes were not recovered from the MEM group, while an oocyte recovery rate of 80–100% was observed when the follicles were cultured with coconut water/somatic cells. Transferable embryos could be produced only with the oocytes obtained from preantral follicles grown in the OMC and CC co-culture systems. This study demonstrates, for the first time, that it is possible to produce buffalo embryos by in vitro fertilization of oocytes derived from in vitro grown preantral follicles.
Effects of sucrose treatment on the development of mouse nuclear transfer embryos with morula blastomeres as donors
Authors: Zhang Gang , Sun Qing-Yuan , Chen Da-Yuan
Published: January 2008

In this study, nuclear transfer (NT) embryos were produced by using C57Bl/6 mouse morula blastomeres and Kunming mouse metaphase II (MII) oocytes as donors and recipients, respectively, to investigate the effects of sucrose treatment of MII oocytes with different concentrations on the manipulation time of NT, electrofusion and the in vitro and in vivo development of reconstructed embryos. The results demonstrated that: (i) when the oocytes were enucleated with 1, 2 and 3% sucrose treatment, respectively, the enucleating rates were not affected by the different sucrose concentrations, but the manipulation time had significant difference and the mean nuclear transfer manipulation times of every oocyte were 180 ± 10 s, 130 ± 10 s and 120 ± 10 s, respectively; (ii) different sucrose concentrations had no significant effects on the fusion rate and the in vitro developmental potential of the NT embryos (p > 0.05). Furthermore, 59 embryos were transplanted into the oviducts of two recipients. In the end, three dead full-term developed fetuses were obtained on 21 days post coitus (dpc). These results suggested that the mouse MII oocytes enucleated via sucrose treatment might be an alternative source for mouse cloning and could support the embryonic NT embryos developed to term in vivo.
Global poly(A) mRNA expression profile measured in individual bovine oocytes and cleavage embryos
Authors: Biase F.H. , Fonseca Merighe G. Krempel , Santos Biase W. Karyna Freitas , Martelli L. , Meirelles F. Vieira
Published: January 2008

The objective of this article was to estimate quantitative differences for GAPDH transcripts and poly(A) mRNA: (i) between oocytes collected from cumulus–oocyte complexes (COCs) qualified morphologically as grades A and B; (ii) between grade A oocytes before and afterin vitromaturation (IVM); and (iii) amongin vitro-produced embryos at different developmental stages. To achieve this objective a new approach was developed to estimate differences between poly(A) mRNA when using small samples. The approach consisted of full-length cDNA amplification (acDNA) monitored by real-time PCR, in which the cDNA from half of an oocyte or embryo was used as a template. The GAPDH gene was amplified as a reverse transcription control and samples that were not positive for GAPDH transcripts were discarded. The fold differences between two samples were estimated using delta Ct and statistical analysis and were obtained using the pairwise fixed reallocation randomization test. It was found that the oocytes recovered from grade B COCs had quantitatively less poly(A) mRNA (p< 0.01) transcripts compared with grade A COCs (1 arbitrary unit expression rate). In the comparison with immature oocytes (1 arbitrary unit expression rate), the quantity of poly(A) mRNA did not change during IVM, but declined following IVF and varied with embryo culture (p< 0.05). Amplification of cDNA by real-time PCR was an efficient method to estimate differences in the amount of poly(A) mRNA between oocytes and embryos. The results obtained from individual oocytes suggested an association between poly(A) mRNA abundance and different morphological qualities of oocytes from COCs. In addition, a poly(A) mRNA profile was characterized from oocytes undergoing IVM, fertilization and blastocyst heating.
Development, molecular composition and freeze tolerance of bovine embryos cultured in TCM-199 supplemented with hyaluronan
Authors: Palasz A.T. , Breña P. Beltrán , Martinez Marcelo F. , Perez-Garnelo S.S. , Ramirez M.A. , Gutiérrez-Adán A. , De la Fuente J.
Published: January 2008

