Nuevo conocimiento - NAT

URI permanente para esta colecciónhttp://hdl.handle.net/10906/78210

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2-Bromo-N-(2-hy-droxy-5-methyl-phen-yl)-2-methyl-propanamide.
(International Union of Crystallography, 2011-09-01) Grande Tovar, Carlos
In the title mol-ecule, C(11)H(14)BrNO(2), there is twist between the mean plane of the amide group and the benzene ring [the C-N-C-C torsion angle is -172.1 (2)°]. The amide H atom forms an intra-molecular hydrogen bond with the Br atom. In the crystal, inter-molecular O-H⋯O and weak C-H⋯O hydrogen bonds link mol-ecules into a chain along [100].
A ‘slow pace of life’ in Australian old-endemic passerine birds is not accompanied by low basal metabolic rates
(Springer Verlag, 2016-05-01) Buttemer, William A.
Life history theory suggests that species experiencing high extrinsic mortality rates allocate more resources toward reproduction relative to self-maintenance and reach maturity earlier (‘fast pace of life’) than those having greater life expectancy and reproducing at a lower rate (‘slow pace of life’). Among birds, many studies have shown that tropical species have a slower pace of life than temperate-breeding species. The pace of life has been hypothesized to affect metabolism and, as predicted, tropical birds have lower basal metabolic rates (BMR) than temperate-breeding birds. However, many temperate-breeding Australian passerines belong to lineages that evolved in Australia and share ‘slow’ life-history traits that are typical of tropical birds. We obtained BMR from 30 of these ‘old-endemics’ and ten sympatric species of more recently arrived passerine lineages (derived from Afro-Asian origins or introduced by Europeans) with ‘faster’ life histories. The BMR of ‘slow’ temperate-breeding old-endemics was indistinguishable from that of new-arrivals and was not lower than the BMR of ‘fast’ temperate-breeding non-Australian passerines. Old-endemics had substantially smaller clutches and longer maximal life spans in the wild than new arrivals, but neither clutch size nor maximum life span was correlated with BMR. Our results suggest that low BMR in tropical birds is not functionally linked to their ‘slow pace of life’ and instead may be a consequence of differences in annual thermal conditions experienced by tropical versus temperate species. © 2016, Springer-Verlag Berlin Heidelberg.
Activity of (2E)-3-(2, 3-dimetoxifenil)-1-(4-metilfenil) prop-2-en-1-ona in the presence of poli(maleic acid-co-2-vinyl-pyrrolidone) on a β-lactamase producing clinical isolate of Staphylococcus aureus
(Universidad de Antioquia, 2012-01-01) Salamanca Mejía, Constaín Hugo
Due to the current problem of resistance to b-lactam antibiotics, it has become necessary, in search of a solution, to work with new molecules with pharmacological potential, and to use novel polymeric systems as matrices or pharmaceutical excipients. Objective: To evaluate the antibiotic activity of ampicillin combined with a synthetic chalcone-type compound, the (2E)-3-(2,3-dimethoxyphenyl)-1-(4- methylphenyl) prop-2-en-1-one, on a clinical isolate of penicillin-resistant Staphylococcus aureus in the presence of a water soluble polymer matrix known as poly(maleic acid-co-2-vinyl-pyrrolidone). Materials and methods: The synthetic compound and the polymeric matrix were obtained by previously described methods. Tests for antibiotic activity against the strain of penicillin-resistant Staphylococcus aureus were done by the broth dilution technique which provided the minimal inhibitory concentrations of the compounds tested. Results: The chalcone-ampicillin mix shows lesser antibiotic effect than the ampicillin-sulbactam used as referent. However, when such mix is combined with the polymer matrix, antibiotic activity significantly increases as evidenced by decrease in the minimal inhibitory concentration with respect to the ampicillin-sulbactam referent.
Acyclic diene metathesis polymerization: History, methods and applications
(Elsevier Ltd, 2017-06-01) Caire da Silva, Lucas
Acyclic Diene Metathesis (ADMET) polymerization was established decades ago and has since developed into a robust and reliable technique. A wide range of different, new materials exhibiting unique properties has been produced via ADMET polymerization since its development. This versatile technique allows, through the right combination of monomer design and choice of catalyst, the synthesis of various functional polymers in addition to a precise control over primary structure. Systematic studies on precise ADMET polymers have greatly contributed to a better understanding of how branch identity and its distribution along the polymer backbone affect the thermal/electronic properties, crystallization, molecular dynamics and morphology of different materials. This article presents an extensive review of how ADMET started, the mechanism that underlies the structural features of ADMET polymers and the different strategies and techniques that have been developed over the years to overcome common synthetic challenges. Monomer synthesis methods are also discussed in detail, providing an important overview of the limitations and advantages of using ADMET as a polymerization technique. Many examples are given of functional ADMET polymers that have been developed by research groups all over the world. © 2016 Elsevier B.V.
