Gradient-index Alvarez lenses: publisher's note

This publisher's note contains a correction to Appl. Opt.62, 3485 (2023)APOPAI0003-693510.1364/AO.487089.

Gradient-index Alvarez lenses

Gradient-index Alvarez lenses (GALs), a new, to the best of our knowledge, type of freeform optical component, are surveyed in this work for their unique properties in generating variable optical power. GALs display similar behavior to conventional surface Alvarez lenses (SALs) by means of a freeform refractive index distribution that has only recently been achievable in fabrication. A first-order framework is described for GALs including analytical expressions for their refractive index distribution and power variation. A useful feature of Alvarez lenses for introducing bias power is also detailed and is helpful for both GALs and SALs. The performance of GALs is studied, and the value of three-dimensional higher-order refractive index terms is demonstrated in an optimized design. Last, a fabricated GAL is demonstrated along with power measurements agreeing closely with the developed first-order theory.

Lower serum magnesium is associated with vascular calcification in peritoneal dialysis patients: a cross sectional study

BACKGROUND

Coronary artery calcification (CAC) is highly prevalent among dialysis patients and is associated with increased cardiovascular and all cause mortality. Magnesium (Mg) inhibits vascular calcification in animal and in-vitro studies but whether the same effect occurs in humans is uncertain.

METHODS

A single centre cross-sectional study of 80 prevalent peritoneal dialysis (PD) patients; on PD only for a minimum of 3 months. A radiologist blinded to patient status calculated their abdominal aortic calcification (AAC) scores on lateral lumbar spine radiographs, a validated surrogate for CAC.

RESULTS

Eighty patients provided informed consent and underwent lumbar spine radiography. The mean serum Mg was 0.8 mmol/L (standard deviation 0.2) and mean AAC score 8.9 (minimum 0, maximum 24). A higher serum Mg level was associated with a lower AAC score (R ² = 0.06, unstandardized coefficient [B] = -7.81, p = 0.03), and remained after adjustment for age, serum phosphate, serum parathyroid hormone, low-density lipoprotein cholesterol, smoking history, and diabetes (model adjusted R ² = 0.36, serum Mg and AAC score B = -11.44, p = 0.00). This translates to a 0.1 mmol/L increase in serum Mg being independently associated with a 1.1-point decrease in AAC score.

CONCLUSIONS

Our findings suggest that Mg may inhibit vascular calcification. If this association is replicated across larger studies with serial Mg and vascular calcification measurements, interventions that increase serum Mg and their effect on vascular calcification warrant further investigation in the PD population.

Increased allocation of adult-acquired carbohydrate to egg production results in its decreased allocation to sex pheromone production in mated females of the moth Heliothis virescens

Females of most species of moths produce a volatile sex pheromone that attracts conspecific males over distance. In females of the polyandrous moth Heliothis virescens, feeding on carbohydrate (e.g. nectar) supplies precursor, via hemolymph trehalose, for both sex pheromone and egg production. With limited carbohydrate acquisition these two reproductive physiologies might compete for hemolymph trehalose, resulting in an allocation deficit to either sex pheromone or egg production. Using virgin and mated females, which have low and high egg maturation rates, respectively, we fed females a limited diet of (13)C-labeled glucose daily and, using mass isotopomer distribution analysis, determined allocations of adult-acquired carbohydrate (AAC) to newly synthesized pheromone and ovarian and egg fats, our proxies for allocation to egg production. With increased number of feeds, AAC enrichment of hemolymph trehalose increased, as expected. This led to mated females increasing their proportional allocation of AAC to ovarian and egg fats, but decreasing their proportional allocation of AAC to pheromone production. By contrast, virgins increased their proportional allocation of AAC to pheromone production with increased feeds, consistent with increasing AAC enrichment of hemolymph trehalose. These results show that with limited AAC intake, enhanced egg maturation in mated females results in reduced AAC allocation to pheromone production; this does not occur in virgins because of their lower egg maturation rate. This physiological competition for AAC corresponded with decreased pheromone production in mated moths to levels unlikely to attract mates. Therefore, the availability and/or allocation of AAC may be a proximate mechanism underlying the incidence of polyandry in this and other species of moths.

Factors contributing to the poor performance of a soybean aphid parasitoid Binodoxys communis (Hymenoptera: Braconidae) on an herbivore resistant soybean cultivar

Host plant resistance and biological control are important components of integrated pest management programs. However, plants expressing resistance to herbivores may also have direct or indirect negative effects on natural enemies simultaneously providing pest suppression. Soybean aphids (Aphis glycines Matsumura) are invasive and serious pests of soybean (Glycine max L.) in the United States. Several soybean lines with aphid resistance have been identified, but the long-term impact of these resistant plants on soybean aphid biological control agents is uncertain. In a previous study, we reported that a soybean aphid parasitoid, Binodoxys communis (Gahan) had lower mummy production on resistant plants compared with a near isogenic susceptible soybean line, but the reason for this was unclear. Therefore, we examined three possible mechanisms to explain these findings: 1) resistant plants directly impact wasp emergence and longevity, 2) varying aphid density influences parasitism rates, and 3) resistant plants indirectly affect wasp development through reduced aphid longevity. We found that parasitoids in this study were not directly influenced by resistant cultivars, as there was no difference in wasp adult emergence or longevity between resistant and susceptible plants. There was also no significant effect of aphid density on mummy production over the range of aphid densities we tested. However, aphids on resistant plants had significantly shorter lifespans and were unable to survive long enough to develop into mummies compared with aphids on susceptible plants. We discuss these results and possible implications for integrating biological control and host plant resistance within soybean aphid integrated pest management programs.