Hyaluronan (HA) is glycosaminoglycan that is present from the start of embryonic development and its role and concentration increases with embryo development. The objective of this study was to evaluate if the presence of HA in TCM-199 culture medium had an effect on the development and quality of bovine embryos. There was no effect of HA on the total number of zygotes developing to blastocysts on day 7, however more expanded and hatched blastocyst stages were observed on days 8 and 9 in the group supplemented with HA (p< 0.05). Following freeze/thawing, significantly more (p< 0.05) embryos cultured in medium supplemented with HA hatched than those cultured in TCM-199 alone or those with BSA. Medium supplemented with HA and BSA significantly increased the level of expression of glucose metabolismGlut-1gene and embryo compactionCx43gene (p< 0.05), and had no effect onGlut-5andIGF-IIexpression. In addition, HA presence in culture decreased the level of expression of apoptosisBaxand oxidative stressSOXgenes (p< 0.05). There was significant difference in total number of nuclei between TCM-199 medium only and the remaining media containing BSA or HA plus BSA, between which there was no difference. In summary, our results indicate that the addition of high molecular weight HA to TCM-199 medium that contains BSA on day 4 of culture improved embryo development to hatching and hatched blastocysts and the quality of produced embryos, which were superior to embryos cultured without HA addition.
Viability, acrosome morphology and fertilizing capacity of boar spermatozoa treated with strontium chloride
Authors: Okada Konosuke , Palmieri Chiara , Salda Leonardo Della , Vackova Irena
Published: January 2008

The positive effect of strontium ions (Sr2+) on sperm motility, capacitation and acrosome reaction has been demonstrated in the mouse, human, guinea pig and hamster. In the present study, we have evaluated the effect of Sr2+ on the viability and acrosome morphology of boar spermatozoa, and on the fertilization and development after the microinjection of Sr2+-treated spermatozoa into porcine oocytes. Before incubation, 79% of spermatozoa were classified as propidium iodide (PI)-negative (live) using the LIVE/DEAD Sperm Viability Kit. After incubation with strontium chloride (SrCl2), 39% (0 mM; no divalent cations), 25% (1.9 mM) and 24% (7.5 mM) of them were classified as PI-negative. The proportion of spermatozoa that had initiated the acrosome reaction was higher in Sr2+-containing medium than in Sr2+-free medium, when assessed by electron microscopy. There was no significant difference in percentage of spermatozoa initiating the acrosome reaction between Sr2+-treated groups (1.9 mM: 22%, 7.5 mM: 33%, p > 0.05). After the microinjection of spermatozoa incubated with SrCl2, 67% (1.9 mM) and 61% (7.5 mM) of injected oocytes were successfully fertilized, and then 43% (1.9 mM) and 41% (7.5 mM) contained a fully decondensed sperm head. Sham-injected oocytes were significantly activated at a lower rate than Sr2+-treated groups (27%, p < 0.05). Next, after microinjection of spermatozoa incubated with 1.9 mM SrCl2 (n = 51), 45% of injected oocytes cleaved on day 2, and 18% developed to blastocysts on day 7 (sham-injection, n = 48: 15% to cleavage and 0% to blastocyst). These results demonstrate that Sr2+ is likely to positively affect the fertilizing capacity of spermatozoa in the pig.
5-HT-receptive structures are localized in the interblastomere cleft ofParacеntrotus lividusearly embryos
Authors: Shmukler Yu. B. , Silvestre Francesco , Tosti Elisabetta
Published: January 2008

Local application of the agonists of serotonin receptors of third type 5-HTQ, SR57277A and quipazine into the interblastomere cleft of the sea urchinParacentrotus lividusembryo during first cleavage division, evokes specific membrane currents, whereas application of these drugs out of contact area show currents of lower amplitude and longer latent period. At the same time 5-HT3-receptor agonist quipazine imitates interblastomere signal in half embryos, but corresponding antagonists prevent it. Present data develop the hypothesis of protosynapse, demonstrating that the distribution of membrane serotonin receptors is limited to the period of cleavage division and localized in the interblastomere contact area. A possible role of spatial–temporal restriction of receptors at the interblastomere contact area is discussed in relation to the subsequent embryo development.
Modulators of Bufo arenarum ovulation
Authors: Ramos Inés , Cisint Susana B. , Crespo Claudia A. , Medina Marcela F. , Fernández Silvia N.
Published: January 2008

In this study we investigated ovulation in vitro using ovary samples from Bufo arenarum with respect to their response to stimulation with homologous pituitary homogenate (HPH) or with progesterone and prostaglandins (PGF2α and PGE1) as intermediates of pituitary action. Ovary samples were obtained from animals captured during the breeding period. Our results demonstrate that the ovulatory response to all different inducers was dose dependent, the highest percentage of ovulated oocytes being obtained with HPH treatment. An important increase in the ovulatory response was obtained by the association of PGF2α with either HPH or progesterone at suboptimal doses, indicating that this prostaglandin induced a synergistic potentiating effect. Incubation with cyclooxygenase inhibitors (indomethacin or diclofenac sodium) produced a significant decrease in the ovulation induced by HPH, demonstrating that prostaglandins are involved in the action of the pituitary gland in this process. According to our results, PGE1 not only had no participation in the ovulatory process, but also produced an inhibitory effect on ovulation induced by HPH treatment.
Developmental rate and allocation of transgenic cells in rabbit chimeric embryos
Authors: Chrenek P. , Makarevich A.V. , Bauer M. , Jurcik R.
Published: January 2008

