The Chittagong story: studies on the ecology of rat floods and bamboo masting

Rodent population outbreaks due to the 50-year cycle of gregarious flowering and seed masting of Melocanna baccifera were first noted in the Chittagong Hill Tracts (CHT) of Bangladesh during the crop production cycle of 2008. The wave of flowering has steadily moved southward through the region each year, with seed masting still occurring in some areas of the CHT during 2010. Because of a lack of surveillance, it is not yet known whether all Melocanna bamboo forests across the region have now initiated flowering. Ecological surveys carried out during the masting event have provided some preliminary evidence that nearly all rodent species are able to exploit Melocanna bamboo seeds as a food resource, with nearly 30% of the seed fallen in forests damaged by rodents. Breeding potential of the predominant species found, Rattus rattus, appears to confirm that aseasonal breeding occurs due to the abundant supply of bamboo seed during masting events. These preliminary results obtained from ongoing research surveys are discussed in the context of the management response to the regional famine triggered by the severe crop damage caused by rodent population outbreaks

Spin-Charge Separation and Kinetic Energy in the t-J Model

I show that spin-charge separation in 2-D t-J model leads to an increase of kinetic energy. Using a sum rule, I derive an exact expression for the lowest possible KE (E_{bound}) for any state without doubly occupied sites. KE of relevant slave-boson and Schwinger-boson mean-field states -- which exhibit complete spin-charge separation -- are found to be much larger than E_{bound}. Examination of n(k) shows that the large increse in KE is due to excessive depletion of electrons from the bottom of the band (Schwinger boson) and of holes from the top (slave boson). To see whether the excess KE is simply due to poor treatment of the constraints, I solve the constraint problem analytically for the Schwinger boson case in the J = 0 limit. This restores gauge invariance, incorrectly violated in MF theories. The result is a generalized Hartree-Fock state of the Hubbard model, but one that includes spin waves. Even after constraints are imposed correctly, the KE remains much larger than E_{bound}. These results support the notion, advanced earlier [PRB 61, 8663 (2000)] that spin-charge separation in the MF state costs excessive KE, and makes the state unstable toward recombination processes which lead to superconductivity in d = 2 and a Fermi liquid state in higher dimensions.Comment: 13 pages, LateX plus three figures. To appear in Phys Rev B Typos correcte

Rat floods and water floods: the ecological and sociological dynamics of rodent management in Bangladesh

Chakma, N., Belmain, S.R., Sarker, N.J., Sarker, S.U., Kamal, N.Q., Sarker, S.K

Study on Sedation with Local Analgesia in Calves

. The effect of sedatives and analgesics on heart rate, respiration rate and rectal temperature were observed. Heart rate and respiration rate significantly decreased during sedation with xylazine hydrochloride plus 2% lignocaine hydrochloride or 0.5% bupivacaine hydrochloride. A significantly decreased heart rate and respiration rate also found during sedation with diazepam plus 2% lignocaine hydrochloride or 0.5% bupivacaine hydrochloride. Two percent lignocaine hydrochloride showed short onset, rapid spreading and no side effect. Duration of analgesia was longer with 0.5 % bupivacaine hydrochloride (55.88±1.58 min in Group B and 48±11.25 min in Group D) compared to 2% lignocaine hydrochloride (39.60±5.77 min in Group A and 43.6±5.81 min in Group C). Xylazine hydrochloride showed short onset and long duration of sedation compared to diazepam. So for herniorraphy, xylazine hydrochloride can be used as a better sedative while 0.5 % bupivacaine hydrochloride can be used as a local analgesic for longer duration of action

A strong-coupling expansion for the Hubbard model

We reconsider the strong-coupling expansion for the Hubbard model recently introduced by Sarker and Pairault {\it et al.} By introducing slave particles that act as projection operators onto the empty, singly occupied and doubly occupied atomic states, the perturbation theory around the atomic limit distinguishes between processes that do conserve or do not conserve the total number of doubly occupied sites. This allows for a systematic $t/U$ expansion that does not break down at low temperature ($t$ being the intersite hopping amplitude and $U$ the local Coulomb repulsion). The fermionic field becomes a two-component field, which reflects the presence of the two Hubbard bands. The single-particle propagator is naturally expressed as a function of a $2 \times 2$ matrix self-energy. Furthermore, by introducing a time- and space-fluctuating spin-quantization axis in the functional integral, we can expand around a ``non-degenerate'' ground-state where each singly occupied site has a well defined spin direction (which may fluctuate in time). This formalism is used to derive the effective action of charge carriers in the lower Hubbard band to first order in $t/U$. We recover the action of the t-J model in the spin-hole coherent-state path integral. We also compare our results with those previously obtained by studying fluctuations around the large-$U$ Hartree-Fock saddle point.Comment: 20 pages RevTex, 3 figure