Additive partitioning of spider diversity in a fragmented tropical dry forest (Valle del Cauca, Colombia)
(American Arachnological Society, 2010-01-01) Cabra García, Jimmy
Abstract Understanding the variation of diversity patterns requires analysis at multiple spatial scales. In this study we estimated the diversity components (alpha, beta and gamma) of the spider community at El Vínculo Natural Regional Park, using the additive partitioning of diversity (species richness, Shannon's diversity index and Simpson's index) for the first time on this taxon in Colombia. We collected the specimens following a nested sampling design that consisted of two spatial scales. At the local scale, we quantified additive diversity components in 238 sampling units, and at the regional scale in five vegetation types. Total observed regional diversity (γ) was partitioned into its additive components: within sampling units (α1), among sampling units (βl) and among vegetation types (β2). We used the same approach to compare common and infrequent spider species and to compare sampling methods. A total of 1565 adult spiders and 72 identifiable juveniles, including 193 morphospecies from 36 familie.
AFLP and MS-AFLP Analysis of the Variation within Saffron Crocus (Crocus sativus L.) Germplasm
(Public Library of Science, 2015-04-17) Santaella Tenorio, Marcela
The presence and extent of genetic variation in saffron crocus are still debated, as testified by several contradictory articles providing contrasting results about the monomorphism or less of the species. Remarkably, phenotypic variations have been frequently observed in the field, such variations are usually unstable and can change from one growing season to another. Considering that gene expression can be influenced both by genetic and epigenetic changes, epigenetics could be a plausible cause of the alternative phenotypes. In order to obtain new insights into this issue, we carried out a molecular marker analysis of 112 accessions from theWorld Saffron and Crocus Collection. The accessions were grown for at least three years in the same open field conditions. The same samples were analysed using Amplified Fragment Length Polymorphism (AFLP) and Methyl Sensitive AFLP in order to search for variation at the genetic (DNA sequence) and epigenetic (cytosine methylation) level. While the genetic variability was low (4.23% polymorphic peaks and twelve (12) effective different genotypes), the methyl sensitive analysis showed the presence of high epigenetic variability (33.57% polymorphic peaks and twenty eight (28) different effective epigenotypes)
Aggregates of alternate amphiphilc polyanion to carry zwitterionic drug in aquedous media
(2015-06-01) Quintero, Andrés
The effect of amphiphilic polyanion Poly(maleic acid-alt-octadecene)sodium salt on solubility of a zwitterionic drug (ampicillin trihydrate) in aqueous media was evaluated. This polymeric salt was obtained by an equimolar reaction of parent copolymer poly Poly(maleic acid-alt-octadecene)with an aqueous solution of NaOH. The obtained amphiphilic polyanion was purified by dialysis and lyophilization and was characterized by FTIR spectroscopy. Secondly, a method for the model drug quantification by UV spectrophotometry at 37°C was standardized. Also the grade of association drug-polymer in aqueous media using ultrafiltration methodology at three levels of temperature (20, 30 and 40°C) and two levels of pH (1.2 and 7.4) was determined. Finally, the variation of aqueous solubility of ampicillin trihydrate in ultra-pure water and two buffer media with pH of 1.2 and 7.4 with an ionic strength of 0.15 M at 37°C in presence and absence of amphiphilic polyanion was evaluated. It was found that maximum solubility is reached at a pH value of 1.2 in absence of polymeric material with a value of 36 mg/mL, which diminishes dramatically to a value of 8.3mg/mL when the polyanion is added. In the other side, when the system has a pH value of 7.4, the drug solubility slightly increases from 13 to 16mg/mL in presence of polymeric material, describing that solubility of this kind of drugs is strongly influenced by aqueous media and this type of polymeric materials.