The objective of this study was to compare developmental capacity of rabbit chimeric embryos and the allocation of the EGFP gene expression to the embryoblast (ICM) or embryonic shield. We produced chimeric embryos (TR<>N) by synchronous transfer of two or three blastomeres at the 16-cell stage from transgenic (TR) into normal host embryos (N) at the same stage. In the control group, two to three non-transgenic blastomeres were used to produce chimeric embryos. The TR embryos were produced by microinjection of EGFP into both pronuclei of fertilized rabbit eggs. The developmental rate and allocation of EGFP-positive cells of the reconstructed chimeric embryos was controlled at blastocyst (96 h PC) and embryonic shield (day 6) stage.

All chimeric embryos (120/120, 100%) developed up to blastocyst stage. Using fluorescent microscope, we detected green signal (EGFP expression). In 90 chimeric (TR<>N) embryos (75%). Average total number of cells in chimeric embryos at blastocyst stage was 175 ± 13.10, of which 58 ± 2.76 cells were found in the ICM area. The number of EGFP-positive cells in the ICM area was 24 ± 5.02 (35%). After the transfer of 50 chimeric rabbit embryos at the 16-cell stage, 20 embryos (40%) were flushed from five recipients on day 6 of pregnancy, of which five embryos (25%) were EGFP positive at the embryonic shield stage.

Our results demonstrate that transgenic blastomeres in synchronous chimeric embryos reconstructed from TR embryos have an ability to develop and colonize ICM and embryonic shield area.
Full term development of normal mice after transfer of IVF embryos derived from oocytes stored at room temperature for 1 day
Authors: Lei Zi-Li , Huang Jun-Cheng , Shi Li-Hong , Miao Yi-Liang , Nan Chang-Long , Yang Ji-Wen , OuYang Ying-Chun , Sun Qing-Yuan , Chen Da-Yuan
Published: January 2008

Early studies have shown that some mouse cumulus–oocyte complexes (COCs) stored at room temperature for 24 h still retained full developmental potential. In this study, we stored denuded mouse oocytes (DOs) at room temperature (25 °C) for 24 h and activated these oocytes with 10 mM SrCl2 or fertilized the oocytes by IVF. We found that nearly half of the DOs stored at room temperature for 1 day can be fertilized normally by IVF and that two foster mothers gave birth to seven pups. Embryos from stored oocytes were cultured in CZB medium with or without 1 μg/ml 17β-estradiol (E2). The numbers of embryo that developed to morula/blastocyst stage after parthenogenetic activation and IVF were significantly increased when E2 was added to the culture (p < 0.05). These results suggest that E2 might improve mouse embryo development in vitro. The birth of seven agouti pups and their healthy growth indicated that the storage of DOs at room temperature for 1 day may be a practical procedure for mammalian reproduction.
DISINFLATION AND EXCHANGE-RATE PASS-THROUGH
Authors: SENAY OZGE
Published: January 2008

This paper analyzes exchange-rate dynamics following a money-based disinflation under different degrees of exchange-rate pass-through. Using a microfounded dynamic general equilibrium model with imperfect competition and nominal rigidities, it is shown that a monetary slowdown causes an appreciation of the exchange rate and a short-run fall in employment. Varying the degree of pass-through, however, significantly alters the magnitudes of these effects. As the degree of pass-through is reduced, the extent of the short-run appreciation of the exchange rate increases and the short-run impact of the disinflation on employment falls.
Review of: Tumour invasion and metastasis initiated by microRNA-10b in breast cancer
Authors: Swarbrick Alex
Published: January 2008

Citation of the original article:

L. Ma, J. Teruya-Feldstein, R. A. Weinberg. Nature 2007; 449(7163): 682–688; Epub 26 September 2007.

Abstract of the original article:

MicroRNAs have been implicated in regulating diverse cellular pathways. Although there is emerging evidence that some microRNAs can function as oncogenes or tumour suppressors, the role of microRNAs in mediating cancer metastasis remains unexplored. Here we show, using a combination of mouse and human cells, that microRNA-10b (miR-10b) is highly expressed in metastatic breast cancer cells and positively regulates cell migration and invasion. Overexpression of miR-10b in otherwise non-metastatic breast tumours initiates robust invasion and metastasis. Expression of miR-10b is induced by the transcription factor Twist, which binds directly to the putative promoter of miR-10b (MIRN10B). The miR-10b induced by Twist proceeds to inhibit translation of the messenger RNA encoding homeobox D10, resulting in increased expression of a well-characterized pro-metastatic gene, RhoC. Significantly, the level of miR-10b expression in primary breast carcinomas correlates with clinical progression. These findings suggest the workings of an undescribed regulatory pathway, in which a pleiotropic transcription factor induces expression of a specific microRNA, which suppresses its direct target and in turn activates another pro-metastatic gene, leading to tumour cell invasion and metastasis.
Pre-race warm-up practices in Greyhound racing: a pilot study
Authors: Windred A J , Osmotherly P G , McGowan C M
Published: January 2008

Despite the high athletic demands of Greyhound racing and recommendations for the inclusion of pre-race warm-up by some veterinarians, the extent of warm-up practices by Greyhound owners and trainers remains unexplored. We postulated that little pre-race warm-up occurred and any warm-up activities were performed at random. A cross-sectional study design was used to examine pre-race warm-up practices in a sample of 80 Greyhounds. Warm-up components were recorded and scores were assigned in order to quantify the total amount of warm-up undertaken. Associations between total warm-up and signalment and race characteristics were analysed statistically. Correlations between total warm-up performed and all variables including race distance, race order, grade of Greyhound and trainer were poor (all r < 0.2). No statistically significant association between total warm-up and any variable examined could be demonstrated at the P = 0.05 level, although a weak trend towards graded Greyhounds performing more warm-up was noted (P = 0.09). We conclude that little pre-race warm-up is performed in Greyhounds and that when practised, the amount and methods of warm-up are inconsistently applied.
IMMIGRATION
Authors: Bobo Lawrence D. , Dawson Michael C.
Published: January 2008

There is a deep irony about the current political moment. Though having an immigrant background is arguably a core feature of how most Americans understand themselves, the topic of immigration has in recent years risen to a fever pitch of political controversy and polarized views. Of course, the immigrant streams to the United States today differ substantially from those that characterized the late nineteenth and early twentieth centuries. Instead of bringing in millions of South, Central, and Eastern Europeans looking for better opportunities than were available in their homelands, the current immigrant wave has drawn most heavily from those with Latin American and Asian origins. Concomitant to these changes in economic, cultural, and political context as well as in who constitute the new immigrants, are a series of deep questions about civic belonging, the social consequences of immigration, and what appropriate policy responses to recent immigration should be.
MIGRATION AND SOCIAL STRATIFICATION
Authors: Jaynes Gerald D.
Published: January 2008

The dawn of the twenty-first century confronts Western democracies with a racialized class problem. The globalization of capitalism—mass geographic movement of peoples, capital, and markets on scales unprecedented since the Atlantic slave trade—has brought poor migrants into affluent nations. Migrants' descendants are replicating conditions associated with poor Blacks. Affluent Western democracies are hurtling toward biplural stratification defined by a multiracial underclass. Racialized class stratification stems from economic policies. Capitalist democracies' edifice of social policies—sanctioning expectations of rising prosperity, welfare “safety nets” for minimal consumption, low-wage migration policies—erroneously assumed that jobs and wages would continuously grow to absorb expanding populations. Overuse of low-wage migration policies commodified work relations in low-skilled jobs. Acculturated to demand affluent living standards and egalitarian human relations, educationally deprived descendants of migrants find commodified work regimens repellent. Despite large populations of jobless natives, some maintain that affluent democracies need more migrants to do the jobs that natives won't do. But jobless youth are alienated and prone to agency, as riots in England, the United States, and, more recently, France and other areas of Europe suggest. To avert the solidification of biplural societies, social policy must slow rates of migration from low living-standard economies, expand minimum wages and income transfers to working-citizen households, and provide documented immigrants clear avenues to citizenship. This agenda is more likely to succeed in the United States, where minority voting strength is gathering considerable momentum.
IMMIGRATION AND THE FUTURE OF BLACK POWER IN U.S. CITIES
Authors: Kaufmann Karen M.
Published: January 2008

