Processing of silicon solar cells by ion implantation and laser annealing

Methods to improve the radiation tolerance of silicon cells for spacecraft use are described. The major emphasis of the program was to reduce the process-induced carbon and oxygen impurities in the junction and base regions of the solar cell, and to measure the effect of reduced impurity levels on the radiation tolerance of cells. Substrates of 0.1, 1.0 and 10.0 ohm-cm float-zone material were used as starting material in the process sequence. High-dose, low-energy ion implantation was used to form the junction in n+p structures. Implant annealing was performed by conventional furnace techniques and by pulsed laser and pulsed electron beam annealing. Cells were tested for radiation tolerance at Spire and NASA-LeRC. After irradiation by 1 MeV electrons to a fluence of 10 to the 16th power per sq cm, the cells tested at Spire showed no significant process induced variations in radiation tolerance. However, for cells tested at Lewis to a fluence of 10 to the 15th power per sq cm, ion-implanted cells annealed in vacuum by pulsed electron beam consistently showed the best radiation tolerance for all cell resistivities

Peripheral blood and ovarian levels of sex steroids in the cyclic hamster

Changes in progesterone (P), testosterone (T), estrone (E1) and estradiol-17β (E2) in peripheral blood, ovary, corpora lutea (CL) and in the nonluteal portion of the ovary (NLO) were studied in the cyclic hamster by RIA. In addition, androstenedione (A) was measured, but only in serum. Serum P levels were the same on Days 1 (day of ovulation) and 2 at 0900 h (5 ng/ml), but declined markedly on Day 3 and on the morning of Day 4 (proestrus). After the LH surge on the afternoon of Day 4, serum and ovarian levels of P increased abruptly until 1900 h to 11-18 ng/ml and declined slowly thereafter. Peak T levels in both serum (209 pg/ml) and the ovary occurred between 1400-1500 h of Day 4, paralleling the rising P levels. However, T levels declined rapidly after 1600 h to undetectable levels by 1900 h, but there was a second peak of T by 2300 h in serum which was matched by the ovary. Serum levels of E1 and E2 began to rise on Day 2, reaching peak values by Day 4 between 1200 and 1400 h (41 pg/ml and 152 pg/ml, respectively). Peak ovarian concentrations of E1 and E2 were reached on Day 4 at 0900 h. These high levels were maintained up to 1600 h of Day 4 and declined rapidly thereafter. The serum levels of E1 were about one-third as high as E2 and were not as drastically affected on the evening of Day 4. Serum androstenedione ranged from 1-2 ng/ml, but changes throughout the cycle were not as striking as for the other steroids. However, increased levels of A were associated with decreased levels of estrogens and vice-versa. Therefore, the circulating levels of A probably reflect altered secretion rates of other steroids. Administration of 5 μ g LH on the evening of Day 4 (when all steroid levels are declining) caused significant increases in P and T but not E2. Hence, the refractory period of estrogen synthesis on the evening of Day 4 cannot be attributed to insufficient levels of LH during the preovulatory period

Ovarian steroidogenesis in the proestrous hamster

In the proestrous hamster, in response to the LH surge, there is a dramatic and sustained increase in serum progesterone (P) and transitory increases in testosterone (T), estrone (E1) and estradiol-17β (E2). Ovarian steroidogenesis in the proestrous hamster was analyzed in detail by studying: 1) concentrations of these steroids in the whole ovary, antral follicles (AF) and the nonantral follicular portion of the ovary (NAO) at 1200 h (prior to the LH surge), 1500 h (during the LH surge) and 1800 h (after the LH surge); 2) in vitro steroidogenic production by the AF and NAO, as well as the whole ovary (removed before 1200 h, 1500 h and 1800 h and 3) in vitro effects of LH, FSH and P on steroidogenesis of ovaries removed before the LH surge and incubated for 2 h. P concentration was the same in AF and NAO at 1200 h but increased slightly in the AF with the onset of the LH surge. Both the concentration and production rate of P increased from a minimum at 1200 h (1 ng/mg/h) to a maximum by 1800 h (30 ng/mg/h) in the ovary, AF and NAO. On the other hand, the concentration of T, E1 and E2 was selectively greater in the AF at all times. Maximum T production occurred in the ovaries removed during the LH surge (150 pg/mg/h) followed by a significant decline by 1800 h. However, AF produced negligible amounts of T at all times. In the NAO, the production of T was essentially the same (about 20 pg/mg/h) in all 3 incubations. The production of E1 and E2 was much greater in the AF than in the NAO, especially between 1200-1500 h. By 1800 h, the levels and synthetic capacity for estrogens in the ovary, AF and NAO declined to baseline levels, while the production of P was still very high. These studies indicate that in the proestrous hamster, steroidogenesis in the NAO which largely represents the interstitial compartment is limited to the production of P and androgens and only a negligible fraction passes down the pathway to form estrogens. On the other hand, steroidogenesis is more complete in the AF where it can proceed efficiently as far as estrogens. LH (5-250 ng/ml) added in vitro increased the production rate of all steroids whereas 1 ng LH increased only the synthesis of E2. FSH (100-200 ng/ml) also stimulated E2 production but not E1. Higher concentration of FSH (250 ng/ml) resulted in overall increases in P, T, E1 and E2 possibly due to contamination with LH. Exogenous P (10, 100 ng/ml) had no effect on T or E1 synthesis, but E2 production was enhanced