Palmaria palmata (Dulse) as an unusual maritime aetiology of hyperkalemia in a patient with chronic renal failure: a case report

Introduction

Hyperkalemia is rare in individuals with normal renal function, regardless of dietary intake. This is due to the ability of the kidneys to adapt to increasing serum potassium concentrations. In patients with renal compromise, potassium homeostasis can become impaired. Palmaria palmata (dulse) is an edible seaweed known to be very rich in potassium. We report a case of hyperkalemia precipitated by the consumption of dulse by a patient with known renal disease.

Case Presentation

A 66-year-old Caucasian woman with diabetes and chronic renal disease presented to our emergency department with nausea, vomiting, and worsening malaise, which had been present for less than a day. She had undergone electrocardiogram monitoring, which showed bradycardia, and periods of asystole. Our patient denied any other symptoms. Laboratory analysis revealed a serum potassium level of 8.6 mmol/L (normal range 3.5 to 4.9 mmol/L). Although our patient was taking some medications known to influence renal function, the only recent change that she could recount was that she had consumed approximately 200 g of dulse within the preceding 24 hours. A diagnosis of hyperkalemia was made, and the patient was treated successfully, and discharged home in her pre-morbid state.

Conclusion

To the best of our knowledge, this is the first published report of hyperkalemia due to dulse consumption. Dulse is high in potassium, with concentrations upwards of 34 times greater than that found in bananas. Caution should be taken in prescribing medications with potential adverse renal effects for patients with known renal impairment. In such instances, renal function should be monitored closely. Patients should be counseled to avoid dietary sources high in potassium, with particular attention paid to unusual geographical dietary variations.

In-situ synthesis and performance of titanium oxide/poly(methyl methacrylate) nanocomposites

Polymer nanocomposites have elicited extensive research efforts due to their potential to exhibit spectacular properties. They have immense potential and are befitting materials to serve as an ideal and futuristic alternative for varied applications. Poly(methyl methacrylate) (PMMA) and titanium oxide (TiO2) nanocomposites used in this study were fabricated by an in-situ free radical polymerization process. Three point bend tests were conducted with a modified universal microtribometer to evaluate fracture toughness. The results indicated that the stress intensity values increase as the concentration of titanium oxide increases up to 1 vol% and subsequently decrease at higher concentrations. Scanning electron microscopy (SEM) images of fracture surfaces afforded clues as to the possible deformation mechanism. Ultraviolet-visible spectroscopy (UV-vis) evaluated the degree of transparency of the nanocomposites. It was observed that samples became opaque as the concentration was increased beyond 0.01% volume fraction. X-ray diffraction characterized the TiO2 crystalline phase and Scherrer's equation was used to calculate the crystallite size. Among the concentrations considered the 3% volume fraction sample had the largest crystallite size. Finally, microhardness measurements further characterized the mechanical properties of the composites.

Enzyme-catalyzed ring-opening copolymerization of 5-methyl-5-benzyloxycarbonyl-1,3-dioxan-2-one (MBC) with trimethylene carbonate (TMC): synthesis and characterization

Enzymatic ring-opening copolymerization of 5-methyl-5-benzyloxycarbonyl-1,3-dioxan-2-one (MBC) with trimethylene carbonate (TMC) was investigated. A route to aliphatic polycarbonates decorated with pendent carboxylic acid groups is demonstrated. Lipase from Pseudomonas fluorescens (AK) was selected to perform the copolymerization at various monomers feed ratios. Copolymers with different composition were prepared by varying the monomer feed ratio from 10% to 80% MBC. 1H, 13C, and 1H-13C HETCOR NMR spectra were used to analyze the microstructure of the copolymers. The 1H NMR spectra indicated lower incorporation of TMC in the copolymer than was expected from the monomer feed ratio. Analysis of the 13C spectra did not indicate an ordered structure but instead suggested the formation of random polymers. This was further confirmed by the thermal data obtained for representative samples. The thermal properties at different feed ratios of poly[MBC-co-TMC] copolymers were investigated by differential scanning calorimetry (DSC). No melting temperature (Tm) for either homopolymers or copolymers was observed. A plot of 1/Tg(K) vs the weight composition of MBC in the copolymers was constructed and was consistent with copolymers that tend toward random distribution; this was confirmed from the NMR data.