As a result of urban immigration and White flight over the past three decades, the demography of U.S. cities has changed rather dramatically; approximately one-half of the largest hundred cities are now composed of minority majorities. Many urban scholars expected these demographic shifts to enhance the prospects for minority electoral alliances. In reality, however, few such alliances have emerged. This paper looks to explore the barriers to effective coalition building between native-born African Americans and their immigrant counterparts. In the first half of the paper, I explore the psychological barriers to mass coalitions, focusing on the negative stereotypes and perceived zero-sum conflict that exist between native-born African Americans and Latino immigrants. The second half of the paper argues that material and symbolic incentives fuel ongoing competition between Blacks and Latinos in the political sphere. The paper concludes with a discussion of how immigrant-induced diversity coupled with existing racial hierarchies work against future Black empowerment. Even when changing urban demography makes Whites a numerical minority, White voters often retain their status as urban power players through their ability to divide minority voters at the polls. Divisive electoral strategies that offer political rewards to one group at the expense of others threaten Black incorporation in the urban arena. Unless minority leadership changes the incentive structure embedded in the traditional modes of municipal governance, Whites will persist in their economic dominance, while disadvantaged immigrants and Blacks will continue to make political choices that yield small, short-term rewards at the expense of greater social and economic justice.
BECOMING ETHNIC OR BECOMING AMERICAN?
Authors: Zhou Min , Lee Jennifer
Published: January 2008

As the new second generation comes of age in the twenty-first century, it is making an indelible imprint in cities across the country, compelling immigration scholars to turn their attention to this growing population. In this essay, we first review the extant literature on immigrant incorporation, with a particular focus on the mobility patterns of the new second generation. Second, we critically evaluate the existing assumptions about the definitions of and pathways tosuccessandassimilation. We question the validity and reliability of key measures of social mobility, and also assess the discrepancy between the “objective” measures often used in social science research and the “subjective” measures presented by members of the second generation. Third, we examine the identity choices of the new second generation, focusing on how they choose to identify themselves, and the mechanisms that underlie their choice of identities. We illuminate our review with some preliminary findings from our ongoing qualitative study of 1.5- and second-generation Mexicans, Chinese, and Vietnamese in Los Angeles. In doing so, we attempt to dispel some myths about group-based cultures, stereotypes, and processes of assimilation.
MULTICULTURALISM GOES IMPERIAL
Authors: Kim Claire Jean
Published: January 2008

As Latino and Asian immigrant populations in the United States continue to grow, controversies are cropping up over immigrant animal practices such as horse tripping in Mexicancharreadas(rodeos) and the slaughter of animals in the live-animal markets of San Francisco's Chinatown. Immigrant advocates read these controversies through a multiculturalist interpretive framework that constructs animal advocates as agents of an ethnocentric and racist majority. In this article, I argue that this multiculturalist interpretation tends to “go imperial” by mischaracterizing the position(s) of animal advocates and invalidating and suppressing the other, potentially competitive, moral discourse at play: the discourse about cruelty toward animals. I explicate this suppressed discourse and then propose the development of a mutually challenging and potentially edifying moral dialogue in which majority and minority animal practices are simultaneously open to scrutiny and criticism. Clashes over customary practices can aggravate intergroup tensions, but they also have the potential to lead to meaningful moral dialogue between the majority and immigrant minorities.
MOVING STORIES
Authors: Suárez-Orozco Marcelo , Suárez-Orozco Carola
Published: January 2008

In the first decade of the new millennium, a new cycle of public concern about the benefits and harms of immigration has erupted. The harsh spotlight on undocumented immigration and border controls has blinded us to many important facets of the problem. In this article, we focus on the experience and integration of the children of immigrants. These youth are the largest growing segment of the U.S. child population—now constituting 20% of our nation's children and projected by the year 2040 to make up one-third of our children. Immigrant-origin youth are extraordinarily diverse, and their experiences resist facile generalizations. The social and educational outcomes of immigrant youth will thus vary substantially depending upon the specific constellation of resources and the settlement context. Of critical importance is how immigrant youth fare academically, as this has long-term implications for their future, as well as our society's well-being. While some are successfully navigating the U.S. educational system, large numbers struggle academically, leaving school without having acquired the tools that will enable them to function in the highly competitive labor market and ever more complex society. Here we explore a variety of factors that shed light on the educational integration of the children of immigrants: educational background; poverty; segregation; undocumented status; English-language acquisition; promoting academic engagement; family relations; peer relationships; communities and community organizations; and mentoring relationships. We advocate a major new policy agenda to ease the transition of America's newest and littlest arrivals to their new home.
Influence of turbulence on the shape of a spectral line: the analytical approach
Authors: Silant'ev N. A. , Lekht E. E. , Mendoza-Torres J. E. , Rudnitskij G. M.
Published: January 2008