Interstitium: site of steroid synthesis in the ovary of the long term hypophysectomized hamster

The ovaries of hamsters hypophysectomized (H̅) on the afternoon of proestrus synthesize in vitro substantial amounts of progesterone for as long as 20 days post-H̅ (Taya and Greenwald, 1979b). The purpose of the present study was to identify by histochemistry and ultrastructure the ovarian cell type which still possessed the enzymes capable of steroidogenesis despite the long term absence of gonadotropins. After Day 6 post-H̅, the ovaries contained interstitium and viable and atretic small preantral follicles. The viable preantral follicles were histochemically devoid of Δ 5-3β -hydroxysteroid dehydrogenase (3β -HSDH). Histochemically, there were no appreciable changes in lipids in the interstitial gland cells (IGC) until Day 20 post-H̅, followed by a slight decrease by Day 30. The 3β -HSDH activity in the IGC showed no appreciable changes until Day 6 and thereafter decreased gradually until Day 30. Trace amounts of glucose-6-phosphate dehydrogenase were found in the IGC until Day 6 and thereafter the enzyme was undetectable. The IGC contained only trace amounts of acid phosphatase until Day 10, followed by a gradual increase by Day 30. A single i.p. injection of 5 μg ovine LH on Day 10, 20 or 30 resulted 3 h later in dramatic increases in the concentration of serum progesterone and ovarian progesterone and testosterone but not estradiol-17β . Concomitantly, the depletion of lipid droplets in viable interstitial cells was observed by histochemical and ultrastructural criteria. However, lipid accumulations in degenerating interstitial cells and atretic granulosa cells were unaffected by LH treatment. These data indicate that the interstitium is an active steroidogenic tissue for at least 30 days post-H̅ and that LH can rapidly stimulate synthesis and secretion of progesterone and testosterone by the interstitium in long term hypophysectomized hamsters

At the intersection of sleep deficiency and opioid use: mechanisms and therapeutic opportunities

Due to the ongoing opioid epidemic, innovative scientific perspectives and approaches are urgently needed to reduce the unprecedented personal and societal burdens of nonmedical and recreational opioid use. One promising opportunity is to focus on the relationship between sleep deficiency and opioid use. In this review, we examine empirical evidence: (1) at the interface of sleep deficiency and opioid use, including hypothesized bidirectional associations between sleep efficiency and opioid abstinence; (2) as to whether normalization of sleep deficiency might directly or indirectly improve opioid abstinence (and vice versa); and (3) regarding mechanisms that could link improvements in sleep to opioid abstinence. Based on available data, we identify candidate sleep-restorative therapeutic approaches that should be examined in rigorous clinical trials

In-Vitro steroidogenesis of newly formed corpora lutea and the non-luteal ovary in the rat, rabbit, hamster and guinea-pig