Amyloid-β precursor protein modulates the sorting of testican-1 and contributes to its accumulation in brain tissue and cerebrospinal fluid from patients with Alzheimer disease
(Lippincott Williams and Wilkins, 2016-01-01) Ferrer, Isidre Sidre
The mechanisms leading to amyloid-β (Aβ) accumulation in sporadic Alzheimer disease (AD) are unknown but both increased production or impaired clearance likely contribute to aggregation. To understand the potential roles of the extracellular matrix proteoglycan Testican-1 in the pathophysiology of AD, we used samples from AD patients and controls and an in vitro approach. Protein expression analysis showed increased levels of Testican-1 in frontal and temporal cortex of AD patients; histological analysis showed that Testican-1 accumulates and co-aggregates with Aβ plaques in the frontal, temporal and entorhinal cortices of AD patients. Proteomic analysis identified 10 fragments of Testican-1 in cerebrospinal fluid (CSF) from AD patients. HEK293T cells expressing human wild type or mutant Aβ precursor protein (APP) were transfected with Testican-1. The co-expression of both proteins modified the sorting of Testican-1 into the endocytic pathway leading to its transient accumulation in Golgi, which seemed to affect APP processing, as indicated by reduced Aβ40 and Aβ42 levels in APP mutant cells. In conclusion, patient data reflect a clearance impairment that may favor Aβ accumulation in AD brains and our in vitro model supports the notion that the interaction between APP and Testican-1 may be a key step in the production and aggregation of Aβ species. © 2016 Oxford University Press OR American Association of Neuropathologists.
Analytical optimal pulse shapes obtained with the aid of genetic algorithms
(American Institute of Physics Inc., 2015-09-28) Reyes, Andrés
We propose a methodology to design optimal pulses for achieving quantum optimal control on molecular systems. Our approach constrains pulse shapes to linear combinations of a fixed number of experimentally relevant pulse functions. Quantum optimal control is obtained by maximizing a multi-target fitness function using genetic algorithms. As a first application of the methodology, we generated an optimal pulse that successfully maximized the yield on a selected dissociation channel of a diatomic molecule. Our pulse is obtained as a linear combination of linearly chirped pulse functions. Data recorded along the evolution of the genetic algorithm contained important information regarding the interplay between radiative and diabatic processes. We performed a principal component analysis on these data to retrieve the most relevant processes along the optimal path. Our proposed methodology could be useful for performing quantum optimal control on more complex systems by employing a wider variety of pulse shape functions. © 2015 AIP Publishing LLC.
AngiomiRs: Potential Biomarkers of Pregnancy's Vascular Pathologies
(Hindawi Publishing Corporation, 2015-01-01) Forero, Jose Vicente Forero
In recent years, microRNAs (miRNAs) have been the focus of research for their role in posttranscriptional regulation and as potential biomarkers of risk for disease development. Their identification in specific physiological processes, like angiogenesis, a key pathway in placental vascular development in pregnancy, suggests an important role of miRNAs that regulate angiogenesis (angiomiRs). Many complications of pregnancy have in common placental vascular alterations, involving an imbalance in the angiogenesis process in the development of conditions such as preeclampsia, intrauterine growth restriction, and gestational diabetes, complications with the highest rates of morbimortality in pregnancy. Many studies have identified angiomiRs with differential expression profiles in each of these diseases; however, this evidence requires further studies focused on evaluating their potential as biomarkers of risk for the angiomiRs detected, to establish correlations between placental tissue and serum/plasma expression profiles. Therefore, the objective of this review is to highlight the best angiomiRs detected in placental tissue and serum/plasma in each of these three pathologies to show the current data available for potential biomarkers and to propose future research strategies on this topic. © 2015 Laura María Rodríguez Santa et al.