We consider the propagation of spectral-line radiation in a correlated turbulent atmosphere. The ensembles of turbulent velocities u(r,t) and optical depths, τν, are assumed to be Gaussian. We investigate the explicit analytical solution of the stochastic radiative transfer equation for the intensity Iν of radiation. The scattering term is not taken into account. It is shown that, in addition to the usual Doppler broadening of the spectral line, correlated turbulent motions of atoms and molecules give rise to considerable changes in the shape of a spectral line. We find that the mean intensity I(0)ν (Iν=I(0)ν+I′ν, I′ν = 0) obeys the usual radiative transfer equation with renormalized extinction factor αeffν if the correlation length R0 of the turbulence is small as compared to a photon free path. A simple analytical expression for αeffν is given. This expression integrally depends on the two-point correlation function of the turbulent velocity field.
Short-term variations in Class I methanol masers?
Authors: Pratap Preethi , Strelnitski Vladimir , Hoffman Samantha , Lemonias Jenna
Published: January 2008

Class I methanol masers are found near regions of high-mass star formation and are pumped by collisions. Some indication of long-term variability in these masers has previously been reported (Kurtz et al. 2004). Here we will present evidence for variations in the intensity of the Class I methanol masers at 44 GHz on much shorter timescales. We present preliminary results of the observation of the 44 GHz Class I methanol transition toward sources in the DR21 region that indicates variability on timescales of days to possibly hours.
A review of maser polarization and magnetic fields
Authors: Vlemmings W. H. T.
Published: January 2008

Through polarization observations masers are unique probes of the magnetic field in a variety of different astronomical objects, with the different maser species tracing different physical conditions. In recent years maser polarization observations have provided insights in the magnetic field strength and morphology in, among others, the envelopes around evolved stars, Planetary Nebulae (PNe), massive star forming regions and supernova remnants. More recently, maser observations have even been used to determine the magnetic field in megamaser galaxies. This review will present an overview of maser polarization observations and magnetic field determinations of the last several years and discuss the implications of the magnetic field measurements for several important fields of study, such as aspherical PNe creation and massive star formation.
Magnetic fields in the non-masing ISM
Authors: Crutcher Richard M.
Published: January 2008

Observations of the Zeeman effect in OH and H2O masers provide valuable information about magnetic field strength and direction, but only for the very high density gas in which such masers are found. In order to understand the role of magnetic fields in the evolution of the interstellar medium and in the star formation process, it is essential to consider the maser results in the broader context of magnetic fields in lower density gas. This contribution will (very briefly) summarize the state of observational knowledge of magnetic fields in the non-masing gas. Magnetic fields in H I and molecular clouds may be observed via the Zeeman effect, linear polarization of dust emission, and linear polarization of spectral-line emission. Useful parameters that can be inferred from observations are the mass-to-flux ratio and the scaling of field strength with density. The former tells us whether magnetic fields exert sufficient pressure to provide support against gravitational contraction; the latter tells whether or not magnetic fields are sufficiently strong to determine the nature (spherical or disk geometry) of the contraction. Existing observations will be reviewed. Results are that the strength of interstellar magnetic fields remains roughly invariant at 5-10 microgauss between densities of 0.1 cm−3 < n(H) < 1,000 cm−3 but increases proportional to approximately the square root of density at higher densities. Moreover, the mass-to-flux ratio is significantly subcritical (strong magnetic support with respect to gravity) in diffuse H I clouds that are not self-gravitating, but becomes approximately critical in high-density molecular cloud cores. This suggests that MCs and GMCs form primarily by accumulation of matter along magnetic field lines, a process that will increase density but not magnetic field strength. How clumps in GMCs evolve will then depend crucially on the mass-to-flux ratio in each clump. Present data suggest that magnetic fields play a very significant role in the evolution of molecular clouds and in the star formation process.
VLBI OH maser polarimetry with the Australian Long Baseline Array: the star-forming region G340.054–0.244
Authors: Bains I. , Caswell J. , Richards A. M. S. , Phillips C. , Tingay S. , Kramer B. Hutawarakorn , Cohen R. J. , Cunningham M.
Published: January 2008

