Spectroscopic detections of CIII]1909 at z~6-7: A new probe of early star forming galaxies and cosmic reionisation

Deep spectroscopic observations of z~6.5 galaxies have revealed a marked decline with increasing redshift in the detectability of Lyman-alpha emission. While this may offer valuable insight into the end of the reionisation process, it presents a fundamental challenge to the detailed spectroscopic study of the many hundreds of photometrically-selected distant sources now being found via deep HST imaging, and particularly those bright sources viewed through foreground lensing clusters. In this paper we demonstrate the validity of a new way forward via the convincing detection of an alternative diagnostic line, CIII]1909, seen in spectroscopic exposures of two star forming galaxies at z=6.029 and 7.213. The former detection is based on a 3.5 hour X-shooter spectrum of a bright (J=25.2) gravitationally-lensed galaxy behind the cluster Abell 383. The latter detection is based on a 4.2 hour MOSFIRE spectra of one of the most distant spectroscopically confirmed galaxies, GN-108036, with J=25.2. Both targets were chosen for their continuum brightness and previously-known redshift (based on Lyman-alpha), ensuring that any CIII] emission would be located in a favorable portion of the near-infrared sky spectrum. We compare our CIII] and Lyman-alpha equivalent widths in the context of those found at z~2 from earlier work and discuss the motivation for using lines other than Lyman-alpha to study galaxies in the reionisation era.Comment: 10 pages, 6 figures, submitted to MNRA

Lyman-alpha and CIII] Emission in z=7-9 Galaxies: Accelerated Reionization Around Luminous Star Forming Systems?

We discuss new Keck/MOSFIRE spectroscopic observations of four luminous galaxies at z~7-9 selected to have intense optical line emission by Roberts-Borsani et al. (2016). Previous follow-up has revealed Lyman-alpha in two of the four galaxies. Our new MOSFIRE observations confirm that Lyman-alpha is present in the entire sample. We detect Lyman-alpha emission in COS-zs7-1, confirming its redshift as z=7.154, and we detect Lyman-alpha in EGS-zs8-2 at z=7.477, verifying a tentative detection presented in an earlier study. The ubiquity of Lyman-alpha in this sample is puzzling given that the IGM is likely significantly neutral over 7<z<9. To investigate this result in more detail, we have initiated a campaign to target UV metal emission in the four Lyman-alpha emitters as a probe of both the radiation field and the velocity offset of Lyman-alpha. Here we present the detection of intense CIII] emission in EGS-zs8-1, a galaxy from this sample previously shown to have Lyman-alpha at z=7.73. Photoionization models indicate that an intense radiation field and low metallicity are required to reproduce the intense CIII] and optical line emission. We argue that this extreme radiation field is likely to affect the local environment, increasing the transmission of Lyman-alpha through the galaxy. Moreover, the centroid of CIII] indicates that Lyman-alpha is redshifted from the systemic value by 340 km/s. This velocity offset is larger than that seen in less luminous systems, providing an additional explanation for the transmission of Lyman-alpha emission through the IGM. Since the transmission is further enhanced by the likelihood that such systems are also situated in the densest regions with the largest ionized bubbles, the visibility of Lyman-alpha at z>7 is expected to be strongly luminosity-dependent, with the most effective transmission occurring in systems with intense star formation.Comment: Submitted to MNRAS, 13 pages, 8 figure

A highly solvated zinc(II) tetrakis(pentafluorophenyl)-β-octabromoporphyrin

The title compound, {4,5,9,10,14,15,19,20-octabromo-2,7,12,17-tetrakis(pentafluorophenyl)-21,22,23,- 24-tetraazapentacyclo[16.2.1.1^(3,6).1^(8,11).1^(13,16)]tetracosa-1,3(21),4,6,8(22),9,11,13(23),14,16,18(24),19-dodecaene }zinc(II) (carbon tetrachloride, o-dichlorobenzene, acetone, methanol, water solvate) has a large tetrahedral distortion, with the Br atoms as much as 1.83 Å from the plane of the N atoms. The distortion affects primarily bond angles and bond torsion angles; bond distances in the molecule are normal. Several different solvents are incorporated into the crystal, providing a close (2.16 Å) O atom as an axial neighbor to Zn and a more distant (3.16 Å) Cl atom, in the opposite axial site

Copper(II) and Nickel(II) Octabromo-tetrakis(pentafluorophenyl)Porphyrin Complexes