Assessment of genetic diversity in Venezuelan rice cultivars using simple sequence repeats markers
(Pontificia Universidad Católica de Valparaíso, 2008-01-01) Ghneim Herrera, Thaura
In Venezuela, pedigree analyses indicate that the rice varieties currently under cultivation are closely related. Effective breeding programs, based on knowledge of the genetic diversity of cultivars, are needed to broaden the genetic bases of rice germplasm in the country. In this study, we used a set of 48 simple-sequence-repeat (SSR) markers to assess the genetic diversity of 11 Venezuelan rice cultivars, released by the National Rice Breeding Program between 1978 and 2007. A total of 203 alleles were detected, the number of alleles ( NA ) per marker ranged from 2 to 9, with an average of 4.23. The average genic diversity ( H ) over all SSR loci for the 18 genotypes was 0.524, ranging from 0.105 to 0.815. Positive correlations were found between H at each locus, NA , the allele size range and the maximum number of repeats. Venezuelan cultivars showed lower H (mean = 0.37) and NA (total = 124, mean = 2.58) than the whole sample. UPGMA-cluster-analysis based on genetic distance coefficients clearly separated all the genotypes , and showed that the Venezuelan rice varieties are closely related. Molecular identification of 7 Venezuelan cultivars could be done with 9 primers pairs which produced 10 genotype-specific-alleles. Although the genetic diversity was low, SSRs proved to be an efficient tool in assessing the genetic diversity of rice genotypes. Implications of the low genetic diversity detected and relatedness of Venezuelan cultivars are discussed.
Atherosclerosis development in SLE patients is not determined by monocytes ability to bind/endocytose Ox-LDL.
(2011-06-14) Montoya Peláez, Guillermo León
Patients with systemic lupus erythematosus (SLE) have a high risk of developing cardiovascular disease; however, the mechanisms involved in the early onset of atherosclerosis in these patients are not clear. Scavenger receptors, CD36 and CD163 are expressed by mononuclear phagocytes and participate in the binding and uptake of oxidized low-density lipoproteins (Ox-LDL), contributing to foam-cells formation and atherosclerosis development. The aim of the present study was to evaluate CD36(+) and CD163(+) expression and Ox-LDL removal by monocytes from SLE and atherosclerotic patients, compared to similar age-range healthy controls. Healthy controls, SLE, and atherosclerotic patients were evaluated for carotid intima media thickness (CIMT), lipid profile, and native LDL (N-LDL) and Ox-LDL binding/endocytosis. SLE patients presented decreased high-density lipoproteins (HDL) and increased Triglyceride levels, and half of the SLE patients had increased CIMT, compared to their healthy controls (HC(SLE)). The number of CD14(+)CD163(+) cells was increased in atherosclerosis healthy controls (HC(Atheros)) compared to HC(SLE), but there were no differences between SLE or atherosclerotic patients and their respective healthy controls. Clearance assays revealed a similar capacity to bind/endocytose Ox-LDL by monocytes from SLE patients and HC(SLE), and an increased binding and endocytosis of Ox-LDL by monocytes from atherosclerotic patients, compared to HC(Atheros). The decreased CD36 and CD163 expression observed in atherosclerotic and SLE patients, respectively, suggest that these inflammatory conditions modulate these receptors differentially. The increased CIMT observed in SLE patients cannot be explained by Ox-LDL binding/endocytosis, which was comparable to their controls.
Atorvastatin protects GABAergic and dopaminergic neurons in the nigrostriatal system in an experimental rat model of transient focal cerebral ischemia.
(2014-01-01) Arango Mambuscay, Carlos Alberto
Cerebral ischemia is the third leading cause of death and the primary cause of permanent disability worldwide. Atorvastatin is a promising drug with neuroprotective effects that may be useful for the treatment of stroke. However, the effects of atorvastatin on specific neuronal populations within the nigrostriatal system following cerebral ischemia are unknown. OBJECTIVE To evaluate the effects of atorvastatin on dopaminergic and GABAergic neuronal populations in exofocal brain regions in a model of transient occlusion of the middle cerebral artery. MATERIALS AND METHODS Twenty-eight male eight-week-old Wistar rats were used in this study. Both sham and ischemic rats were treated with atorvastatin (10 mg/kg) or carboxymethylcellulose (placebo) by gavage at 6, 24, 48 and 72 hours post-reperfusion. We analyzed the immunoreactivity of glutamic acid decarboxylase and tyrosine hydroxylase in the globus pallidus, caudate putamen and substantia nigra. RESULTS We observed neurological damage and cell loss in the caudate putamen following ischemia. We also found an increase in tyrosine hydroxylase immunoreactivity in the medial globus pallidus and substantia nigra reticulata, as well as a decrease in glutamic acid decarboxylase immunoreactivity in the lateral globus pallidus in ischemic animals treated with a placebo. However, atorvastatin treatment was able to reverse these effects, significantly decreasing tyrosine hydroxylase levels in the medial globus pallidus and substantia nigra reticulata and significantly increasing glutamic acid decarboxylase levels in the lateral globus pallidus. CONCLUSION Our data suggest that post-ischemia treatment with atorvastatin can have neuro-protective effects in exofocal regions far from the ischemic core by modulating the GABAergic and dopaminergic neuronal populations in the nigrostriatal system, which could be useful for preventing neurological disorders.