Until recently, high spatial resolution full Stokes maser polarimetry was the sole domain of northern interferometers and a wealth of sources in the far south remained unexplored due to a lack of suitable instrumentation having both high spatial and high velocity resolution. The Australia Telescope Long Baseline Array (LBA) has now switched to disk-based software correlation, permitting full Stokes observing in spectral line mode with velocity channels which are sufficiently narrow to sample usefully the polarization structure. To illustrate the utility of this valuable addition to radio astronomy, we present preliminary results of the first such polarimetric observation, the subject of which are the OH masers in the star-forming region G340.054–0.244.
Possible CO clouds interacting with the SNRs G21.8-0.6 and G32.8-0.1
Authors: Zhou Jianjun , Esimbek Jarken , Zhang Xizheng , Zhang Hongbo
Published: January 2008

We have obtained the first CO(1-0) maps towards the SNRs G21.8-0.6 and G32.8-0.1, which are associated with OH 1720 MHz masers. Based on the morphological correspondence between the radio remnant and the CO cloud, and the velocity and position agreement between the OH maser and CO clouds, we tentatively suggest the clouds may be interacting with G21.8-0.6 and G32.8-0.1. However, the shock-excited line broadening was not obvious for these two SNRs. We discuss the possible reasons for this.
Maser science at Tidbinbilla
Authors: Horiuchi Shinji , Lovell Jim
Published: January 2008

The 70 m antenna at Canberra Deep Space Communication Complex (Tidbinbilla) is the largest and most sensitive dish in the southern hemisphere, working at 1, 3, 13 and 18 cm, and as such is in high demand from astronomers both in Australia and overseas. In this paper we present the current status of the single dish spectroscopy system and highlight some recent results in maser science.
Masers and star formation
Authors: Fish Vincent L.
Published: January 2008

Recent observational and theoretical advances concerning astronomical masers in star forming regions are reviewed. Major masing species are considered individually and in combination. Key results are summarized with emphasis on present science and future prospects.
How do methanol masers manage to appear in the youngest star vicinities and isolated molecular clumps?
Authors: Sobolev A. M. , Cragg D. M. , Ellingsen S. P. , Gaylard M. J. , Goedhart S. , Henkel C. , Kirsanova M. S. , Ostrovskii A. B. , Pankratova N. V. , Shelemei O. V. , van der Walt D. J. , Vasyunina T. S. , Voronkov M. A.
Published: January 2008

General characteristics of methanol (CH3OH) maser emission are summarized. It is shown that methanol maser sources are concentrated in the spiral arms. Most of the methanol maser sources from the Perseus arm are associated with embedded stellar clusters and a considerable portion is situated close to compact HII regions. Almost 1/3 of the Perseus Arm sources lie at the edges of optically identified HII regions which means that massive star formation in the Perseus Arm is to a great extent triggered by local phenomena. A multiline analysis of the methanol masers allows us to determine the physical parameters in the regions of maser formation. Maser modelling shows that class II methanol masers can be pumped by the radiation of the warm dust as well as by free-free emission of a hypercompact region (hcHII) with a turnover frequency exceeding 100 GHz. Methanol masers of both classes can reside in the vicinity of hcHIIs. Modelling shows that periodic changes of maser fluxes can be reproduced by variations of the dust temperature by a few percent which may be caused by variations in the brightness of the central young stellar object reflecting the character of the accretion process. Sensitive observations have shown that the masers with low flux densities can still have considerable amplification factors. The analysis of class I maser surveys allows us to identify four distinct regimes that differ by the series of their brightest lines.
Methanol masers as tools to study high-mass star formation
Authors: Pestalozzi Michele R.
Published: January 2008

In this contribution I will attempt to show that the study of Galactic 6.7 and 12.2 GHz methanol masers themselves, as opposed to the use of methanol masers as signposts, can yield important conclusions contributing to the understanding of high-mass star formation. Due to their exclusive association with star formation, methanol masers are the best tools to do this, and their large number allows us to probe the entire Galaxy. In particular I will focus on the determination of the luminosity function of methanol masers and on the determination of an unambiguous signature for a circumstellar masing disc seen edge-on. Finally I will try to point out some future fields of research in the study of methanol masers.
A documentary of high-mass star formation: Probing the dynamical evolution of Orion Source I on 10–100 AU scales using SiO masers
Authors: Matthews L. D. , Goddi C. , Greenhill L. J. , Chandler C. J. , Reid M. J. , Humphreys E. M. L.
Published: January 2008

