SPATIAL IMAGES AND PERCEPTION OF RESIDENTIAL DESIRABILITY IN SINGAPORE

Bachelor'sBACHELOR OF ARTS (HONOURS

Significance of the globally threatened Straw-headed Bulbul Pycnonotus zeylanicus populations in Singapore: a last straw for the species?

The globally threatened Straw-headed Bulbul Pycnonotus zeylanicus is one of South-East Asia’s most imperilled songbirds due to the surging demand for the species in the regional bird trade. Recently uplisted from Vulnerable to Endangered, populations of the Straw-headed Bulbul have been extirpated from Java, Thailand and possibly Sumatra while those in Borneo and Peninsular Malaysia are in decline. Intriguingly, a significant yet rarely documented population of this species persists in Singapore. A major stronghold in Singapore is Ubin Island where a population is known since the 1920s. Using a long-term citizen science dataset rarely available for South-East Asian bird species, we determined the status and population trends of the Straw-headed Bulbul in Singapore over a 10–15 year period using Poisson regression models and standardised population indices. We found that the Straw-headed Bulbul population has increased at a rate of 3.69 ± 1.21% per annum on Ubin Island, while the population on Singapore Island remained stable (0.56% per annum) from 2000 to 2016. The population trends in Singapore contrast starkly with the declines reported elsewhere in South-East Asia. We estimated the population in Singapore to be a minimum of 202 individuals, distributed over multiple forest patches. The largest subpopulation of about 110 adult individuals persists on Ubin and which alone forms between 6.5–18.3% of the estimated global population in 2016. Given this unique situation, we recommend a number of conservation measures for the Straw-headed Bulbul to better protect the species, including: (1) an expansion of the protected area network in Singapore to include Ubin as a reserve, (2) the development of an endangered species management plan and, (3) the establishment of ex-situ conservation programmes in zoological institutions and wildlife centres in the region

Physical characterization of Tobramycin Inhalation Powder: II. State Diagram of an Amorphous Engineered Particle

Tobramycin Inhalation Powder (TIP) is a spray-dried engineered particle formulation used in TOBI® Podhaler™, a drug/device combination for treatment of cystic fibrosis. A TIP particle consists of two phases: amorphous, glassy tobramycin sulfate and a gel-phase phospholipid (DSPC). The objective of this work was to characterize both the amorphous and gel phases following exposure of TIP to a broad range of relative humidity and temperature. Because changes in either particle morphology or the solid-state form of the drug could affect drug delivery or biopharmaceutical properties, understanding physical stability was critical to development and registration of this product. This characterization included morphological assessments of particles, thermal analysis to measure the gel-to-liquid crystalline phase transition (Tm) and the glass transition temperature (Tg), enthalpy relaxation measurements to determine structural relaxation times, and gravimetric vapor sorption to measure moisture sorption isotherms of TIP and its components. Collectively, these data enabled development of a state diagram for TIP, a map of the environmental conditions under which physical stability can be expected. This diagram shows that, under long-term storage conditions, TIP is at least 50°C below the Tg of the amorphous phase and at least 40°C below the Tm of the gel phase. Enthalpy relaxation measurements demonstrate that the characteristic structural relaxation times under these storage conditions are many orders of magnitude greater than that at Tg. These data, along with long-term physicochemical stability studies conducted during product development, demonstrate that TIP is physically stable, remaining as a mechanical solid over timescales and conditions relevant to a pharmaceutical product. This met a key design goal in the development of TIP: a room-temperature-stable formulation (three years at room temperature) that obviates the need for refrigeration for long-term storage. This has enabled development of TOBI® Podhaler™ - an approved inhaled drug product that meaningfully reduces the treatment burden of cystic fibrosis patients worldwide

Discovery of Tetrahydropyrazolopyrimidine Carboxamide Derivatives As Potent and Orally Active Antitubercular Agents

Tetrahydropyrazolo­[1,5-<i>a</i>]­pyrimidine scaffold was identified as a hit series from a <i>Mycobacterium tuberculosis</i> (Mtb) whole cell high through-put screening (HTS) campaign. A series of derivatives of this class were synthesized to evaluate their structure–activity relationship (SAR) and structure–property relationship (SPR). Compound <b>9</b> had a promising in vivo DMPK profile in mouse and exhibited potent in vivo activity in a mouse efficacy model, achieving a reduction of 3.5 log CFU of Mtb after oral administration to infected mice once a day at 100 mg/kg for 28 days. Thus, compound <b>9</b> is a potential candidate for inclusion in combination therapies for both drug-sensitive and drug-resistant TB