Femtosecond pulsed laser deposition and patterning of thin films for MEMS

Procedural variables such as fluence, polarization, pulse width, machining speed, and material properties are investigated to determine their effects on the PLD and laser micromachining of aluminum magnesium boride. In this work, a 120-fs pulsed, 800-nm wavelength Ti: Sapphire laser was used for micromachining thin films of ultra-hard AlMgB14 and polysilicon thin films on silicon substrate. Polysilicon was first deposited by low-pressure chemical vapor deposition followed by boride using femtosecond pulsed laser deposition. Channels were then machined in thin films to pattern a device that would produce a linear resistance/deflection curve. Results show that the ultrafast laser has precisely ablated the thin films. However, the high-energy fluence used in single-pass surface micromachining enabled the formation of recast layer of molten silicon substrate ejected by vapor pressure, and conglomerates of re-condensed material at a distance from the feature. Multi-pass surface micromachining at low energy fluences eliminated the recast layers and produced clean features. Ultrafast laser micromachining is certainly beneficial over wet and dry etching in reproducibility, material choice, and minimal number of processing steps. Thin films of ultra-hard AlMgB14 were grown on Si (100) substrates at 300 K using femtosecond pulsed Ti:sapphire laser and subsequently annealed in argon gas up to 1373 K for two hours. X-ray photoelectron spectroscopy, X-ray diffraction, atomic force microscope, and nanoindentation were employed to study the composition, microstructure and hardness of thin films. Results were compared with nanosecond pulsed KrF excimer laser-deposited films. The as-deposited and post-annealed films (up to 1173 K), independent of the pulse width, exhibited amorphous structures with a hardness of 40 GPa. However, post-annealing at higher temperatures has varied effects on crystallization depending on the pulse width. The effect of pulse width on the microstructure and quality of thin films is discussed

Development and validation of an objective swine feet and leg conformation procedure using digital imagery

The objectives of this thesis were i) to develop and assess repeatability of an objective method for evaluating feet and leg conformation in high parity sows and ii) to validate and examine measurements using the developed objective method with a group of pedigreed gilts from age at selection through their first parity and into their second gestation. For the first objective, 45 multiparous sows (average parity 6.7 ± 2.5; parity range 5 to 14) from two commercial farms (n = 21 farm one and n = 24 farm two) were used. Sows were moved to a pen where digital images of the profile and rear stance were captured. On average, 2.8 and 8.1 final profile images were used per sow at farm one and farm two respectively. Farm two had over twice the number of profile images as farm one, as farm one was taken from the right side only whereas farm two had both left (average 4.2) and right (average 3.9) profile images. Additionally, 2.6 rear stance images were used for measurement per sow. A joint angle measuring system was devised to collect angle measurements on the knee, front and rear pastern, hock and rear stance. Joint measurements were analyzed using mixed model methods, including farm, side of measurement and parity as fixed effects and sow as a random effect. Intraclass correlation coefficients were calculated to evaluate process repeatability. No significant farm or parity differences were observed for joint angles measured except for the knee angle between farms (P \u3c 0.05) and the hock angle between sows parity six and ≥ seven (P \u3c 0.05). Side was significantly different in all joints measured (P \u3c 0.05), except for in the rear stance measurement where side is not applicable. Joint angle measurement repeatability ranged from 0.58 to 0.87. Lowest and highest repeatabilities were observed for the knee and hock angle measurements, respectively. For the second objective, gilts were selected from a single population and moved to three different farms. Profile and rear stance images were obtained from gilts at selection (319; average age 21.6 ± 1.8 weeks; range 19 to 25) and during their second gestation (277; average gestation 26.7 ± 17.2 days; range 0 to 87). Knee, front and rear pastern, hock, and rear stance joint angles were measured using image analysis software. To evaluate symmetry and joint angle differences due to age between the same individual, only females with repeated measures at selection and post first parity, when second gestation days were between 0 to 21 (126 females), were used. Mixed model equations were used including parity (zero or one) and profile side (left or right) as fixed effects. Parity was included as a repeated variable with the animal as the subject. Knee and rear pastern angles decreased (weakened) and hock angles increased (straightened) as age progressed (P \u3c 0.05). All joint measurements were symmetric between left and right legs (P \u3e 0.05) except for the hock where a difference (P \u3c 0.05) was observed. To evaluate gestation age effects on joint angles, only the measurements taken during the second gestation were used. Data was analyzed using mixed model equations including farm and side as fixed effects and gestation age as continuous covariate and animal was included as random effect. Farm was a significant source of variation for knee, front and rear pasterns, and rear stance angle measurements (P \u3c 0.05). Additionally, asymmetry was detected in knee, and front and rear pasterns (P \u3c 0.05). Front pastern and hock angles increased (straightened) as gestation age increased, while knee angle decreased (weakened) (P \u3c 0.05). Heritability estimates were low to moderate for profile angles and was not estimable for the rear stance position. Results suggest that as age increases leg structure changes, with the rear leg joints showing greater variation from selection to first parity. Results also suggest that environmental factors such as farm where animals are housed could contribute to angle differences. Small angle changes in the front leg could indicate structure may change over the life of the animal; however, rear leg structure and its impact on longevity still require further investigation. Results from this body of work have set the ground work for an objective feet and leg joint conformation method using digital imagery. It is still necessary to look further into the life of the animal and understand the full genetic control over the change in structure until complete physical maturity and its association with lifetime productivity in the sow