A comprehensive picture of high-mass star formation has remained elusive, in part because examples of high-mass young stellar objects (YSOs) tend to be relatively distant, deeply embedded, and confused with other emission sources. These factors have impeded dynamical investigations within tens of AU of high-mass YSOs—scales that are critical for probing the interfaces where outflows from accretion disks are launched and collimated. Using observations of SiO masers obtained with the Very Large Array (VLA) and the Very Long Baseline Array (VLBA), the KaLYPSO project is overcoming these limitations by mapping the structure and dynamical/temporal evolution of the material 10-1000 AU from the nearest high-mass YSO: Radio Source I in the Orion BN/KL region. Our data include ~40 epochs of VLBA observations over a several-year period, allowing us to track the proper motions of individual SiO maser spots and to monitor changes in the physical conditions of the emitting material with time. Ultimately these data will provide 3-D maps of the outflow structure over approximately 30% of the outflow crossing time. Here we summarize recent results from the KaLYPSO project, including evidence that high-mass star formation occurs via disk-mediated accretion.
Massive star-formation in G24.78+0.08 studied by means of maser VLBI and thermal interferometric observations
Authors: Moscadelli L. , Goddi C. , Cesaroni R. , Beltràn M. T.
Published: January 2008

This work presents the results of VLBI observations of 6.7 GHz methanol and 22.2 GHz water masers towards the mm core A in the massive star-forming region G24.78+0.08. Comparing the maser with previous millimeter interferometric and recent continuum VLA observations, the physical properties and the gas kinematics of the G24 A core on linear scales from ~100 AU to ~0.1 pc are determined.
A variability study of the H2CO 6cm maser in IRAS 18566+0408
Authors: Araya E. , Hofner P. , Kurtz S. , Linz H. , Sewilo M. , Olmi L. , Watson C.
Published: January 2008

We report the first detection of a short-duration (<3 months) outburst of an H2CO 6cm maser based on multi-epoch observations of IRAS18566+0408 obtained with Arecibo, the Green Bank Telescope, and the Very Large Array. The H2CO maser was observed nine times between 2002 and 2005. In May 2006 we began a two-year program of monthly monitoring with the Arecibo Telescope. The H2CO maser in IRAS18566+0408 is coincident with a young massive stellar object and the line profile of the maser suggests that the H2CO emission originates from two different regions, perhaps associated with the kinematics of a circumstellar disk.
Polarization of 6.0-GHz OH masers in W3(OH)
Authors: Harvey-Smith L. , Soria-Ruiz R. , Richards A. M. S. , Cohen R. J.
Published: January 2008

We present preliminary results of a MERLIN polarization study of 6.0-GHz OH masers in the W3(OH) region of massive star-formation. We have detected a small but significant amount of linear polarization in the 6031-MHz masers, as well as a much larger fraction of circular polarization. We have found many Zeeman pairs, the analysis of which (along with the results at 6035-MHz) will be presented elsewhere. MERLIN is well-suited to detecting all the single-dish maser flux in these regions, owing to its range of short baselines (tens of kilometers) and resulting sensitivity to extended emission. We have found core-halo structure in the 6031-MHz OH maser emission in the region of the highly extended 4.7-GHz OH and 6.7-GHz methanol maser filament found by Harvey-Smith & Cohen (2005, 2006).
LBA observations of OH masers in the star-forming region OH 330.953–0.182
Authors: Kramer B. Hutawarakorn , Caswell J. L. , Sukom A. , Reynolds J. E.
Published: January 2008

OH masers are sensitive probes of the kinematics, physical conditions, and magnetic fields in star-forming regions. The maser site OH 330.953-0.182 has been studied using the Long Baseline Array of the Australia Telescope National Facility. Simultaneous observations of the 1665- and 1667-MHz hydroxyl ground-state transitions yield a series of maps at velocity spacing 0.09kms−1, in both right- and left-hand circular polarization, with tenth-arcsec spatial resolution. Several clusters of maser spots have been detected within a five-arcsec region. Eight Zeeman pairs were found, and in one case, at 1665 MHz, there is a nearby 1667-MHz pair indicating a similar value of magnetic field and velocity. Over the whole site, all magnetic field estimates are toward us (negative), and range from -3.7 to -5.8 mG. We also compared the morphology and kinematics of the 1665- and 1667-MHz maser spots with those from the excited state of OH at 6035 MHz and from methanol at 6668 MHz.