A Volcanic Origin for Sinuous and Branching Channels on Mars: Evidence from Hawaiian Analogs

Observations of sinuous and branching channels on planets have long driven a debate about their origin, fluvial or volcanic processes. In some cases planetary conditions rule out fluvial activity (e.g. the Moon, Venus, Mercury). However, the geology of Mars leads to suggestions that liquid water existed on the surface in the past. As a result, some sinuous and branching channels on Mars are cited as evidence of fluvial erosion. Evidence for a fluvial history often focuses on channel morphologies that are unique from a typical lava channel, for instance, a lack of detectable flow margins and levees, islands and terraces. Although these features are typical, they are not necessarily diagnostic of a fluvial system. We conducted field studies in Hawaii to characterize similar features in lava flows to better define which characteristics might be diagnostic of fluvial or volcanic processes. Our martian example is a channel system that originates in the Ascraeus Mons SW rift zone from a fissure. The channel extends for approx.300 km to the SE/E. The proximal channel displays multiple branches, islands, terraces, and has no detectable levees or margins. We conducted field work on the 1859 and 1907 Mauna Loa flows, and the Pohue Bay flow. The 51-km-long 1859 Flow originates from a fissure and is an example of a paired a a and pahoehoe lava flow. We collected DGPS data across a 500 m long island. Here, the channel diverted around a pre-existing obstruction in the channel, building vertical walls up to 9 m in height above the current channel floor. The complicated emplacement history along this channel section, including an initial a a stage partially covered by pahoehoe overflows, resulted in an appearance of terraced channel walls, no levees and diffuse flow margins. The 1907 Mauna Loa flow extends > 20 km from the SW rift zone. The distal flow formed an a a channel. However the proximal flow field comprises a sheet that experienced drainage and sagging of the crust following the eruption. The lateral margins of the proximal sheet, past which all lava flowed to feed the extensive channel, currently display a thickness of < 20 cm. Were this area covered by a dust layer, as is the Tharsis region on Mars, the margins would be difficult to identify. The Pohue Bay flow forms a lava tube. Open roof sections experienced episodes of overflow and spill out. In several places the resultant surface flows appear to have moved as sheet flows that inundated the preexisting meter scale features. Here the flows developed pathways around topographic highs, and in so doing accreted lava onto those features. The results are small islands within the multiple branched channels that display steep, sometimes overhanging walls. None of these features alone proves that the martian channel networks are the result of volcanic processes, but analog studies such as these are the first step towards identifying which morphologies are truly diagnostic of fluvial and volcanic channels

A relativistically covariant version of Bohm's quantum field theory for the scalar field

We give a relativistically covariant, wave-functional formulation of Bohm's quantum field theory for the scalar field based on a general foliation of space-time by space-like hypersurfaces. The wave functional, which guides the evolution of the field, is space-time-foliation independent but the field itself is not. Hence, in order to have a theory in which the field may be considered a beable, some extra rule must be given to determine the foliation. We suggest one such rule based on the eigen vectors of the energy-momentum tensor of the field itself.Comment: 1 figure. Submitted to J Phys A. 20/05/04 replacement has additional references and a few minor changes made for clarity. Accepted by J Phys

Volcanic or Fluvial Channels on Ascraeus Mons: Focus on the Source Area of Sinuous Channels on the Southeast Rift Apron

Deciphering the Mars water history is important to understanding the planet's geological evolution and whether it could have sustained life. Channel features on Mars, such as the features documented in Kasei Valles, are generally accepted as evidence for water flowing over the Mars surface in the past [1]. However, not all channels are the product of fluvial processes and many can be interpreted as having a volcanic origin [2]. This research involves studying channel features on the flanks of the Ascraeus Mons volcano, which is a part of the Tharsis province. Numerous sinuous channels exist on the rift apron of Ascraeus Mons and they have been interpreted as either fluvial [3] or volcanic [4,5]. The channels originate from pits and linear depressions and extend for many 100 s of km downslope. Mapping the proximal to distal morphology of the complete channel and determining its relationship with other features on the apron provides evidence for the processes of formation and their relative temporal relationships. This study focused on sinuous channels located on the south-east part of the Ascraeus rift apron (Fig. 1). Observations of possible analogous features on Hawaii are used to provide insights into the processes of formation of the Mars features

Gene transfer into hepatocytes using asialoglycoprotein receptor mediated endocytosis of DNA complexed with an artificial tetra-antennary galactose ligand