Pictorial Depiction of the Lying-down Behavior of Lame and Non-lame Multiparous Gestating Sows

This study was designed to pictorially depict and compare the lying-down sequence (i.e. postures adopted and movements during the process) in non-lame versus lame gestating sows. Ten multiparous sows (average parity 3.5 ± 1.6) with different degrees of lameness (lameness assessed on a 6 point scale where 0 =normal to 5 = severely lame, will not stand/move) were video recorded in a gestation pen during one lying-down event to identify the postures and movements adopted during the lying-down sequence. There was no difference among lameness scores in the postures or movements during the lying-down sequence of the observed sows except for the sow classified as severely lame (i.e. lameness score = 4) that showed uncontrolled lying-down behavior and finished the lying-down sequence on a “dog sitting” position. Results suggest that lameness score does not greatly affect the lying-down sequence when space restriction is not an issue. However, this could be due to the limited sample size and/or that lameness recorded in this study was not severe enough to affect lying-down behavior

Prolapse Incidence in Swine Breeding Herds Is a Cause for Concern

Beginning in the fall of 2014 there has been a general and widespread increase in the incidence of prolapse in the U.S. swine herd. The purpose of this manuscript is to review the incidence, causative factors and treatment of rectal, vaginal, uterine and preputial prolapses. Rectal and vaginal prolapses are most common in swine when compared to other prolapse types. The cause of prolapses supports a fixation mechanism failure overcome by pressure on or weakening of support tissue. The fundamental factors affecting the incidence for prolapses are many and include factors related to nutrition, physiology, hormones, genetics, environment and other disease factors such as chronic diarrhea, cough, and dystocia. Treatment of prolapsed swine includes surgical and therapeutic management that can lead to complete recovery. However, in most cases, euthanasia is the final result. Economic loss was calculated at approximately $5220 dollars/year/1000 sows

Digital Evaluation of Structural Phenotypes Common among Higher Parity Crossbred Sows

Two independent, commercial, crossbred sow populations were selected to compare feet and leg structure in order to identify commonalities among them that may contribute to their long herd life. Digital imagery was used to measure the angle of the knee, pasterns and hock joints as well as the overall rear stance in sows ranging from parity 5 to 14. Parity and population effects were evaluated for each angle analyzed. Significant population effects (P\u3c 0.05) were observed for the angle of the knee. Significant parity effects (P\u3c0.05) were observed for the angle of rear leg stance. Similar leg conformation values across populations and parities for the front and rear pasterns and the hock may suggest that these values are within an acceptable range to allow for long herd life