The copper and nickel complexes of 2,3,7,8,12,13,17, 18-octabromo-5,10,15,20-tetrakis(pentaftuorophenyl) porphyrin ({4,5,9,10,14,15,19,20-octabromo-2,7,12,17-tetrakis(pentaftuorophenyl)-21,22,23,24-tetraazapentacyclo[l6.2.1.1^(3,6).l^(8,11).l^(13,16)]tetracosa-l,3-(22),4,6,8(23),9,11,13(24),14,16,18(21),19-dodecaene }copper(II) 0.5-dichloromethane solvate and {4,5,9,10,14,15,19,20-octabromo-2,7,12,17-tetrakis(pentaftuorophenyl)-21,22,23,24-tetraazapentacyclo( 16.2.1.1^(3,6).l^(8,11).l^(13,16)]tetracosa-l,3(22),4,6,8(23),9,ll,13(24),14,16,18(21),19-dodecaene} nickel(II)0.5-dichloromethane solvate) form isostructural crystals. There is significant distortion from planarity of the porphyrin ring caused by the octabromo substituents interacting with the meso-pentafluorophenyl groups and with each other, with departures of the Br atoms from the plane defined by the four N atoms of up to 2.36 A. This tetrahedral distortion of the molecule does not result in any significant changes in bond distances from those in non-halogenated tetraphenylporphyrin complexes

Copper(II) tetrakis(pentafluorophenyl)-β-octachloroporphyrin

The title compound, {4,5,9,10,14,15,19,20-octachloro-2,7,12, 17-tetrakis(pentafluorophenyl)-20,22,23,24- tetraazapentacyclo[l6.2.l.1^(3·6).l^(8·11).l^(13·16)]tetracosa-1,3(21),4,6,8(22),9,11, 13(23), 14, 16, 18(24), 19-dodecaene}copper(II)(CuTFPPC1_8)dichloromethane solvate, shows a large tetrahedral distortion or ruffling, with pairs of Cl atoms alternately averaging + 1.20 and -1.18 Å out of the plane of the four N atoms; the Cu atom is 0.01 Å out of the plane and the N atoms show a slight (±0.12 Å) tetrahedral distortion. A Cl atom of the solvent, at 3.515 (6) Å in an approximately axial position, is the closest non-bonded neighbor of the Cu atom

Can majority support save an endangered language? A case study of language attitudes in Guernsey

Many studies of minority language revitalisation focus on the attitudes and perceptions of minorities, but not on those of majority group members. This paper discusses the implications of these issues, and presents research into majority andf minority attitudes towards the endangered indigenous vernacular of Guernsey, Channel Islands. The research used a multi-method approach (questionnaire and interview) to obtain attitudinal data from a representative sample of the population that included politicians and civil servants (209 participants). The findings suggested a shift in language ideology away from the post-second world war ‘culture of modernisation’ and monolingual ideal, towards recognition of the value of a bi/trilingual linguistic heritage. Public opinion in Guernsey now seems to support the maintenance of the indigenous language variety, which has led to a degree of official support. The paper then discusses to what extent this ‘attitude shift’ is reflected in linguistic behaviour and in concrete language planning measures

Replication protein A physically interacts with the Bloom's syndrome protein and stimulates its helicase activity.

Bloom's syndrome is a rare autosomal recessive disorder characterized by genomic instability and predisposition to cancer. BLM, the gene defective in Bloom's syndrome, encodes a 159-kDa protein possessing DNA-stimulated ATPase and ATP-dependent DNA helicase activities. We have examined mechanistic aspects of the catalytic functions of purified recombinant BLM protein. Through analyzing the effects of different lengths of DNA cofactor on ATPase activity, we provide evidence to suggest that BLM translocates along single-stranded DNA in a processive manner. The helicase reaction catalyzed by BLM protein was examined as a function of duplex DNA length. We show that BLM catalyzes unwinding of short DNA duplexes (/=259-bp). The presence of the human single-stranded DNA-binding protein (human replication protein A (hRPA)) stimulates the BLM unwinding reaction on the 259-bp partial duplex DNA substrate. Heterologous single-stranded DNA-binding proteins fail to stimulate similarly the helicase activity of BLM protein. This is the first demonstration of a functional interaction between BLM and another protein. Consistent with a functional interaction between hRPA and the BLM helicase, we demonstrate a direct physical interaction between the two proteins mediated by the 70-kDa subunit of RPA. The interactions between BLM and hRPA suggest that the two proteins function together in vivo to unwind DNA duplexes during replication, recombination, or repair

Copper(II) and Nickel(II) Octabromo-tetrakis(pentafluorophenyl)Porphyrin Complexes