We have constructed an artificial ligand for the hepatocyte-specific asialoglycoprotein receptor for the purpose of generating a synthetic delivery system for DNA. This ligand has a tetra-antennary structure, containing four terminal galactose residues on a branched carrier peptide. The carbohydrate residues of this glycopeptide were introduced by reductive coupling of lactose to the alpha- and epsilon-amino groups of the two N-terminal lysines on the carrier peptide. The C-terminus of the peptide, containing a cysteine separated from the branched N-terminus by a 10 amino acid spacer sequence, was used for conjugation to 3-(2-pyridyldithio)propionate-modified polylysine via disulfide bond formation. Complexes containing plasmid DNA bound to these galactose-polylysine conjugates have been used for asialoglycoprotein receptor-mediated transfer of a luciferase gene into human (HepG2) and murine (BNL CL.2) hepatocyte cell lines. Gene transfer was strongly promoted when amphipathic peptides with pH-controlled membrane-disruption activity, derived from the N-terminal sequence of influenza virus hemagglutinin HA-2, were also present in these DNA complexes. Thus, we have essentially borrowed the small functional domains of two large proteins, asialoglycoprotein and hemagglutinin, and assembled them into a supramolecular complex to generate an efficient gene-transfer system

Destination Substitution and Social Networks among Urban Refugees in Kampala, Uganda

A significant number of refugees and asylum seekers live in Kampala as opposed to the rural settlement areas. However, what is less known is the extent of destination substitution among these refugees and factors associated with changes in destination. Using a survey of 479 refugees from eight nationalities, this study examined the influences of social networks on destination substitution among refugees in Kampala. It was found that more than half of the refugees substituted their initially intended destination with Kampala.&nbsp; Refugees with social network ties in Kampala are likely to substitute their preferred destination for Kampala compared to those who do not have social network ties in Kampala. The study contributes to the literature on destination choices and social networks by showing that the refugees have destination preferences, but these preferences can be constrained by prevailing circumstances. Facilitated by social networks with alternative destinations, refugees may substitute their preferred destinations with a proxy destination in cities in neighboring countries

Developing a generic network planning interface

Please read the abstract in the section 00front of this documentDissertation (MSc (Computer Science))--University of Pretoria, 2007.Computer Scienceunrestricte

Vuvuzela sound measurements

We recently published a scientific letter in the South African Medical Journal reporting the maximum output levels of a Vuvuzela. The publication has drawn varied reactions from the media and other interested parties. In response to enquiries the additional information on the method and results reported in the earlier paper is provided

State patients who committed violent crimes and were admitted to Weskoppies Hospital from 2005 to 2014 : profiles and trends

BACKGROUND : Most of the available literature focus on characteristics of violent offenders and trends of crime patterns in the general population. The crime trends in the population of those who may be mentally ill have not been well described. AIM : To describe the profiles and trends of mentally ill persons who committed violent crimes prior to admission as state patients. SETTING : The study was conducted at Weskoppies Psychiatric Hospital. METHOD : A retrospective record review of state patients admitted between 2005 and 2014 was conducted to describe demographic, clinical, forensic and victim profiles of state patients admitted from 2005 to 2014. Trends over time were also assessed. RESULTS : Hundred and seventy state patient files were reviewed. The majority were males (91.43%), with a history of substance use (55.0%) %), previous psychiatric treatment (46.4%), and diagnosed with a psychotic disorder (82.1%). The 10 year trend showed that murder was the leading charge during 2006 and 2007. It was surpassed by sexual assault crimes as the most common charge after 2007, except for 2009 when murder was again the most common. From 2010 onward, sexual assault remained the most common offence leading to admission as a state patient. CONCLUSION : This study found changes over time in crime patterns of state patients who committed murder and sexual assault. State patients may have different criminal patterns than the general public. This together with the high rates of substance use and previous psychiatric treatment can be important focus areas for future research.http://www.sajpsychiatry.orgam2021Psychiatr

Herbivory-induced reduction in photosynthetic productivity of water hyacinth, Eichhornia crassipes (Martius) Solms-Laubach (Pontederiaceae), is not directly related to reduction in photosynthetic leaf areas

The purpose of this investigation was to determine whether the reduced photosynthetic productivity of water hyacinth plants subject to N. eichhorniae adult feeding was simply the result of reduced leaf area, or if more complex mechanisms were involved