Optical Testing of Retroreflectors for Cryogenic Applications

A laser tracker (LT) is an important coordinate metrology tool that uses laser interferometry to determine precise distances to objects, points, or surfaces defined by an optical reference, such as a retroreflector. A retroreflector is a precision optic consisting of three orthogonal faces that returns an incident laser beam nearly exactly parallel to the incident beam. Commercial retroreflectors are designed for operation at room temperature and are specified by the divergence, or beam deviation, of the returning laser beam, usually a few arcseconds or less. When a retroreflector goes to extreme cold (.35 K), however, it could be anticipated that the precision alignment between the three faces and the surface figure of each face would be compromised, resulting in wavefront errors and beam divergence, degrading the accuracy of the LT position determination. Controlled tests must be done beforehand to determine survivability and these LT coordinate errors. Since conventional interferometer systems and laser trackers do not operate in vacuum or at cold temperatures, measurements must be done through a vacuum window, and care must be taken to ensure window-induced errors are negligible, or can be subtracted out. Retroreflector holders must be carefully designed to minimize thermally induced stresses. Changes in the path length and refractive index of the retroreflector have to be considered. Cryogenic vacuum testing was done on commercial solid glass retroreflectors for use on cryogenic metrology tasks. The capabilities to measure wavefront errors, measure beam deviations, and acquire laser tracker coordinate data were demonstrated. Measurable but relatively small increases in beam deviation were shown, and further tests are planned to make an accurate determination of coordinate errors

Characterization and Symmetry Study of Objective Feet and Leg Joint Measurements in Five Separate Lines of Maternal Gilts

This study involves the initial measurement and joint description of five maternal gilt lines for the validation of objectively measured feet and leg joint angles in regards to sow longevity. The initial measurement was used to characterize all gilts used in the study based on age and line as well as to study the symmetry between the left and right sides of the animals’ body. Significant differences (P \u3c 0.05) between lines were identified in both pasterns. Results suggest (P \u3c 0.05) that the knee and the hock angles increase with age. Symmetry difference, difference between right and left, (P \u3c 0.05) was observed in the knee. These measurements will be used in association with production records through the animals’ first parity to validate past joint measurements from sows that have remained in their respective herds longer than their contemporaries and to identify a range of acceptable joint angles that allow an animal to remain in the herd for a long production life

Phenotypic and Genetic Associations of Objectively Evaluated Replacement Female Feet and Leg Joint Conformation at Selection and Post First Parity

Objective evaluation of feet and leg joint conformation is a needed step to improve the repeatability of selection of animals based on proper structure. Objective measurements were taken at the time of selection and during second gestation. Phenotypic and genetic parameter estimates were obtained to better understand the relationship between the measures obtained from objective evaluation. Heritability estimates were low to moderate for all traits measured. Genetic correlations between and within traits at the same time point and between time points were all either small or not different than zero. Low to moderate heritability estimates indicate the ability for these traits to be selected upon effectively. Likewise, low genetic correlations indicate that traits may be selected independent of one another. Therefore, each joint in the objective evaluation can carry its own weight, which will require further investigation beyond the scope of this article

Prevalence of, and Resident and Facility Characteristics Associated With Antipsychotic Use in Assisted Living vs. Long-Term Care Facilities: A Cross-Sectional Analysis from Alberta, Canada

BACKGROUND: Potentially inappropriate antipsychotic use in long-term care (LTC) facilities has been the focus of significant policy and clinical attention over the past 20 years. However, most initiatives aimed at reducing the use of these medications have overlooked assisted living (AL) settings. OBJECTIVE: We sought to compare the prevalence of antipsychotic use (including potentially inappropriate use) among older AL and LTC residents and to explore the resident and facility-level factors associated with use in these two populations. METHODS: We performed cross-sectional analyses of 1089 residents (mean age 85 years; 77% female) from 59 AL facilities and 1000 residents (mean age 85 years; 66% female) from 54 LTC facilities, in Alberta, Canada. Research nurses completed comprehensive resident assessments at baseline (2006-2007). Facility-level factors were assessed using standardized administrator interviews. Generalized linear models were used to estimate odds ratios for associations, accounting for clustering by facility. RESULTS: Over a quarter of residents in AL (26.4%) and LTC (31.8%) were using antipsychotics (p = 0.006). Prevalence of potentially inappropriate use was similar in AL and LTC (23.4 vs. 26.8%, p = 0.09). However, among users, the proportion of antipsychotic use deemed potentially inappropriate was significantly higher in AL than LTC (AL: 231/287 = 80.5%; LTC: 224/318 = 70.4%; p = 0.004). In both settings, comparable findings regarding associations between resident characteristics (including dementia, psychiatric disorders, frailty, behavioral symptoms, and antidepressant use) and antipsychotic use were observed. Few facility characteristics were associated with overall antipsychotic use, but having a pharmacist on staff (AL), or an affiliated physician (LTC) was associated with a lower likelihood of potentially inappropriate antipsychotic use. CONCLUSION: Our findings illustrate the importance of including AL settings in clinical and policy initiatives aimed at reducing inappropriate antipsychotic use among older vulnerable residents