The fabrication of aspherical microlenses using focused ion-beam techniques.

Aspheric lenses are the most common method for correcting for spherical aberrations but, in microlens production, highly-controlled lens profiles are hard to achieve. We demonstrate a technique for creating bespoke, highly-accurate aspheric or spherical profile silicon microlens moulds, of almost any footprint, using focused ion-beam milling. Along with this, we present a method of removing induced ion-beam damage in silicon, via a hydrofluoric acid etch, helping to recover the surface's optical and chemical properties. In this paper, we demonstrate that our milled and etched moulds have a roughness of 4.0-4.1 nm, meaning they scatter less than 1% of light, down to wavelengths of 51 nm, showing that the moulds are suitable to make lenses that are able to handle light from UV up to infra-red. Using empirical experiments and computer simulations, we show that increasing the ion-dose when milling increases the amount of gallium a hydrofluoric acid etch can remove, by increasing the degree of amorphisation within the surface. For doses above 3000 µC/cm(2) this restores previous surface properties, reducing adhesion to the mould, allowing for a cleaner release and enabling higher quality lenses to be made. Our technique is used to make aspheric microlenses of down to 3 µm in size, but with a potential to make lenses smaller than 1 µm.

Perceptions of clinical role modelling: an exploration of nursing students' experiential learning.

The purpose of this study was to reveal the essence of role modelling in relation to learning in the clinical field from the nursing student's perspective. Twenty-one final year nursing undergraduates voluntarily and purposefully participated as informants in the study. Each participated in a face-to-face interview with a nurse researcher. In addition, a focus group interview session was conducted with seven of the participating students. Using the phenomenological method, the essence of role modelling emerged as a core theme which was linked to the students' clinical learning experiences. Multi-dimensional elements of learning that were contingent upon role modelling were categorised into five major themes: Expectations of self and others; Situational conditional factors; Situational anxiety--reality of fear/nervousness; Application of theoretical knowledge to practice; and, Experiential knowledge--an active learning process. The students' experiences of how role modelling impacted on their learning has implications for nursing education. It is necessary to acknowledge the variety of health carers, and in particular, the clinical nurse educator, who have consequential influences on student learning in the clinical field.

Relationship between the onset of oestrus, the preovulatory surge in luteinizing hormone and ovulation following oestrous synchronization and superovulation of farmed red deer (Cervus elaphus).

The timing of ovulation relative to the onset of oestrus and the preovulatory surge in luteinizing hormone (LH) was studied in red deer following treatments to synchronize oestrus and induce either a monovulatory or superovulatory response. Mature hinds (n = 36) were allocated randomly to two mating groups (n = 16 + 20), with respective treatments staggered by 4 weeks during the 1990 rut (March-April). Each hind was treated with an intravaginal controlled internal drug releasing (CIDR)-type S device for 14 days. Treatments to induce a monovulatory response included CIDR device alone (treatment A; n = 4 + 8) and additional injection of 200 iu pregnant mares' serum gonadotrophin (PMSG) at device removal (treatment B; n = 4 + 4). Treatments to induce a superovulatory response included injections of 200 iu PMSG and 0.5 units ovine follicle-stimulating hormone (FSH) at about time of removal of CIDR devices (treatment C; n = 4 + 4) and further treatment with gonadotrophin-releasing hormone (GnRH) analogue 18 h after removal of CIDR devices (treatment D; n = 4 + 4). The hinds were run with crayon-harnessed stags from insertion of CIDR devices (12 March or 9 April) and blood samples were taken every second day to determine plasma progesterone. Further blood samples were collected for determination of plasma LH and progesterone via indwelling jugular cannulae every 2 h for 72 h from removal of CIDR devices. Hinds were allocated randomly to an initial ovarian examination by laparoscopy at either 16 or 20 h (A and B), or 12 or 16 h (C and D) after the onset of oestrus, with laparoscopy repeated at intervals of 8 h until either ovulation was recorded (A and B), or for four successive occasions (C and D). All hinds received cloprostenol injections 15 days after device removal. A total of 28 hinds (78%) exhibited oestrus and a preovulatory LH surge, with mean (+/- SEM) times to onset of oestrus of 44.6 +/- 1.0 h (A; n = 7), 37.4 +/- 2.0 h (B; n = 7), 16.3 +/- 1.7 h (C; n = 6) or 14.0 +/- 1.7 h (D; n = 8). Failure to exhibit oestrus or LH surge was most prevalent among hinds in treatment A early in the rut.(ABSTRACT TRUNCATED AT 400 WORDS)

Laparoscopic intra-uterine insemination of fallow deer with frozen-thawed or fresh semen after synchronisation with CIDR devices.

This study investigated the efficacy of fixed-time laparoscopic intra-uterine insemination of farmed fallow deer (Dama dama) with frozen-thawed or fresh semen. In the trials with frozen-thawed semen, a total of 547 mature non-lactating does across five New Zealand farms were used. For oestrous synchronisation and artificial insemination, a standard control regimen was applied to at least 30% of the does on each farm, involving the insertion of single CIDR type-G devices intravaginally for 14 days, deposition of 50 x 10(6) frozen-thawed spermatozoa at 65 hours after withdrawal of the CIDR device and the continuous presence of vasectomised bucks from the insertion of the CIDR device until 10 days after insemination. Various aspects of this protocol were changed for the remaining does on each farm, including inseminations at 60 or 70 hours, the absence of vasectomised bucks, insemination with 25 x 10(6) or 10 x 10(6) spermatozoa, synchronisation with CIDR type-S devices and synchronisation with prostaglandin. The conception rate, based on rectal ultrasonography at 45 days after insemination, was 67% across all treatments (n=547). Corrected conception rates (+/-s.e.), calculated following between-farm adjustments, were 67+/- 3% for the control regimen, 67+/- 9% and 73 +/- 8% for inseminations at 60 and 70 hours respectively, 61 +/- 9% for absence of bucks, 80 +/- 8% and 74 +/- 9% for inseminations with 25 x 10(6) and 10 x 10(6) spermatozoa respectively, 62 +/- 10% for CIDR type-S device synchronisation, and 49 +/- 10% for prostaglandin synchronisation. Despite apparent differences, none of the treatments resulted in adjusted conception rates that were significantly different from the control regimen (P>0.01). In the trials with fresh semen, 216 does in the USA were inseminated at 69-71 hours after withdrawal of the CIDR device using either cryopreserved semen from New Zealand (n=158; 25 x 10(6) spermatozoa per inseminate) or fresh semen (n=58; 7.5 x10(6) to 20 x 10(6) spermatozoa per inseminate) collected less than 10 hours earlier. The overall conception rates were 77% and 81% respectively, with no significant differences between semen type (frozen v. fresh) or fresh spermatozoa number per inseminate (P>0.01). A further 102 does in New Zealand similarly received fresh semen from 3/4 Mesopotamian buck. Doses of 10 x 10(6) (n=35), 5 x 10(6) (n=32) or 2.5 x 10(6) (n=35) spermatozoa per inseminate were delivered at 69-71 hours after withdrawal of the CIDR device. The conception rates were 77%, 66% and 51% respectively, reflecting a dose effect (P<0.05). However, 1/4 Mesopotamian does in the group (n=19) exhibited higher conception rates (95% overall) irrespective of semen dose, possibly indicating a semen/recipient genotype interaction. It is concluded that laparoscopic intra-uterine insemination of fallow deer with frozen-thawed or fresh semen at fixed intervals after removal of a CIDR device can give acceptable conception rates under a range of on-farm management options and semen doses.