Stable carbon (?13C) and oxygen (?18O) isotopes of bivalve shells and calcareous sediments of the Mio-Pliocene Nhila Anticline, southeast Bengal Basin, Bangladesh have been investigated to obtain information on paleoclimate and paleoenvironment conditions during deposition. The ?13CPDB, ?18OPDB and ?18OSMOW values in bivalve shell range from -2.81‰ to -1.56‰, -3.57‰ to -2.39‰ and 27.18‰ to 28.40‰ in bivalve shells and -13.90‰ to -1.75‰, -4.71‰ to -2.13‰ and 26.01‰ to 28.66‰ in calcareous sediments, respectively. The ?13CPDB values in bivalve shells are comparable to that of calcareous sediments (~ -1.75‰) in the upper section, but ?13CPDB values in calcareous sediments are more negative excursion towards lower section (up to -13.90‰). These results signify that salinity gradients could modified the isotope values and/or strong influence of freshwater conditions. The variable ?18OPDB values in both bivalve shell and calcareous sediment suggesting diagenetic alteration of carbonates and water temperature effects. The more negative ?18OPDB values imply humid paleoclimatic conditions during the Mio-Pliocene sedimentation. Therefore, the ?18OPDB values of the Mio-Pliocene sediments of Nhila Anticline are probably controlled by paleotemperature leading to intensification of high rainfall. DOI: http://dx.doi.org/10.3329/jles.v8i0.20155 J. Life Earth Sci., Vol. 8: 113-117, 2013

The main focus of the study was to assess the extent of perception level of potato growers towards the potato production technologies. The study was carried out in the Rajshahi district which is considered as a part of the northwest area of Bangladesh. Two hundred thirty-two farmers were randomly selected as potato growers for data collection from twenty villages under the Upazilla namely, Mohonpur, Bagmara and Durgapur of Rajshahi district. A pre-tested interview schedule was used to collect the data from the respondents in July 2010 to February 2011. For measuring the perception of modern variety potato production technologies by the potato growers, 11 technologies for modern variety potato production were considered. Descriptive statistical measures such as number, percentage distribution, range, mean, standard deviation and coefficient of variation were used in describing the variable. More or less similar percentage (37%) of the growers had medium and high perception whereas 26.29 percent low perception. Analysis indicated that among the extent of perception of modern eleven technologies use of quality seed was at top highest ranking by the perception adoption index of 253.88, whereas plant spacing was bottom lowest. The perception variations in different technologies will not be improved unless intensive and effective steps are taken to increase grower’s access to various information sources of agriculture which increase the knowledge and then perception. DOI: http://dx.doi.org/10.3329/jles.v8i0.20140 J. Life Earth Sci., Vol. 8: 55-61, 2013

Sodium arsenite (NaAsO2) considered effective for aquatic weed control, has been found to be harmful to several species of freshwater teleost fishes. Channa punctata was exposed to NaAsO2 at the concentrations of 100?l/30g and 200?l//30g body weight per fish and cultured for 14 days post exposure respectively. Tissue disorientation, peliosis and vacuolization accompanied by karyolysis, apoptosis and necrosis in the liver and heart were significant on days onwards. Irregularities in the intestines including apoptotic and necrotic cells were also common, enlargement of the mucosa and submucosa was noted. Corresponding with the histopathological lesions, necrosis of liver cells and intestinal functions or induction of heart muscles at the early phase of arsenic exposure may be the possible causes of fish death. DOI: http://dx.doi.org/10.3329/jles.v7i0.20123 J. Life Earth Sci., Vol. 7: 67-70, 2012

DOI: http://dx.doi.org/10.3329/jles.v7i0.20128 J. Life Earth Sci., Vol. 7: 99-104, 2012

DOI: http://dx.doi.org/10.3329/jles.v6i0.9730 JLES 2011 6: 109-112

DOI: http://dx.doi.org/10.3329/jles.v6i0.9729 JLES 2011 6: 105-108 DOI: http://dx.doi.org/10.3329/jles.v6i0.9729 JLES 2011 6: 105-108

The study conducted an empirical investigation on self-concept as related to gender, parental profession and academic achievement among early-adolescent boys and girls in various institutions of Rajshahi city. A total of 160 respondents constituted the sample of the study. A 2×2×2 factorial design involving two levels of gender (boy/girl), two levels of parental profession (service/business) and two levels of academic achievement (high achiever/low achiever) were used. The results showed significantly higher self-concept of girls than boys. In case of academic achievement high achievers expressed significantly more positive self-concept than low achievers. In case of parental service, high achiever boys and high achiever girls expressed significantly more positive self-concept followed by their counterpart low achievers. In case of parental business, it was found that high achiever girls expressed significantly more positive self-concept than low achiever girls. However no significant mean difference was obtained between high achiever boys and low achiever boys in case of parental business. Thus, self-concept of young children was found to be determined by gender, parental profession and academic achievement during early adolescent stage. DOI: http://dx.doi.org/10.3329/jles.v6i0.9728 JLES 2011 6: 97-103

To detect the effect of ultraviolet (UV) radiation on some economic traits of the silkworm, Bombyx mori L. variety Urboshi-1, 5-day old pupae were irradiated with 366nm wavelength of UV-rays at a distance of 10.6 cm for 1, 5 and 10 min. UVradiation had significant effects on majority of the 16 characters considered for the study. Three different lines viz. U1-DW, U1- LW and U10-LD were isolated on the basis of their cocoon shape and size from the rearing of the 1st radiated generation (R1). The rearing of the R2 generation produced cocoons which conformed to the shape and size of the cocoons as selected in the R1 generation. The selected lines showed better rearing performance than the control for majority of the characters, especially the cocoon characters which had direct relationships with the commercial cocoon production. Cocoons produced in the R2 generation were utilized in the R3 generation. The evaluation of the cocoon characters of the R3 generation revealed that U1-LW and U10- LD lines hold promise for commercial exploitation. Moreover, U10-LD also showed the lowest larval mortality. DOI: http://dx.doi.org/10.3329/jles.v6i0.9718 JLES 2011 6: 33-37

An investigation was conducted during the period from March to December 2009 to investigate the induced spawning practices in 22 hatcheries of 6 Upazilas of Rajshahi District of Bangladesh. It was observed that, 6 native fish species viz. rui (Labeo rohita), catla (Catla catla), mrigal (Cirrhina mrigala), calibaush (Labeo calbasu), bata (Labeo bata), gonia (Labeo gonius) and six exotic fish species such as silver carp (Hypophthalmichthys moltrix), bighead carp (Aristichthys nobilis), grass carp (Ctenopharyngodon idella), common carp (Cyprinus carpio), Thai pangus (Pangasius sutchi), rajputi (Puntius gonionotus) were used in the surveyed hatcheries for induced spawning purpose. The average length limit was 41.70±13.02 to 72.81±25.98 cm, average age limit was 1.96±0.75 to 3.08±0.90 years and average weight limit was 1.83±0.79 to 7.54±3.92 kg of the brood fish. Two types of hormone injections like PG (pituitary gland) and HCG (human chorionic gonadotropin) were used for induced spawning. The rate of 1st doses of injections of PG were from 1 to 4 mg/kg and HCG from 150 to 500 IU/kg and the rate of 2nd doses of injections of PG for native and exotic species were from 4 to 8 mg/kg and 4 to 10 mg/kg respectively. The incubation period and hatching rate in different fish species varied from 10 to 72 hours and 55% to 80%, respectively. DOI: http://dx.doi.org/10.3329/jles.v6i0.9723 JLES 2011 6: 65-68