Basal metabolism in tropical birds: latitude, altitude, and the ‘pace of life’
(Wiley, 2015-03-01) Londoño, Gustavo Adolfo
Life history varies across latitudes, with the ‘pace of life’ being ‘slower’ in tropical regions. Because life history is coupled to energy metabolism via allocation tradeoffs and links between performance capacity and energy use, low metabolic intensity is expected in tropical animals. Low metabolism has been reported for lowland tropical birds, but it is unclear if this is due to ‘slow’ life history or to a warm, stable environment. We measured basal metabolic rates (BMR) of 253 bird species across a 2·6 km altitude gradient in Peru. We predicted higher BMR at high altitude due to lower temperatures leading to elevated thermoregulatory costs. We also tested for BMR differences between widely separated tropical regions (Peru and Panama), and between tropical- and temperate-breeding birds.
Los bosques secos del Valle del Cauca, Colombia: una aproximación a su flora actual
(Universidad Nacional de Colombia, 2012-12-01) Vargas, William Gerardo
From the plant collections and personal records made by the author in the dry forests of Valle del Cauca between 1992 and 2012, presents an analysis of current status of the flora and dry forests in the region. After reviewing nearly 12.000 records of herbal plants Valley dry forests and explored the key areas, the current membership consists of approximately 1.300 species of vascular plants, of which 255 correspond to trees. Epiphytes and trees are the groups most affected by deforestation, and on which it is possible to better understand how they have impacted natural ecosystems in Valle del Cauca, is also on them that can more effectively focus conservation actions that generate a positive impact. It also presents a list of 936 plant species of the dry forests, the largest so far presented, and which contains information on habits, distribution, abundance, threats, habitat and type of dispersion. This work aims to contribute to knowledge and design of strategies for conservation and restoration of these ecosystems.
Breeding biology and egg temperatures of Black-faced Brush-finches (Atlapetes melanolaemus), Neotropical montane songbirds
(Blackwell Publishing Inc., 2016-01-01) Londoño Guerrero, Gustavo Adolfo
Black-faced Brush-finches (Atlapetes melanolaemus) are a common species restricted to the Andes of southern Peru and western Bolivia. We provide the first description of the breeding biology of this Neotropical montane passerine, including an analysis of incubation behavior and egg temperatures. We found 47 nests during seven breeding seasons (2007–2013) near Manu National Park, Peru. Nesting occurred in late July, peaked in early October, and continued into early December. All clutches consisted of two eggs, and the mean incubation period (14.8 ± 0.2 d) was relatively short compared with related species. Nest attentiveness increased and the length of foraging trips decreased as the incubation period progressed, but the number of foraging trips/day was constant. Egg temperatures when birds returned to incubate were negatively correlated with the duration of incubation bouts, whereas ambient temperature and the duration of the previous incubation bout were positively correlated with the duration of foraging bouts. Eggs were consistently incubated at lower temperatures (24-h mean = 32.1°C) than other Neotropical and temperate species. When incubating birds left nests, egg temperature dropped below the physiological zero temperature (24–27°C) in ~11 min. Nestlings had a high growth rate (k = 0.60) and a long nestling period (mean = 13.8 d) compared with related Neotropical and temperate emberizines. By showing that the duration of incubation and foraging bouts are affected by different intrinsic and extrinsic factors, we provide evidence that incubation is not only temporally dynamic, but also finely modifiable. Our results also suggest that embryos of high-elevation Neotropical songbirds are particularly resistant to ambient temperature extremes and low incubation temperatures, emphasizing the need for more studies of egg thermoregulation and its consequences for development, growth, and survival. We conclude that closely related species, both on different continents and at the same locations, may differ in parental care strategies and development regimes, cautioning against broad generalizations regarding species groups or geographic areas. © 2016 Association of Field Ornithologists
Brood parasitism by the enigmatic and rare Pavonine Cuckoo in Amazonian Peru
(American Ornithological Society, 2017-04-01) Sánchez Martínez, Manuel A.