Vascular embolization of benign granulosa cells

OBJECTIVE(S)

Most conditions involving sex cord-stromal cells can be diagnosed on morphologic criteria alone. We describe a case of vascular embolization of benign granulosa cells in which immunohistochemistry was of value as a diagnostic tool.

METHODS

We reviewed the clinical history and gross pathologic findings from a 48-year-old patient who presented with abdominal pain and fullness. Formalin-fixed paraffin-embedded sections were examined by routine H&E and immunohistochemical stains.

RESULTS

Histologic examination of a grossly enlarged and cystic ovary revealed nests of cells within angiolymphatic spaces. Although the cells were cohesive and atypical, they were morphologically similar to the nearby graafian follicle. Immunohistochemistry showed positive labeling with antibodies to inhibin-alpha and cytokeratin in a pattern consistent with benign granulosa cells.

CONCLUSION(S)

Immunohistochemical stains for inhibin-alpha and cytokeratin are useful tools to help confirm granulosa cell origin, as demonstrated in this case involving an atypical histomorphologic picture of "embolization."

Cancer-associated retinopathy in a patient with advanced epithelial ovarian carcinoma

BACKGROUND

Paraneoplastic phenomena, such as retinopathy, may herald an unsuspected gynecologic malignancy.

CASE

A 75-year-old woman presented to a neuro-ophthalmologist with abrupt onset of unilateral visual loss. A diagnosis of branch retinal artery occlusion was made and she was treated with aspirin. An echocardiogram subsequently revealed atrial dilation and she was placed on coumadin therapy. Her vision worsened and a cancer-associated retinopathy was entertained. A serum cancer-associated retinopathy antibody was detected; subsequent computed tomographies of the abdomen and pelvis revealed findings consistent with a primary ovarian carcinoma.

CONCLUSION

Patients with unexplained ophthalmologic symptoms may harbor an underlying gynecologic cancer.

Prenatal ultrasound detection of isolated neural tube defects: is cytogenetic evaluation warranted?

OBJECTIVE

To determine the value of cytogenetic evaluation in fetuses with isolated neural tube defects diagnosed by prenatal ultrasound.

METHODS

Fifty-five thousand two hundred sixty obstetric ultrasounds performed for various indications at the Indiana University Prenatal Diagnostic Center from July 1988 to March 1994 were reviewed using a computerized data base. Excluding all cases of anencephaly, fetuses with isolated neural tube defects were identified. Maternal demographic data, pregnancy outcomes, level of defect, and fetal karyotype when available were obtained. Statistical analysis was performed using the chi 2 test, when appropriate. P < or = .05 was considered statistically significant.

RESULTS

Seventy-seven medical record charts of women with prenatally diagnosed isolated fetal neural tube defects were reviewed. Nineteen pregnancies were terminated, 42 pregnancies were delivered, and 16 pregnancies were lost to follow-up. Karyotypes were available in 43 of the 77 cases (55.8%). The theoretical risk of chromosomal anomalies in this sample population based solely on maternal age was 0.3%. Of the 43 documented karyotypes, seven chromosomal anomalies were discovered (16.3%). The difference was statistically significant (P = .012). Detected chromosomal anomalies included two trisomy 18, two triploid 69,XXX, one triploid 69,XXY, one balanced Robertsonian translocation t(13q,14q), and one inversion in the q arm of the X chromosome.

CONCLUSION

The prevalence of karyotypic abnormalities is significantly increased in fetuses with isolated neural tube defects; therefore, prompt antenatal genetic evaluation should be considered in such cases.

Neural tube defects and omphalocele in trisomy 18

A trisomy 18 fetus with severe congenital anomalies including craniorachischisis, large omphalocele, and bilateral cleft lip and palate is reported. The occurrence of neural tube defects and/or omphalocele in reported cases of trisomy 18 is discussed and the frequency of these anomalies in 85 trisomy 18 patients evaluated at Indiana University School of Medicine from 1963 to 1986 is reviewed. In this series of patients the frequency of neural tube defects was 7.0% and the frequency of omphaloceles was 5.9%. The percentage of these findings in our cases supports the premise that neural tube defects and omphaloceles are part of the trisomy 18 phenotype. Since fetuses with trisomy 18 are subject to early fetal loss or premature birth, the more subtle physical features of this condition may not be apparent. Thus, karyotyping of fetuses and premature infants with either neural tube defect or omphalocele should be considered.

Acephalus-acardia in twins with aneuploidy

Since 1963, 11 cases have been reported in which both the acardiac twin and the "normal" co-twin were studied cytogenetically. Aneuploidy or polyploidy was clearly identified in the acardiac twin in 7 cases and in the co-twin in 1 case. We report on 2 additional twin pairs in which aneuploidy was associated with acephalus-acardia. In both cases the "normal" co-twin had a Klinefelter (47,XXY) karyotype. Chromosome analysis in the 2 acardiac twins documented a 47,XXY constitution in one and 94,XXXXYY anomaly in the other. One of the "normal" co-twins also had the VATER association. Given these data we would recommend chromosome analysis of both members of a twin pair when one has acephalus-acardia.