The steroidogenic abilities of the newly formed corpus luteum (8-10 h after ovulation) and the non-luteal ovary were compared in the guinea-pig, hamster, rabbit and rat using an invitro incubation technique. Histologically, newly formed rat corpora lutea (CL) were highly luteinized whereas the CL of the rabbit and guinea-pig were only partially luteinized. The CL of the hamster showed the least amount of luteinization. Serum progesterone was highest in the rat (18 ± 3 (s.e.m.) ng/ml). In the hamster, it was about 8 ng/ml, whereas in the rabbit and guinea-pig it was about 1 ng/ml. Serum androstenedione ranged between 0.5 and 1 ng/ml. Serum testosterone was lowest in the hamster (60 pg/ml) and highest in the rabbit (470 pg/ml), whereas in the rat and guinea-pig, testosterone levels were similar (about 240 pg/ml). Serum oestrogens were at baseline levels in all species. The CL of the rat exhibited considerably greater steroidogenic ability than the CL of the other species, producing 70 ± 6 ng progesterone/mg per h, 215 ± 14 pg androstenedione/mg per h, 49 ± 3 pg testosterone/mg per h, 3 pg oestrone/mg per h and 1 pg oestradiol/mg per h. Rabbit CL produced only progesterone (7 ± 2 ng/mg per h). Newly formed hamster CL produced none of the above steroids. In general, the ability of the CL to produce progesterone in vitro correlated with the degree of luteinization found by histological observation. Guinea-pig CL were embedded deeply in the ovary and could not be obtained without damage. Consequently, a portion of the ovary containing a corpus luteum was incubated. There was no difference in the steroid production by this portion of the ovary compared with the non-luteal ovary. The non-luteal ovary of the rat produced the highest amount of progesterone (10 ± 2 ng/mg per h). The guinea-pig non-luteal ovary produced about 5 ± 2 ng progesterone/mg per h, whereas the non-luteal ovary of the rabbit did not produce any. On the other hand, the hamster non-luteal ovary lost progesterone. Non-luteal ovaries from all species produced androgens. The non-luteal ovary of the guinea-pig contained especially large numbers of atretic antral follicles. The guinea-pig non-luteal ovary produced extremely large amounts of androstenedione (1110 ± 210 pg/mg per h) and testosterone (606 ± 154 pg/mg per h) compared with the amounts produced by the non-luteal ovary of the rat, hamster and rabbit. In the non-luteal ovary, interstitium and atretic antral follicles are the probable source of androgens. Oestrogen production by the non-luteal ovary was at baseline levels in the four species studied correlating with the absence of healthy antral follicles. The results indicate the extreme species differences that exist in ovarian function in the early postovulatory period

Macroeconomic Fluctuations, Inequality, and Human Development

This paper examines the two-way relationship between inequality and economic fluctuations, and the implications for human development. For years, the dominant paradigm in macroeconomics, which assumed that income distribution did not matter, at least for macroeconomic behavior, ignored inequality--both its role in causing crises and the effect of fluctuations in general, and crises in particular, on inequality. But the most recent financial crisis has shown the errors in this thinking, and these views are finally beginning to be questioned. Economists who had looked at the average equity of a homeowner--ignoring the distribution--felt comfortable that the economy could easily withstand a large fall in housing prices. When such a fall occurred, however, it had disastrous effects, because a large fraction of homeowners owed more on their homes than the value of the home, leading to waves of foreclosure and economic stress. Policy-makers and economists alike have begun to take note: inequality can contribute to volatility and the creation of crises, and volatility can contribute to inequality. Here, we explore the variety of channels through which inequality affects fluctuations and fluctuations affect inequality, and explore how some of the changes in our economy may have contributed to increased inequality and volatility both directly and indirectly. After describing the two-way relationship, the paper discusses hysteresis--the fact that the consequences of an economic downturn can be long-lived. Then, it examines how policy can either mitigate or exacerbate the inequality consequences of economic downturns, and shows how well-intentioned policies can sometimes be counterproductive. Finally, it links these issues to human development, especially in developing countries

BDNF Val 66 Met genotype is associated with drug‐seeking phenotypes in heroin‐dependent individuals: a pilot study

Brain‐derived neurotrophic factor (BDNF) Val 66 Met genotype has been associated with neurobehavioral deficits. To examine its relevance for addiction, we examined BDNF genotype differences in drug‐seeking behavior. Heroin‐dependent volunteers ( n  = 128) completed an interview that assessed past‐month naturalistic drug‐seeking/use behaviors. In African Americans ( n  = 74), the Met allele was uncommon (carrier frequency 6.8%); thus, analyses focused on European Americans ( n  = 54), in whom the Met allele was common (carrier frequency 37.0%). In their natural setting, Met carriers ( n  = 20) reported more time‐ and cost‐intensive heroin‐seeking and more cigarette use than Val homozygotes ( n  = 34). BDNF Val 66 Met genotype predicted 18.4% of variance in ‘weekly heroin investment’ (purchasing time × amount × frequency). These data suggest that the BDNF Met allele may confer a ‘preferred drug‐invested’ phenotype, resistant to moderating effects of higher drug prices and non‐drug reinforcement. These preliminary hypothesis‐generating findings require replication, but are consistent with pre‐clinical data that demonstrate neurotrophic influence in drug reinforcement. Whether this genotype is relevant to other abused substances besides opioids or nicotine, or treatment response, remains to be determined.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/99593/1/adb431.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/99593/2/adb431_sm_fig_s1.pd