Characterization of a Near-Complete Genome Sequence of a Chaphamaparvovirus from an Australian Boobook Owl (Ninox boobook)

This study reports a complete genome sequence of a variant of psittacine chaphamaparvovirus 2 detected in kidney tissue from an Australian boobook (Ninox boobook), compiled using next-generation sequencing. The genome was 4,312 bp long, encoding four open reading frames. The detection of this variant in boobook represents a significant host-switching event

Genome Sequence of a Beak and Feather Disease Virus from an Unusual Novel Host, Australian Boobook Owl (Ninox boobook)

The beak and feather disease virus (BFDV) is a pathogen of psittacine birds. BFDVs infecting nonpsittacine birds remain largely uncharacterized. We report the genome of a BFDV from a boobook owl (Ninox boobook), a nonpsittacine bird. The genome consisted of 1,993 bp containing two major bidirectionally transcribed open reading frames

Hydrogen absorption properties of amorphous (Ni0.6Nb0.4−yTay)100−xZrx membranes

Ni based amorphous materials have great potential as hydrogen purification membranes. In the present work the melt spun (Ni0.6Nb0.4−yTay)100−xZrx with y=0, 0.1 and x=20, 30 was studied. The result of X-ray diffraction spectra of the ribbons showed an amorphous nature of the alloys. Heating these ribbons below T < 400 °C, even in a hydrogen atmosphere (1−10 bar), the amorphous structure was retained. The crystallization process was characterized by differential thermal analysis and the activation energy of such process was obtained. The hydrogen absorption properties of the samples in their amorphous state were studied by the volumetric method, and the results showed that the addition of Ta did not significantly influence the absorption properties, a clear change of the hydrogen solubility was observed with the variation of the Zr content. The values of the hydrogenation enthalpy changed from ~37 kJ/mol for x=30 to ~9 kJ/mol for x=20. The analysis of the volumetric data provides the indications about the hydrogen occupation sites during hydrogenation, suggesting that at the beginning of the absorption process the deepest energy levels are occupied, while only shallower energy levels are available at higher hydrogen content, with the available interstitial sites forming a continuum of energy levels

The ethnomedicinal, phytochemical and pharmacological properties of Phaleria macrocarpa (Scheff). Boerl

Phaleria macrocarpa (Scheff.) Boerl. is a dense evergreen tree of the family Thymelaeceae. This plant is popular with the name of Mahkota dewa, which is literally translated as God's Crown. All parts of this plant including fruits, seeds, stem, and leaves have well known therapeutic properties and have been extensively used in traditional medicine for the treatment of various diseases such as cancer, diabetes mellitus, allergies, kidney disorders, blood diseases, stroke, and acne with satisfactory results. Scientific findings on bioactivities of P. macrocarpa also demonstrated different pharmacological properties of various parts of this plant including cytotoxic, antidiabetic, antioxidant, anti-inflammatory, antibacterial, and antihypertensive activities. Phytochemicals studies of P. macrocarpa revealed the presence of several classes of compounds such as benzophenones, terpenoids, xanthones, lignans, acids, and sugars. This review aims to provide a critical overview on botanical description, traditional usage, phytochemicals, and pharmacological activities of P. macrocarpa

Effects of meat preheating and wrapping on the levels of polycyclic aromatic hydrocarbons in charcoal-grilled meat.

The contamination of polycyclic aromatic hydrocarbons PAHs by thermally treated high-protein foods, such as charcoal-grilled meat products, is due to the generation by direct pyrolysis of food nutrients and the direct deposition of PAHs from smoke produced through incomplete combustion of the thermal agents. This study investigated the effects on the PAH (BaP, BbFln and Fln) contents by using two different types of treatments, preheating (steam and microwave) and wrapping (aluminium and banana leaf) of the meat samples prior to charcoal grilling. PAHs were extracted through tandem solid-phase extraction. The results showed that the applied preheating and wrapping treatments on the samples strongly affect the PAHs levels in the charcoal-grilled meat. No carcinogenic PAHs (BaP and BbFln) were detected in the samples after steam and microwave preheating or aluminium wrapping treatments. Significant reductions of Fln content, of up to 46% and 81% in beef and chicken samples, respectively, were observed in the study