Brood parasitism is an uncommon and understudied strategy in Amazonian bird communities, within which only 5 species are known to be brood parasites. We present data on the brood-parasitic behavior of the Pavonine Cuckoo (Dromococcyx pavoninus) in 3 host species of small-bodied flycatchers in the Peruvian Amazon that construct hanging globular nests with side entrances. During the 7 yr of the study, we encountered 74 nests of these 3 hosts, but parasitism occurred only in 9 nests (12.2%) in 2 yr. Only 1 Pavonine Cuckoo egg was deposited in each host nest (n = 7), and eggs were markedly dissimilar in size and coloration between hosts and parasite. Incubation investment per day was slightly higher (4%) for 1 parasitized nest than for nonparasitized nests. Overall, 33% of parasitic eggs (n = 6) hatched; cuckoo nestlings apparently removed host eggs and killed host nestlings. The nestling period lasted 24 days, and the growth-rate constant based on nestling mass (k = 0.23) was slower for parasite nestlings than for their hosts (k = 0.27 and 0.31). Food provisioning rates were greater in 1 parasitized nest (2.1 ± 0.7 feedings hr-1 nestling-1) than in nonparasitized nests (1.1 ± 0.4). Nestling cuckoos may further mimic the plumage of their host nestlings. Our results suggest that Pavonine Cuckoos negatively affect their hosts' breeding success and are engaged in a coevolutionary arms race with hosts that have defenses against parasitism. © 2017 American Ornithologists' Union.
Business-Design Laboratory: a Strategy for Innovation
(2011-12-01) Montoya Peláez, Guillermo León
The contribution of industrial design schools to the development of innovative products is well known around the industrialized world. In Latin American countries like Colombia, industrial design is a relatively young practice and the market is not yet aware of the importance of design as a factor for innovation. Colombia’s industry creativity is just emerging. For many years focus was put on production and contract manufacturing. Today, however, Eastern countries do it on a more larger-scale and at low prices. This condition has forced the academia to look for ways of linking companies with students and thus, developing more competitive innovation products.
Caracterización fitoquímica de una fracción de biflavonoides de garcinia madruno: su inhibición de la oxidación de ldl humana y su mecanismo de estabilización de especies radicalarias
(Universidad de Antioquia, 2009-09-22) Osorio D., Edison
A una fracción biflavonoide (FB) caracterizada fitoquímicamente de Garcinia madruno (Clusiaceae), se le evalúa su potencial inhibitorio de la oxidación de LDL y su capacidad estabilizadora de especies radicalarias, correlacionando dichas actividades con su contenido en biflavonoides. Los biflavonoides morelloflavona, volkensiflavona y amentoflavona se identifican a partir de la FB. El extracto que contiene la FB (extracto AcOEt) se determina como el principal factor involucrado en la actividad estabilizadora de radicales libres de esta especie vegetal, obteniendo la actividad estabilizadora del radical DPPH• a una concentración de 4,50 µg/mL. La peroxidación inducida con CuSO4 de las lipoproteínas de baja densidad, se reduce significativamente en presencia de FB (CE50 = 11,85 µg/mL). El biflavonoide morelloflavona se determina como el principal responsable de la protección ejercida por la FB frente a la actividad estabilizadora de radicales libres y la peroxidación lipídica, aunque posiblemente existan procesos de sinergismo. Estas propiedades sugieren que la FB de G. madruno es un excelente candidato para ser utilizado como antioxidante.
Classical mechanics of dipolar asymmetric top molecules in collinear static electric and nonresonant linearly polarized laser fields: energy-momentum diagrams, bifurcations and accessible configuration space
(World Scientific Publishing, 2008-02-08) Arango Mambuscay, Carlos Alberto
We study classical energy-momentum ($E$-$m$) diagrams for rotational motion of dipolar asymmetric top molecules in strong external fields. Static electric fields, nonresonant linearly polarized laser fields, and collinear combinations of the two are investigated. We treat specifically the molecules iodobenzene (a nearly prolate asymmetric top), pyridazine (nearly oblate asymmetric top), and iodopentafluorobenzene (intermediate case). The location of relative equilibria in the $E$-$m$ plane and associated bifurcations are determined by straightforward calculation, with analytical results given where possible. In cases where analytical solutions cannot be obtained, we resort to numerical solutions, while keeping a geometrical picture of the nature of the solutions to the fore. The classification we obtain of the topology of classically allowed rotor configuration space regions in the $E$-$m$ diagram is of potential use in characterization of energy eigenstates of the corresponding quantum mechanical problem.

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