The copper and nickel complexes of 2,3,7,8,12,13,17, 18-octabromo-5,10,15,20-tetrakis(pentaftuorophenyl) porphyrin ({4,5,9,10,14,15,19,20-octabromo-2,7,12,17-tetrakis(pentaftuorophenyl)-21,22,23,24-tetraazapentacyclo[l6.2.1.1^(3,6).l^(8,11).l^(13,16)]tetracosa-l,3-(22),4,6,8(23),9,11,13(24),14,16,18(21),19-dodecaene }copper(II) 0.5-dichloromethane solvate and {4,5,9,10,14,15,19,20-octabromo-2,7,12,17-tetrakis(pentaftuorophenyl)-21,22,23,24-tetraazapentacyclo( 16.2.1.1^(3,6).l^(8,11).l^(13,16)]tetracosa-l,3(22),4,6,8(23),9,ll,13(24),14,16,18(21),19-dodecaene} nickel(II)0.5-dichloromethane solvate) form isostructural crystals. There is significant distortion from planarity of the porphyrin ring caused by the octabromo substituents interacting with the meso-pentafluorophenyl groups and with each other, with departures of the Br atoms from the plane defined by the four N atoms of up to 2.36 A. This tetrahedral distortion of the molecule does not result in any significant changes in bond distances from those in non-halogenated tetraphenylporphyrin complexes

Copper(II) tetrakis(pentafluorophenyl)-β-octachloroporphyrin

The title compound, {4,5,9,10,14,15,19,20-octachloro-2,7,12, 17-tetrakis(pentafluorophenyl)-20,22,23,24- tetraazapentacyclo[l6.2.l.1^(3·6).l^(8·11).l^(13·16)]tetracosa-1,3(21),4,6,8(22),9,11, 13(23), 14, 16, 18(24), 19-dodecaene}copper(II)(CuTFPPC1_8)dichloromethane solvate, shows a large tetrahedral distortion or ruffling, with pairs of Cl atoms alternately averaging + 1.20 and -1.18 Å out of the plane of the four N atoms; the Cu atom is 0.01 Å out of the plane and the N atoms show a slight (±0.12 Å) tetrahedral distortion. A Cl atom of the solvent, at 3.515 (6) Å in an approximately axial position, is the closest non-bonded neighbor of the Cu atom

Skeletal Muscle Undergoes Fiber Type Metabolic Switch Without Myosin Heavy Chain Switch in Response to Defective Fatty Acid Oxidation

OBJECTIVE: Skeletal muscle is a heterogeneous and dynamic tissue that adapts to functional demands and substrate availability by modulating muscle fiber size and type. The concept of muscle fiber type relates to its contractile (slow or fast) and metabolic (glycolytic or oxidative) properties. Here, we tested whether disruptions in muscle oxidative catabolism are sufficient to prompt parallel adaptations in energetics and contractile protein composition. METHODS: Mice with defective mitochondrial long-chain fatty acid oxidation (mLCFAO) in the skeletal muscle due to loss of carnitine palmitoyltransferase 2 (Cpt2(Sk−/−)) were used to model a shift in muscle macronutrient catabolism. Glycolytic and oxidative muscles of Cpt2(Sk−/−) mice and control littermates were compared for the expression of energy metabolism-related proteins, mitochondrial respiratory capacity, and myosin heavy chain isoform composition. RESULTS: Differences in bioenergetics and macronutrient utilization in response to energy demands between control muscles were intrinsic to the mitochondria, allowing for a clear distinction of muscle types. Loss of CPT2 ablated mLCFAO and resulted in mitochondrial biogenesis occurring most predominantly in oxidative muscle fibers. The metabolism-related proteomic signature of Cpt2(Sk−/−) oxidative muscle more closely resembled that of glycolytic muscle than of control oxidative muscle. Respectively, intrinsic substrate-supported mitochondrial respiration of CPT2 deficient oxidative muscles shifted to closely match that of glycolytic muscles. Despite this shift in mitochondrial metabolism, CPT2 deletion did not result in contractile-based fiber type switching according to myosin heavy chain composition analysis. CONCLUSION: The loss of mitochondrial long-chain fatty acid oxidation elicits an adaptive response involving conversion of oxidative muscle toward a metabolic profile that resembles a glycolytic muscle, but this is not accompanied by changes in myosin heavy chain isoforms. These data suggest that shifts in muscle catabolism are not sufficient to drive shifts in the contractile apparatus but are sufficient to drive adaptive changes in metabolic properties